
^{12}C (1975AJ02)(See Energy Level Diagrams for ^{12}C) GENERAL: See also (1968AJ02) and Table 12.8 [Table of Energy Levels] (in PDF or PS). Shell model: (1967SV1A, 1968BA1L, 1968DR1B, 1968FA1B, 1968FU1B, 1968GO01, 1968GU1C, 1968HA11, 1968RO1G, 1969GU1E, 1969GU03, 1969IK1A, 1969LA26, 1969MO1F, 1969SA1A, 1969SV1A, 1969WA06, 1969WO05, 1970AR21, 1970BE26, 1970BO33, 1970BO1J, 1970CO1H, 1970DE1F, 1970DO1A, 1970EI06, 1970GI11, 1970GU11, 1970KH01, 1970KO04, 1970KR1D, 1970LO1C, 1970RE1G, 1970RU1A, 1970RY1A, 1970SV1B, 1970WO12, 1971AR1R, 1971BO29, 1971GR16, 1971GU11, 1971NO02, 1971RO03, 1971ZO03, 1971ZO01, 1972AB12, 1972BE1X, 1972BO38, 1972BR1G, 1972FO1G, 1972JA18, 1972KR1D, 1972LE1L, 1972MS01, 1972RE03, 1972SA1B, 1972SU01, 1972VE01, 1973BO07, 1973EL04, 1973FR09, 1973HA05, 1973HA49, 1973KU03, 1973LO1C, 1973SA30, 1973YA1A, 1974HU1D, 1974KA11, 1974KU05). Collective and deformed models: (1968HE1C, 1969AB05, 1969BA1R, 1969RU04, 1970DA13, 1970KH01, 1970SH1C, 1970SV1B, 1970TU01, 1970WE1B, 1971AR1R, 1971BO29, 1971CI03, 1971HO19, 1971SP11, 1971ZO03, 1971ZO01, 1972AB1C, 1972BE1X, 1972BO38, 1972FO1G, 1972HO56, 1972LE1L, 1973BO07, 1973CA16, 1973DO10, 1973FU1E, 1973KO1F, 1973LA35, 1973MS01, 1973YA1A, 1974AR04, 1974LE04, 1974TA19). Cluster and alpha particle model: (1968FU1A, 1968HE1B, 1968PI1A, 1968TA1G, 1969AB1B, 1969BA1J, 1969BE1K, 1969BR1H, 1969HE1G, 1969HU1C, 1969IK1A, 1969KI02, 1969KO1K, 1969LE21, 1969NA1C, 1969SM1A, 1969TA1F, 1969TA1C, 1969WA06, 1969YA1A, 1970BA1Q, 1970BR35, 1970DE45, 1970EI05, 1970EI06, 1970EL01, 1970HU1F, 1970KO26, 1970LI24, 1970MC1D, 1970NE1F, 1970NO1A, 1970YU02, 1970ZI04, 1971AB07, 1971AB1B, 1971BA85, 1971BO20, 1971DA13, 1971DU06, 1971FR06, 1971FR15, 1971KH06, 1971KU1G, 1971NO03, 1971NO02, 1971OS04, 1971RA36, 1971RI1D, 1971SA1A, 1971TA13, 1971VI05, 1972AB1C, 1972AB11, 1972AB19, 1972AK10, 1972AN12, 1972AN15, 1972BA59, 1972DE03, 1972FR1B, 1972GR42, 1972HO56, 1972IK1A, 1972LE40, 1972RU13, 1972TU01, 1972VA40, 1972ZI03, 1972ZI05, 1973AB1G, 1973AB1A, 1973AN05, 1973BE1L, 1973CO13, 1973CO15, 1973FU1E, 1973HA57, 1973IK1A, 1973KH1A, 1973KU03, 1973LA35, 1973SA38, 1973YA1A, 1974AB05, 1974HO1Q, 1974JA24, 1974KA23, 1974KA11, 1974ME08, 1974SM1A, 1974SM04, 1974SU1B, 1974VA1N). Special levels: (1966BR1D, 1967MA1B, 1968CE01, 1968LA1B, 1969GU03, 1969HA1G, 1969HA1F, 1969SO1E, 1969WO05, 1970AR21, 1970BO33, 1970BO1J, 1970DA13, 1970GO41, 1970GR27, 1970PE18, 1970RO20, 1970RU1A, 1971AR1R, 1971BE2B, 1971FA11, 1971FR15, 1971GR1V, 1971GR23, 1971GR38, 1971GR49, 1971MC15, 1971NO02, 1971RO03, 1971SE03, 1971VI05, 1971WA27, 1972AI01, 1972BE1X, 1972DE03, 1972EN05, 1972HA1R, 1972JA18, 1972SU01, 1972SU04, 1972VA40, 1973BO07, 1973CA1J, 1973IK1A, 1973KH1A, 1973KN1C, 1973MA1K, 1973MI1F, 1973SA30, 1973YA1A, 1974AR04, 1974HA1G, 1974IT1A, 1974KA11, 1975SH01). Giant resonance: (1968BA1J, 1969DR05, 1969MA22, 1969RO26, 1969UB01, 1970FI1D, 1970FR1E, 1970GU12, 1971DU13, 1971GR23, 1971GU10, 1971SE03, 1971WA27, 1972KA33, 1972KE06, 1972MS01, 1972SU01, 1972NA05, 1973BA05, 1973DE53, 1973HA1Q, 1973MA1T, 1973MS01, 1973MS02, 1973PI06, 1973SU03, 1974CA1R, 1974FA1A, 1974MU13). Special reactions: (1968BR1E, 1969GA18, 1971AR02, 1971BA16, 1972AB11, 1973AZ1A, 1973BU12, 1973DE07, 1973KU03, 1973WI15, 1974FO22, 1974RE1B, 1975CR01, 1975KU01). Electromagnetic transitions: (1968CA08, 1968LA1B, 1969AB05, 1969DR05, 1969HA1G, 1969HA1F, 1969LA26, 1970DO1A, 1970WE1B, 1971TA13, 1972AB12, 1972BE1X, 1972BE98, 1972BO38, 1972DE03, 1972NA05, 1973AL14, 1973BE1L, 1973BO07, 1973BO31, 1973CA16, 1973EL04, 1973HA49, 1973HA1Q, 1973KU1N, 1973LE1E, 1973SA30, 1974AB05, 1974FI03, 1974MU13). Astrophysical questions: (1967SH1B, 1967WI1B, 1968DU1C, 1969TR1A, 1970OH1B, 1972CL1A, 1972KO1A, 1972UL1A, 1973AR1H, 1973AU1B, 1973AU1D, 1973AU1C, 1973BO1R, 1973CA1B, 1973CO1J, 1973CO1B, 1973DA1L, 1973GR1G, 1973IB1B, 1973RA1D, 1973SA1J, 1973SC1T, 1973SM1A, 1973TA1E, 1973TA1D, 1973TR1C, 1973TR1B, 1973UL1B, 1974AR1G, 1974BE1R, 1974BO2K, 1974DA1N, 1974LA1J, 1974LA1K, 1974PA1E, 1974SC1F, 1974SN1B, 1974TO1C, 1974WI1F, 1975FA1H, 1975TA1E). Muon and neutrino capture and reactions: (1967EV1B, 1967HI1B, 1968FR1E, 1968FU1B, 1968HI1C, 1968KE1D, 1968RH1A, 1969DI1C, 1969OZ1A, 1969VA37, 1969WU1A, 1970BU1B, 1970CA1H, 1970CA1J, 1970FR1E, 1970HI09, 1970PR1H, 1971AG01, 1971BA96, 1971LA1J, 1971MO1Q, 1971MU20, 1971PI1D, 1971PL01, 1971PL1F, 1972CA08, 1972DE50, 1972KE06, 1972LO1J, 1972MI15, 1972OC01, 1972UB01, 1973BA68, 1973BE51, 1973BE38, 1973CH16, 1973DO04, 1973KI12, 1973KU1N, 1973MU04, 1973MU11, 1973SA1U, 1974DE1V, 1974DO1C, 1974DU02, 1974IM1C, 1974KA1Q, 1974KO1M, 1974PO05, 1974VO12, 1975SU1G). Pion capture and pion reactions: (1965CH12, 1965GI10, 1967FO1A, 1967KO1B, 1967LE1D, 1967MI1B, 1968AG1A, 1968AG1C, 1968BA1M, 1968BA48, 1968BA61, 1968BE1F, 1968BI1B, 1968CH1D, 1968DA1G, 1968ER1A, 1968GO1L, 1968KE1D, 1968KO1B, 1968KO1C, 1968NO1A, 1968RH1A, 1968ST1G, 1968TA1C, 1968UB1A, 1968VA1F, 1968WI1B, 1968WI1D, 1968ZE1A, 1968ZU1A, 1969AG1A, 1969BA1L, 1969CA1B, 1969CH1C, 1969CH19, 1969GO1C, 1969HE1E, 1969KO1F, 1969MA1C, 1969MO1E, 1969MO1G, 1969UB01, 1969WE05, 1970AB1A, 1970BA44, 1970BA1E, 1970BA1F, 1970BE1J, 1970BE1L, 1970BI1A, 1970BI10, 1970BJ1A, 1970CA1J, 1970CH1F, 1970CH1C, 1970EL1E, 1970ER1A, 1970GO28, 1970GO1F, 1970HI09, 1970HI10, 1970HI11, 1970JA23, 1970JO18, 1970KA1H, 1970KA1J, 1970KO23, 1970KO26, 1970KR1F, 1970MA18, 1970SC1P, 1970RA39, 1970ST21, 1970VA18, 1970WI21, 1971AM1A, 1971BI1K, 1971CA01, 1971CA1J, 1971DE31, 1971ED02, 1971FA09, 1971GO22, 1971GO29, 1971GR1X, 1971GR34, 1971GU11, 1971GU1H, 1971GU13, 1971IN1A, 1971KO30, 1971KO40, 1971LA1P, 1971LE14, 1971LE1Q, 1971LO1H, 1971MA1C, 1971MA29, 1971MA1P, 1971MA1T, 1971MA2A, 1971MO29, 1971PE1D, 1971RO14, 1971RO1L, 1971SE02, 1971SI36, 1971SK03, 1971SK02, 1971ST10, 1971TH05, 1972AB1H, 1972AL45, 1972BA13, 1972BE34, 1972BE36, 1972BI09, 1972BU1P, 1972DE07, 1972ER02, 1972ER1A, 1972FA03, 1972FA14, 1972FU1C, 1972FU22, 1972GI04, 1972HU1A, 1972HU1F, 1972JA1H, 1972KO31, 1972LA01, 1972LA10, 1972LA24, 1972LE03, 1972LE40, 1972MA1H, 1972MA32, 1972NI13, 1972SA10, 1972SC18, 1972SC40, 1972SE13, 1972SE1F, 1972SI24, 1972ST1H, 1972SW1A, 1972VA1K, 1972YO1C, 1973AL09, 1973AL1E, 1973AL14, 1973AL1A, 1973AN18, 1973AR1B, 1973AS1A, 1973BA2G, 1973BA1E, 1973BE2C, 1973BE2B, 1973BE2D, 1973BE47, 1973BR1J, 1973BU1B, 1973BU12, 1973CA1J, 1973CA17, 1973CA1L, 1973CL1J, 1973DA1G, 1973DE1Y, 1973DI08, 1973DO1F, 1973DU1C [η], 1973EI01, 1973FA1N, 1973GA20, 1973GE11, 1973GO18, 1973GO44, 1973GO41, 1973GR1J, 1973GR1F, 1973HA34, 1973HE30, 1973HO43, 1973HS1A, 1973HS1B, 1973HU1E, 1973JA1K, 1973KA1D, 1973KI03, 1973LA1N, 1973LA30, 1973LE1F, 1973LE22, 1973LI18, 1973LU1A, 1973MA10, 1973MA11, 1973MO1H, 1973MO20, 1973MO26, 1973NY04, 1973PE1E, 1973RO10, 1973RO1Q, 1973SE1E, 1973SH1E, 1973SI1N, 1973ST1K, 1973UB01, 1973WA1J, 1973WI1A, 1973YE02, 1973ZI1A, 1974AM01, 1974AZ02, 1974BA2E, 1974BO27, 1974BU1H, 1974CA21, 1974CA1P, 1974CA1G, 1974CA1Q, 1974CA25, 1974CL04, 1974CU1A, 1974DE1U, 1974EP02, 1974GA08, 1974GI08, 1974HA61, 1974HE1F, 1974HO29, 1974HU14, 1974KI01, 1974KO14, 1974KO07, 1974KU1K, 1974KU02, 1974LA12, 1974LA22, 1974LE1L, 1974LE1M, 1974LI1H, 1974LI08, 1974LI15, 1974MA37, 1974MI07, 1974MI06, 1974MI11, 1974MI12, 1974MU03, 1974NE18, 1974NI08, 1974OH01, 1974PI02, 1974ST1G, 1974TA18, 1974UL02, 1974VO12, 1974WI1P, 1975AR02, 1975GE02, 1975HE1M, 1975PI1E, 1975YA02). Kaon capture and kaon reactions: (1968CH1F, 1969KU1B, 1971MA1T, 1972BA09, 1972BL10, 1972JU1A, 1972WA1F, 1973BA1Y, 1973BO1W, 1973BO1X, 1973BU1H, 1973CH1M, 1973FA1P, 1973GO41, 1974AL1J, 1974CA1H, 1974DE41, 1974HU1D, 1974HU1E, 1974MO1H, 1975KI1M). Other topics: (1966BR1D, 1967KU1D, 1968BA1L, 1968BA1J, 1968BO1H, 1968FA1B, 1968GU1C, 1968IR1A, 1968LA1B, 1968LE1F, 1968NE1C, 1968RO1G, 1968TK1A, 1969AB05, 1969CH1A, 1969DR05, 1969GU03, 1969GR1A, 1969HO1M, 1969IR1A, 1969KE1B, 1969LA26, 1969LE21, 1969LO06, 1969MC1C, 1969NA1E, 1969RU04, 1969SH1A, 1969SO08, 1969SO1E, 1969VI1C, 1969VO1E, 1970BE26, 1970BO1M, 1970BO1J, 1970DR07, 1970EF01, 1970GR44, 1970HO1J, 1970JA02, 1970KA30, 1970KA1K, 1970PE18, 1970RE1G, 1970RU1A, 1970RY03, 1970SU1B, 1970VA07, 1971BA85, 1971BE2B, 1971BO1F, 1971FA11, 1971GR1V, 1971GR2C, 1971GR35, 1971GR49, 1971HO19, 1971KA14, 1971KU1G, 1971MC15, 1971NG01, 1971OS04, 1971SO11, 1971ST40, 1971TU04, 1971VO1E, 1971ZO03, 1972AB12, 1972AI01, 1972AN05, 1972AR13, 1972BR1G, 1972EL1E, 1972FO1G, 1972FR1B, 1972FR09, 1972HA57, 1972KO01, 1972KR11, 1972KR1D, 1972LE1L, 1972OC01, 1972PA32, 1972PN1A, 1972RE03, 1972SA1B, 1972ST02, 1972SU04, 1972TU01, 1972VE01, 1972ZI03, 1973AN05, 1973AV1C, 1973BA1Y, 1973BO31, 1973CL09, 1973DE07, 1973DZ1A, 1973ED1A, 1973EL04, 1973ER1C, 1973ER10, 1973FA1P, 1973FO1F, 1973FR09, 1973GR36, 1973HA05, 1973HA57, 1973KO26, 1973KU03, 1973KU1G, 1973LA35, 1973LO1C, 1973MA48, 1973MI1F, 1973PE05, 1973PO1D, 1973RA1E, 1973RO1R, 1973SA1T, 1973SI21, 1973UL01, 1973VA01, 1974AB05, 1974AR04, 1974AU1E, 1974CA1H, 1974DU11, 1974DZ03, 1974FA1A, 1974FI03, 1974HO1J, 1974HU1D, 1974HU1E, 1974IR04, 1974ME08, 1974MU13, 1974SI1F, 1974ZA01, 1975GR03, 1975KI1M, 1975KU01, 1975SH01, 1975ZI1D). Ground state: (1968BA1L, 1968BO1H, 1968FA1B, 1969AB05, 1969AG03, 1969GU03, 1969KE1B, 1969LA26, 1969LE21, 1970EL01, 1970GR44, 1970ST19, 1971BO20, 1971BO29, 1971GR16, 1971GR2C, 1971RU14, 1971ZO03, 1972AB12, 1972AV1D, 1972BE1X, 1972BR1G, 1972DE03, 1972FR09, 1972GR1K, 1972GR42, 1972KR11, 1972KR1D, 1972LE1L, 1972SI24, 1972VA40, 1972VE01, 1973AB1A, 1973AR1C, 1973BU12, 1973CA16, 1973DO1F, 1973EN1E, 1973ER1C, 1973ER10, 1973FE13, 1973FO1F, 1973GR36, 1973HA57, 1973KO26, 1973KU1L, 1973LE1E, 1973LO1C, 1973PE05, 1973SA38, 1973SA30, 1973VA01, 1974AB05, 1974AD1C, 1974AR04, 1974BA1Z, 1974DU02, 1974DZ03, 1974JA24, 1974KA23, 1974MU13, 1974SI03, 1974VA1N, 1974ZA01).
For E(^{6}Li) = 1.2 to 2.8 MeV, population ratios of ^{7}Be*(0.43), ^{7}Li*(0.48) and ^{10}B*(0.72) (reactions (c), (e) and (f)) remain approximately constant. Simple tunneling or compound nucleus models are not compatible with the data and a direct interaction through longrange tails is suggested (1962MC12). Absolute reaction cross sections at E(^{6}Li) = 2.1 MeV are in reasonable agreement with estimates based on barrier penetration. A strong preference for αemission suggests that the favored mechanism involves interacting clusters (1963HU02). The α_{0} yield (0°) (reaction (d)) shows two broad peaks at E(^{6}Li) = 4 and 9 MeV (1967CA1D: prelim. results; E(^{6}Li) = 2 to 14.5 MeV) while (1970FR06: E(^{6}Li) = 4 to 24 MeV) report a broad peak at E(^{6}Li) ≈ 10 MeV. The yield of ^{6}Li + ^{6}Li → 3α (reaction (g)) for E(^{6}Li) = 4 to 20 MeV is dominated by a broad resonance (Γ = 5 MeV) at the Coulomb barrier, which is consistent with the formation of a quasimolecular state ^{6}Li + ^{6}Li with τ ≈ 10^{21} sec (1970FR06). A multiparameter coincidence study of reaction (g) for E(^{6}Li) = 2 to 13 MeV shows the importance of direct interactions: the data were fitted assuming an (α + d) cluster structure for ^{6}Li and an interaction potential acting only between the two deuterons (1971GA1N, 1971GA21, 1972GA32). See also (1971WY01), (1968AJ02) for the earlier work, ^{8}Be and ^{10}B in (1974AJ01) and ^{11}B and ^{11}C for reactions (a) and (b).
The elastic scattering (reaction (b)) follows the Mott formula at low energies [≲ 4.0 MeV] (1966PI02: E(^{6}Li) = 3.2 to 7.0 MeV). A broad structure is observed in the excitation functions [θ_{c.m.} = 60° and 90°] at E(^{6}Li) ≈ 13 MeV (1973GR34) and ≈ 26 MeV [Γ ≈ 7 MeV] (1971FO08: θ_{c.m.} = 90°; E(^{6}Li) to 34 MeV). The elastic scattering appears to be dominated by absorption (1971FO08). See also (1973GO01). Excitation functions for the transitions to ^{6}Li^{*}_{3.56} + ^{6}Li^{*}_{3.56} have been measured for E(^{6}Li) = 28.0 to 33.0 MeV (1970NA02: θ_{c.m.} = 90°) and 28.0 to 36.0 MeV (1973WH02: θ_{c.m.} = 88°). See also ^{6}Li in (1974AJ01). For reaction (a) see ^{6}He in (1974AJ01).
At E(^{7}Li) = 2.6 MeV, population of ^{12}C*(4.44, 15.11) is reported (1962BE24).
(1970BL09) had reported the observation of a capture resonance at E(^{3}He) = 1.74 MeV which subsequently decayed via ^{12}C*(15.11) and which was assumed to correspond to the first J^{π} = 0^{+}; T = 2 state in ^{12}C [E_{x} = 27.585 ± 0.005 MeV]. However, neither (1972HA63) nor (1972WA18) have been able to repeat this measurement: Γ_{3He}Γ_{γ}/Γ < 1.5 meV (1972WA18), < 2 meV (1972HA63). See also (1974HA1G). Excitation functions and angular distribution studies have been carried out by (1972BL17: E(^{3}He) = 1.0 to 6.0 MeV; γ_{0}, γ_{1}, γ_{2}), (1972LI29: 1.5 to 11 MeV; γ_{0}, γ_{1}, γ_{2}, γ_{3}), (1964BL12: 2 to 4.5 MeV; γ_{0}, γ_{1}) and (1974SH01: 3 to 21 MeV (γ_{2}), to 24 MeV (γ_{0}), to 26 MeV (γ_{1}, γ_{3})). Observed resonances are shown in Table 12.10 (in PDF or PS). ^{12}C*(28.2) appears to be formed by s and dwave capture. The γ_{0} and γ_{2} transitions to the 0^{+} states ^{12}C*(0, 7.7) are strong and show a similar energy dependence. A strong nonresonant contribution is necessary to account for the γ_{1} yield (1972BL17). The resonance structure reported by (1974SH01) appears to confirm the role of 3p  3h configurations for ^{12}C excitations somewhat above the giant resonance region. The γ_{3} yield is relatively unstructured (1972LI29, 1974SH01: to E(^{3}He) = 26 MeV).
Excitation functions for neutrons have been measured for E(^{3}He) = 1.2 to 9.9 MeV for several neutron groups: see (1968AJ02) for a listing of the earlier references. No sharp structure is observed but there is some suggestion from angular distribution data and excitation functions at forward angles for a broad structure (Γ ≈ 350 keV) at E(^{3}He) ≈ 2 MeV: E_{x} = 27.8 MeV (1965DI06, 1963DU12). The total cross section for ^{11}C production rises monotonically for E(^{3}He) = 0.60 to 1.15 MeV (1973SU07) and then shows a broad maximum, σ = 113 mb, at E(^{3}He) = 4.3 MeV (1966HA21: E(^{3}He) = 3.2 to 10 MeV). Polarization measurements have been carried out for E(^{3}He) = 2.1 to 3.9 MeV (1971TH15: n_{0}, n_{1}, n_{2+3}): the shapes of the measured angular distributions for n_{0} and n_{1} show very gradual changes with energy. It is suggested that a significant direct interaction contribution is present (1971TH15). See also (1970KR09) and ^{11}C. Excitation functions and angular distributions for protons (reaction (b)) have been measured for E(^{3}He) = 1.0 to 10.2 MeV for a number of proton groups: see (1968AJ02) for a listing of the earlier references. The yields of ten proton groups have been determined for E(^{3}He) = 0.50 to 1.10 MeV (θ = 110°): the yields increase monotonically (1971ST1H, 1973SU07). The excitation curves at higher energies show only a slow and smooth increase: see, e.g. (1960HI08). See also ^{11}B. The excitation function for reaction (c) has been measured from threshold to E(^{3}He) = 31 MeV (1974MO23).
The cross section for ground state tritons (reaction (b)) increases monotonically for E(^{3}He) = 2.5 to 4.2 MeV (1969OR01: θ = 40°) and then shows a broad maximum at E(^{3}He) ≈ 4.5 MeV (1967EA01: θ = 20°). For reaction (a) see (1967CR04). See also ^{9}B and ^{10}B in (1974AJ01).
The elastic scattering excitation function decreases monotonically for E(^{3}He) = 4.0 to 9.0 MeV (1967EA01: θ = 45°) and 15.0 to 21.0 MeV (1972MC01: θ_{c.m.} = 90°). At θ_{c.m.} = 111° a slight rise is observed for E(^{3}He) = 19 to 21 MeV (1972MC01). See also (1974BO38: E(^{3}He) = 1.2 to 2.5 MeV). Polarization measurements are reported at E(^{3}He) = 18 MeV (1972MC01) and 31.4 MeV (1971EN03). See also ^{9}Be in (1974AJ01).
Excitation functions at θ = 140° (reaction (a)) do not show resonant behavior for E(^{3}He) = 1.0 to 1.9 MeV (1970EH1A: α_{0}, α_{1}; unpublished work). For reaction (b) see ^{8}Be in (1974AJ01) and (1972TA04). See also (1971OS05; theor.).
The excitation functions for E(^{3}He) = 4 to 10 MeV (1969TA05: θ = 50°; 1972YO02: θ_{c.m.} = 32°, 90°) show some fluctuations. See also ^{6}Li in (1974AJ01).
Neutron groups have been observed to ^{12}C*(0, 4.4, 7.7, 9.6, (10.1), (10.8)). Angular distributions of neutron groups have been measured at many energies in the range E_{α} = 1.9 to 23 MeV: see (1968AJ02) for earlier references and (1969KL09: E_{α} = 1.75 and 1.96 MeV; n_{0}), (1970VA23: E_{α} = 2.55 to 7.87 MeV (n_{0}); 2.55 to 7.47 MeV (n_{1}); 4.36 to 7.47 MeV (n_{2})), (1972OB01: 3.21 to 6.44 MeV (n_{0}, n_{1}, n_{2}); 6.24 and 6.44 MeV (n_{3})) and (1968VE06: 6.79, 7.96, 8.91, 9.92 MeV; n_{0}, n_{1}, n_{2}). The mean life of ^{12}C*(4.4) [J^{π} = 2^{+}] is 57^{+23}_{17} fsec, Γ_{γ} = (11.5^{+5}_{3.2}) meV (1966WA10): see Table 12.9 (in PDF or PS). ^{12}C*(7.7) decays predominantly into ^{8}Be + α (see reactions 20 and 35), J^{π} = 0^{+}, Γ_{π}/Γ = (6.9 ± 2.1) × 10^{6} (1960AL04, 1972OB01). See (1959AJ76, 1968AJ02) for surveys of the earlier work. See also ^{13}C in (1976AJ04) and (1968LE24, 1969KL1C, 1969NO01, 1969ZI1A, 1970FO1C, 1970GE1A, 1972DA32, 1972DE10, 1973TY1A, 1973VI1C, 1973WE03) and (1968VA1E, 1969HO34; theor.).
At E(^{6}Li) = 23.8 MeV strong transitions are observed to ^{12}C*(0, 4.4, 7.7, 9.6, 14.1) (1970OG1A; unpublished). See also (1968JA08) and (1972RI1C; theor.).
At E(^{3}He) = 13 MeV neutron groups are observed to ^{12}C*(0, 4.4, 7.7, 16.1, 17.8) and to excited states at E_{x} = 23.53 ± 0.04 [Γ < 0.4 MeV] and 27.611 ± 0.020 MeV. The latter is formed with a 0° cross section of ≈ 200 μb/sr and is taken to be the first 0^{+}; T = 2 state of ^{12}C (1974GO23).
The (d, γγ) excitation function [via the J^{π} = 1^{+}; T = 1 state at E_{x} = 15.1 MeV] has been measured for E_{d} = 2.655 to 2.91 MeV. The nonresonant yield of 15 MeV γrays is due to direct capture process or to a very broad resonance: no sharp resonances are observed corresponding to the T = 2 state reported in reaction 4 [Γ_{d0}Γ_{γ}/Γ ≲ 0.2 eV] (1970BL09, 1974HA1G). Upper limits to the differential cross sections for γ_{0} and γ_{1} are 5 nb/sr and 50 nb/sr, respectively for E_{d} = 4.0 to 20.2 MeV (1971SH1E; prelim. results).
The thintarget excitation function in the forward direction in the range E_{d} = 0.3 to 4.6 MeV shows some indication of a broad resonance near E_{d} = 0.9 MeV. Above E_{d} = 2.4 MeV, the cross section increases rapidly to 210 mb/sr at 3.8 MeV, and then remains constant to 4.6 MeV (1954BU06, 1955MA76). The 0° excitation function for ground state neutrons shows no structure for E_{d} = 3.2 to 9.0 MeV (1967DI01). The excitation function for the neutrons to ^{11}C*(6.48) increases monotonically for E_{d} = 4.0 to 4.8 MeV (1972TH14). The branching ratios at 90° for the transitions to the ground states of ^{11}C and ^{11}B [n_{0}/p_{0}] have been measured for E_{d} = 1.0 to 2.0 MeV by (1973BR24). Polarization measurements have been carried out for E_{d} = 1.20 to 2.90 MeV (1968BR26: n_{0}) and 2.4 to 4.0 MeV (1972ME06: n_{0}, n_{1}, n_{2+3}). The transitions to ^{11}C*(0, 4.32 + 4.80) appear to involve a direct reaction mechanism (1972ME06). See also (1969DI08) and ^{11}C.
Absolute yields have been measured for various proton groups for E_{d} = 0.14 to 12 MeV: see (1968AJ02) and (1972AR31: E_{d} = 0.7 to 2.5 MeV; p_{0} → p_{3}) and (1970BL09: E_{d} = 2.605 to 2.960 MeV; p_{0} → p_{3}). See also (1970PO03). No clear resonance structure is observed. There is some indication that a broad resonance, corresponding to ^{12}C*(27.1) affects the p_{1} and p_{3} yields (1964BR1A). Upper limits for the partial widths (p_{0} → p_{3}) of the T = 2 state reported in reaction 4 are given by (1970BL09). See also (1972AH1A). For a study of the branching ratio n_{0}/p_{0} see reaction 14 (1973BR24). Polarization measurements have been carried out recently for E_{d} = 1.15, 1.40 and 1.85 MeV (1969DI08; p_{0}), 10 MeV (1969CU10: p_{0}) and 10 and 12 MeV (1970FI07, 1972FI1E: p_{0}) and 13.6 MeV (1967GO27: p_{0}). For earlier polarization studies [E_{d} = 6.9 to 21 MeV] see (1968AJ02). See also (1967GO27, 1967SA06), (1970DE35, 1973CO18; theor.) and ^{11}B.
The yield of elastically scattered deuterons has been measured for E_{d} = 1.0 to 2.0 MeV: resonances at E_{d} = 1.0 and 1.9 MeV are suggested by (1969LO01). Excitation functions for the deuterons to ^{10}B*(1.74, 2.16) [J^{π} = 0^{+}; T = 1 and J^{π} = 1^{+}; T = 0, respectively] have been measured at several angles for E_{d} = 4.2 to 16 MeV: they are characterized by rather broad, slowly varying structures. The ratio σ_{1.74}/σ_{2.15} varies from 0.69 ± 0.04% at E_{d} = 6.5 MeV to 0.16 ± 0.04% at E_{d} = 12.0 MeV corresponding, respectively, to isospin impurities of ≈ 2% and ≈ 0.5% (1974ST01). No resonance structure is observed in the elastic yield for E_{d} = 14.0 to 15.5 MeV (1974BU06). Polarization measurements are reported at E_{d} = 9, 10 and 11 MeV (1972FI1E, 1973FI1C) and at 15 MeV (1974BU06). See also ^{10}B in (1974AJ01).
For polarization measurements at E_{d} = 15 MeV involving ^{9}Be*(0, 2.43) and ^{9}B*(0, 2.36) see (1974LU06). See also ^{9}Be and ^{9}B in (1974AJ01).
Excitation functions have been measured for the α_{0} and α_{1} groups for E_{d} = 0.4 to 3.3 MeV: see (1968AJ02) for earlier references and (1968FR07: 0.5 to 2.0 MeV), (1968CO31: 0.8 to 2.5 MeV) and (1970BL09: 2.605 to 2.960 MeV). The α_{0} yield has also been measured for E_{α} = 4 to 12 MeV by (1971RE1D) and the yields to ^{8}Be*(16.6, 16.9) have been determined for E_{d} = 2.856 to 2.906 MeV by (1972AH1A; in 2 keV steps; unpublished). A number of broad maxima are observed in the excitation curves above E_{d} = 1 MeV. The α_{0} yield shows such a maximum at E_{d} = 1 MeV which (1968FR07) attribute to an swave resonance corresponding to a state with E_{x} ≈ 26.0 MeV, Γ ≈ 0.5 MeV. No evidence for the T = 2 state reported in reaction 4 was found in the α_{0} and α_{1} yield curves taken in 2 keV steps for 27.35 < E_{x} < 27.65 MeV (1970BL09). See also (1972AH1A). The relative populations of ^{8}Be*(17.6, 18.1) have been determined for E_{d} = 4 to 12 MeV (1970CA12): see ^{8}Be, reaction 38 (1974AJ01). For reaction (b) see (1968AS01, 1973RO28) and ^{8}Be in (1974AJ01). See also (1967LE1C, 1967NA11) and (1970KO01, 1970KO27, 1971LA25; theor.).
This reaction has been studied for E_{d} = 8 to 13.5 MeV (1964GE10).
Proton groups observed by (1958MO99, 1959AL96, 1962BR10) are displayed in Table 12.11 (in PDF or PS). Angular distributions of many of these groups have been measured for E(^{3}He) = 1.4 to 14 MeV: see (1968AJ02) for the earlier references and (1970BE1F). From studies of ^{10}B(^{3}He, pα)^{8}Be it is determined that ^{12}C*(7.7, 9.6, 10.8, 14.1, 16.1) have natural parity π = (1)^{J}, and that ^{12}C*(11.8, 12.7, 13.3), which decay only to ^{8}Be*(2.9) and not to the ground state, have unnatural parity: see Tables 12.8 (in PDF or PS) and 12.11 (in PDF or PS), and (1968AJ02). ^{12}C*(12.7) decays also by γemission: the cascade via ^{12}C*(4.4) is 15 ± 4%, the crossover transition is 85 ± 4% (1972AL03); Γ_{γ}/Γ_{α} = 2.5 ± 1% (1958MO99, 1959AL96). ^{12}C*(15.11) [J^{π} = 1^{+}; T = 1] decays by γemission to ^{12}C*(0, 4.4, 7.7, (10.3), 12.7): see Table 12.9 (in PDF or PS) (1972AL03). It is suggested by (1972AL03) that an isospinforbidden αdecay branch from ^{12}C*(15.11) to ^{8}Be*(2.9), which had been reported with an intensity of (1.2 ± 0.7)% in reaction 67, does not exist: the problem might have been an inaccurate determination of the intensity of the γbranch to ^{12}C*(12.7) by (1970RE09): see, however, (1974BA42) in reaction 67. ^{12}C*(16.11, 16.58) show decay to both ^{8}Be*(0, 2.9). The consequent assignment of natural parity is consistent with J^{π} = 2^{+} for the former but not with J^{π} = 2^{} for the latter. For ^{12}C*(16.11) observed values of Γ_{α0}/Γ are 0.05  0.12; the decay to 3α occurs rarely if at all (1966WA16). Reactions (c) and (d) have been studied by (1970BO39). The latter, at E(^{3}He) = 11 MeV, appears to proceed via a state in ^{12}C at E_{x} = 20.5 ± 0.1 MeV, which is suggested to be J^{π} = 3^{+}; T = 1. The relative intensities of the decays of ^{12}C states with 20 < E_{x} < 25 MeV via channels (c) and (d) is estimated. The α_{0} decay is very small, consistent with the expected population of T = 1 states (1970BO39). See also ^{8}Be in (1974AJ01), ^{13}N in (1976AJ04) and (1968KR02, 1970BE1F, 1972BE05, 1974AN19), (1967HO1C) and (1967PR1B; theor.).
At E_{α} = 21.2, 23.0 and 25.0 MeV angular distributions of the deuterons to ^{12}C*(0, 4.4) have been measured (1967AL16). The (dγ_{4.4}) angular correlations have been measured for E_{α} = 19 to 25 MeV (1972EL09). See also (1967SP09, 1973HA1Y, 1973SP1D), (1971BU1K, 1973ZE03; theor.) and ^{14}N in (1976AJ04).
At E(^{6}Li) = 4.9 MeV angular distributions have been obtained for the αparticles to ^{12}C*(0, 4.4, 7.7, 9.6). The population of ^{12}C*(11.8, 12.7) is also reported (1966MC05), as is that of ^{12}C*(15.11) [T = 1] (1964CA18: E(^{6}Li) = 3.8 MeV): the intensity ratio α_{15.1}/α_{12.7} = 3 ± 2%. See also (1969CO1D, 1970GI05).
Angular distributions involving ^{12}C^{*}_{4.4} + ^{12}C_{g.s.} and ^{12}C^{*}_{4.4} + ^{12}C^{*}_{4.4} have been measured at E(^{14}N) = 22.5 and 30 MeV (1969IS01). See also (1972VO02).
Angular distributions involving ^{14}N_{g.s.} + ^{12}C_{g.s.} and ^{14}N_{g.s.} + ^{12}C^{*}_{4.4} have been measured at E(^{16}O) = 30 and 32.5 MeV and also at 26 MeV for the double ground state transition (1969IS01). See also (1968OK06).
In view of the complexity of the available information on these three reactions, we will first summarize the recent experimental results and then review the evidence for the parameters of ^{12}C states observed as resonances. (a) In the range 4 MeV < E_{p} < 14.5 MeV σ(γ_{0}) is dominated by the giant dipole resonance at E_{p} = 7.2 MeV (E_{x} = 22.6 MeV, Γ_{c.m.} = 3.2 MeV), while the giant resonance in γ_{1} occurs at E_{p} ≈ 10.3 MeV (E_{x} = 25.4 MeV, Γ_{c.m.} ≈ 6.5 MeV): see (1964AL20). A study of the giant dipole resonance region with polarized protons (E_{p} = 6 to 14 MeV) sets new limits on the configuration mixing in the γ_{0} giant resonance. The analysis of γ_{1} is more complicated: the asymmetry results are consistent either with a single J^{π} = 2^{} state or with interference of pairs of states such as (1^{}, 3^{}), (2^{}, 3^{}) and (1^{}, 2^{}) (1972GL01). Measurements of differential cross sections at 90° (E_{p} = 13 to 22 MeV), of angular distributions (E_{p} = 7 and 14 to 21 MeV), and of total cross sections (E_{p} = 14 to 21 MeV) have been reported by (1970BR1J, 1972BR26) for γ_{0}, γ_{1} and γ_{3} [to ^{12}C*(0, 4.4, 9.6)]: disagreement is reported with the cross section values reported by (1964AL20). The γ_{2} yield to ^{12}C*(7.7) exhibits a peak at E_{p} ≈ 14.3 MeV with a cross section ≈ 2.3% that of γ_{0}. The γ_{3} yield shows two large asymmetric peaks at E_{p} = 12.5 and 13.8 MeV with Γ ≈ 0.7 and 2.5 MeV, respectively, as well as a weaker structure near E_{p} = 9.8 MeV (1971SN1A: E_{p} = 6 to 18 MeV; abstracts). (1969KE02: E_{p} = 13 to 21 MeV) report a broad peak in the γ_{0} cross section at E_{p} = 14.8 MeV [E_{x} = 29.5 MeV]. The previously reported resonance in γ_{0} at E_{p} = 20.1 MeV [see (1968AJ02)] does not exist: see (1969KE02, 1972BR26). No evidence is seen in this reaction for the J^{π} = 0^{+}; T = 2 state reported in reactions 4 and 12 (1974HA1G: search for γ_{12.5} + γ_{15.1}, that is (0^{+}; 2) → (1^{+}; 1) → (0^{+}; 0)). Work on other resonances is discussed below. See also the reviews by (1968BR1D, 1968SC1B, 1972HA1Y, 1973GL1C, 1973HA1Q, 1973SU1E, 1974HA1N), (1972CA1H) and (1969MA22, 1970GO41, 1973BA05, 1973HA1X, 1973SU03; theor.). (b) Excitation functions for α_{0} have been measured recently for 7.50 < E_{p} < 18.9 MeV: no marked structure is observed above E_{x} = 28 MeV (1972TH1C: Ph.D. thesis; (1969TH1B, 1971TH1F); abstracts). See also ^{8}Be in (1974AJ01) and (1968CH01, 1971GU23). (c) This reaction has been studied for E_{p} = 0.15 to 9.5 MeV. It proceeds predominantly by sequential twobody decay via ^{8}Be*(0, 2.9): see ^{8}Be in (1974AJ01) and (1968CH01, 1968GI03, 1969QU01, 1970CO03, 1971KO22, 1971YA13, 1972CH35, 1972DZ10, 1972HU04, 1972MI1J, 1972TR07, 1972VO01, 1973PR1C). See also (1969PH1B), (1967CO29, 1967EN1A, 1967FL12, 1968LA1C, 1969LA1B, 1970PA10), (1969GO13, 1969SA1B, 1970GI1C, 1970GO1J, 1970GO33, 1970GO49, 1970KO01, 1970KO1K, 1970KO27, 1970MC25, 1970MC1T, 1970SC01, 1971GO20, 1971LA25, 1972GO1N, 1972KO1J, 1973GO35, 1973KO11, 1973KO38; theor.) and (1974LI1M; applied). The parameters of the observed resonances are displayed in Table 12.12 (in PDF or PS). The following summarizes the information on the lowlying resonances: for a full list of references see (1968AJ02). E_{p} = 0.16 MeV [^{12}C*(16.11)]. This is the J^{π} = 2^{+}; T = 1 analog of the first excited states of ^{12}B and ^{12}N. The γdecay is to ^{12}C*(0, 4.4, 9.6): the angular distribution of γ_{3}, together with the known αdecay of ^{12}C*(9.6), fix J^{π} = 3^{} for the latter (1961CA13). A new measurement of the (p, γ) and (p, α) resonant cross sections yields 125 ± 16 μb and 38.5 ± 3.2 mb, respectively, based on Γ_{c.m.} = 6.7 keV. Γ_{γ} and Γ_{p} for ^{12}C*(16.11) are then 21.7 ± 3.3 eV and 21.7 ± 1.8 eV, respectively (1974AN19). See also Table 12.9 (in PDF or PS). E_{p} = 0.67 MeV [^{12}C*(16.58)]. The proton width [Γ_{p} ≈ 150 keV] indicates swave protons and therefore J^{π} = 1^{} or 2^{}. This is supported by the near isotropy of the two resonant exit channels, α_{1} and γ_{1}. The α_{1} cross section indicates 2J + 1 ≥ 5: therefore J^{π} = 2^{}. [This is consistent with the results of an α  α correlation study via ^{8}Be*(2.9) (1972TR07)]. The γ_{1} E1 transition has M^{2} ≈ 0.01 W.u., suggesting T = 1 (1957DE11, 1965SE06). (1962BL10) report a γ branch to ^{12}C*(12.71) (≈ 6% of the intensity of the γ_{1} transition). Such a branch may also be present for ^{12}C*(17.23). See also (1973PR1C). E_{p} = 1.4 MeV [^{12}C*(17.23)]. (2J + 1) Γ_{γ0} ≥ 115 eV. This indicates J^{π} = 1^{}, with T = 1 most probable (1965SE06). J^{π} = 1^{} is also required to account for the interference at lower energies in α_{0} and γ_{0}: see (1957DE11) and is consistent with the α  α correlation results of (1972TR07). Two solutions for Γ_{p} are possible; the larger (chosen for Table 12.12 (in PDF or PS)) is favored by elastic scattering data (1965SE06). E_{p} = 2.0 MeV [^{12}C*(17.76)]. The resonance in the yield of α_{0} requires natural parity, the small αwidths suggest T = 1. For J^{π} = 1^{} or 3^{} the small γwidths would be surprising; J^{π} = 2^{+} would lead to a larger anomaly than is observed. J^{π} is then 0^{+}; T = 1 (1965SE06). E_{p} = 2.37 MeV [^{12}C*(18.13)]. Seen as a resonance in the yield of 15.1 MeV γrays: σ_{R} = 0.77 ± 0.15 μb, Γ_{c.m.} = 600 ± 100 keV, (2J + 1) Γ_{γ} ≥ 2.8 ± 0.6 eV. The results are consistent with J^{π} = 1^{+}; T = 0, but interference with a nonresonant background excludes a definite assignment (1972SU08). E_{p} = 2.62 MeV [^{12}C*(18.36)]. The resonance for α_{0} requires natural parity; the presence of a large P_{4} term in the angular distribution requires J ≥ 2 and l_{p} ≥ 2. The assignment J^{π} = 3^{} is consistent with the data (1965SE06, 1972CH35, 1972VO01, 1974GO21). E_{p} = 2.66 MeV [^{12}C*(18.40)] is not seen here: see ^{11}B(p, p). E_{p} = 3.12 MeV [^{12}C*(18.80)]. The angular distribution of γ_{0} indicates E2 radiation, J^{π} = 2^{+}. This assignment is supported by the angular correlation in the cascade γ_{1} and by the behavior of σ(α_{0}); T = 1 is suggested by the small Γ_{α} (1965SE06). The structure near E_{p} = 3.5  3.7 MeV [^{12}C*(19.2, 19.4)] seems to require at least two levels. The large Γ_{γ0} requires that one be J^{π} = 1^{}; T = 1 and interference terms in σ(α_{0}) require the other to have even spin and even parity: J^{π} = 2^{+}; T = 0 is favored (1963SY01, 1965SE06). Levels at E_{p} = 4.93 and 5.11 MeV, seen in σ(γ_{1}) (1955BA22) also appear in σ(α_{1}), but not in σ(α_{0}). Angular distributions suggest J^{π} = 2^{+} or 3^{} for the latter [^{12}C*(20.64)]; the strength of γ_{1} and absence of γ_{0} favors J^{π} = 3^{}; T = 1 (1963SY01). The first seven T = 1 states in ^{12}B and ^{12}C have been identified by comparing reduced proton widths obtained from this reaction and reduced widths obtained from the (d, p) and (d, n) reactions: see Table 12.13 (in PDF or PS) (1971MO14, 1974AN19).
Excitation functions have been reported for E_{p} = 2.6 to 11.5 MeV. They are characterized by numerous peaks: see Table 12.14 (in PDF or PS). The positions of these appear to correspond with ^{11}B(p, α)^{8}Be and with some of the (γ, n) and (γ, p) structure, suggesting that resonances, and not fluctuations, are involved. Angular distributions do not change as rapidly as might be expected from the pronounced structure in the excitation function (1965OV01). The strength of the pronounced peak at E_{p} = 6.03 MeV (E_{x} = 21.49) appears to demand J ≥ 4 (1961LE11). The polarization transfer coefficient has been measured for E_{p} = 7 to 15 MeV: the strong influence of resonances is apparent (1974LI1J). See also (1974MA07; theor.). Polarization measurements have been carried out for E_{p} = 7 to 11 MeV (1965WA04) and at 24.5 MeV (1972MO41). See also (1973BA05; theor.), ^{11}C and (1968AJ02).
A pronounced anomaly in the elastic scattering is observed near E_{p} = 0.67 MeV at all angles; the level is therefore formed by swaves. The 0.3 to 1.0 MeV results are well accounted for by two resonances: E_{p} = 0.67 MeV, swave, J^{π} = 2^{}, Γ = 0.33 MeV, Γ_{p}/Γ = 0.5, and E_{p} = 1.4 MeV, J^{π} = 1^{} (1957DE11). Higher energy structure in the yields of reactions (a) and (b) are displayed in Table 12.14 (in PDF or PS) (1955BA22, 1965SE06, 1971SA1H). Excitation functions for p_{0} and p_{1} have been measured for E_{p} = 7.5 to 21.5 MeV: no pronounced structure is observed above E_{x} = 28 MeV (1972TH1C: Ph.D. thesis; (1969TH1B, 1971TH1F); abstracts). Polarization measurements have been reported at E_{p} = 1.9 to 3.0 MeV (1974DE45: p_{0}), 3.5 to 10.5 MeV (1971SA1H; prelim. report; p_{0}, p_{1}), 30.3 MeV (1969KA15, 1971LO05; p_{0}, p_{1}, p_{2}) and 155 MeV (1968GE04; p_{0}, p_{1}, p_{2}, p_{4}). See also (1965HU10, 1968RI1J, 1972RE06) and (1969WA11, 1971BL1E; theor.). For reaction (c) see (1971RA26). See also ^{11}B and ^{10}Be in (1974AJ01).
See ^{10}B in (1974AJ01).
Reported neutron groups are displayed in Table 12.15 (in PDF or PS). Angular distributions have been reported for many energies in the range 0.5 < E_{d} < 11.8 MeV: see (1968AJ02) for a listing of the earlier references and (1970BU15: 5.5 MeV; n_{0}, n_{1}), (1967FU07: 6 MeV; see Table 12.15 (in PDF or PS)), (1974AN19: 6 MeV; n to ^{12}C*(15.1, 16.1); see Table 12.13 (in PDF or PS)), (1971MU18: 11.8 MeV; see Table 12.15 (in PDF or PS)). See (1971MU18) for a discussion of the problems involved in comparing spectroscopic factors obtained in this reaction and in the (^{3}He, d) reaction [reaction 30]. Angular correlations of neutrons and γrays have been studied at many energies: see (1968AJ02) for the earlier references and (1968TE03: 1.6 to 3.3 MeV for γ_{4.4}; 2.9 and 3.3 MeV for γ_{15.1}) and (1972TH14: 4.0 to 4.8 MeV; γ_{4.4}, γ_{15.1}). In the range E_{d} = 1.0 to 5.5 MeV, two slow neutron thresholds are observed at 1.627 ± 0.004 MeV (E_{x} = 15.109 ± 0.005 MeV) and near 4.1 MeV (broad; E_{x} = 17.2 MeV) (1955MA76). At the lower threshold, 15.1 MeV γrays are observed: E_{d} = 1.633 ± 0.003 MeV, Γ < 2 keV (1958KA31) [E_{x} = 15.110 ± 0.003 MeV]. A study of the angular distributions and energy spectra of αparticles from the decay of ^{12}C states shows that the 12.71 and 11.83 MeV states decay sequentially via ^{8}Be; the former via ^{8}Be*(2.9), the latter 90% via ^{8}Be*(2.9) and 10% via ^{8}Be(0). There is some evidence that the 10.84 MeV state decays primarily to ^{8}Be(0). J^{π} = 3^{} for the 9.64 MeV state is favored on the basis of the angular distribution of the αparticles to ^{8}Be(0). There is no evidence for direct 3α decay of ^{12}C levels in the range E_{x} = 9 to 13 MeV, nor does ^{12}C*(10.3) appear to participate in this reaction (1965OL01). See also ^{13}C in (1976AJ04) and (1970MI1G, 1970YA11; theor.).
Observed deuteron groups are displayed in Table 12.15 (in PDF or PS). Angular distributions have been measured at E(^{3}He) = 5.1 to 44 MeV: see (1968AJ02) for the earlier references and (1969MI15: E(^{3}He) = 10, 12 and 18 MeV), (1968BO26: 11 MeV), (1971RE03: 44 MeV). ^{13}N*(15.1) [T = 3/2] has been observed to decay to ^{12}C*(9.6, 10.8) with branching ratios of 9.6 ± 1.4% and 16.4 ± 3.6%, respectively. The upper limit to ^{12}C*(12.7) is ≈ 5% (1974AD1D).
Angular distributions have been measured at E_{α} = 15.1, 18.3 and 24.9 MeV (1972VA34: t_{0}; and t_{1} at 24.9 MeV), 27 MeV (1969TE1B: t_{0}, t_{1}; unpublished) and 46 MeV (1969FO1C: t_{0} → t_{3} and t to ^{12}C*(12.7); abstracts). See also (1968AJ02). The (t_{1}, γ) angular correlations have been measured for E_{α} = 21.2 to 25.0 MeV (1972EL09). See also (1973ZE03; theor.).
See (1968ST12).
Angular distributions have been measured for the ground state transition at E(^{14}N) = 41, 77 and 113 MeV: they show damping of the oscillations with increasing energy (1971LI11). See also (1973DE35; theor.).
Angular distributions have been measured at E(^{16}O) = 27, 30, 32.5, 35 and 60 MeV for the transitions ^{15}N_{g.s.} + ^{12}C_{g.s.}, ^{15}N^{*}_{6.3} + ^{12}C_{g.s.}, ^{15}N_{g.s.} + ^{12}C^{*}_{4.4} and ^{15}N_{g.s.} + ^{12}C^{*}_{9.6} (the latter at E = 60 MeV only) (1972SC03): at the highest energy the ratio θ^{2}/θ^{2}_{g.s.} for the transition ^{11}B_{g.s.} + p → ^{12}C is 0.12 and 0.05, respectively for ^{12}C*(4.4, 9.6). See also (1968OK06), (1969BR1D, 1972MO1E) and (1968VA1D, 1969KA1G, 1970AN1D, 1970SC1G, 1972BO21, 1973DE1W, 1973DE35, 1973OS03, 1974OS1A; theor.).
The decay is mainly to ^{12}C_{g.s.}; branching ratios to ^{12}C*(4.4, 7.7, 10.3) are shown in Table 12.16 (in PDF or PS). All the observed transitions are allowed. The halflife is 20.41 ± 0.06 msec [see Table 12.2 (in PDF or PS) of (1968AJ02)]. ^{12}C*(7.7) is of particular interest for helium burning processes in stars [see (1968AJ02)]. The fact that the βdecay is allowed indicates J^{π} = 0^{+}, 1^{+} or 2^{+}; it decays primarily by αemission eliminating J^{π} = 1^{+}, and requiring 0^{+} (1957CO59). (1973BA73) have measured the Q of the αdecay of ^{12}C*(7.7) to be 379.6 ± 2.0 keV. When this result is combined with the Q determined from accurate measurements of the E_{x} of ^{12}C*(7.7), the "best" value is Q = 380.1 ± 1.1 keV. This value, together with previously measured values of Γ_{π}, Γ_{π}/Γ and Γ_{rad}/Γ [see Table 12.9 (in PDF or PS)] lead to Γ_{rad} = 3.41 ± 1.12 meV and to a mean lifetime for the destruction of helium by the [ααα] process of 2.59 x 10^{8}ρ^{2}T^{3}_{9}exp(4.411/T^{9}) sec^{1} (1973BA73). A search for transitions to ^{12}C*(12.7) has been unsuccessful (1967AL03). See also reaction 63. For asymmetry measurements see (1967PF02, 1973ST1P, 1974PO05). See also ^{12}C, reaction 28 in (1968AJ02), and (1971MI06, 1973CH16, 1973MIYZ, 1974PO05). See also (1974AL11), (1968DA1J) and (1969BL1D, 1969CH1A, 1969CH1F, 1969MO1F, 1970ST04, 1971BL06, 1971KI04, 1971KI11, 1971LA21, 1971LI1F, 1971LI1H, 1971WI18, 1971WI1C, 1972AR04, 1972EM02, 1972OC01, 1972WI28, 1972WI1C, 1973BO09, 1973EM1B, 1973HA49, 1973KU1D, 1973KU1N, 1973TO14, 1973WI11, 1973YO04, 1974BO18, 1974HO1D, 1974WI1L, 1975GR03; theor.).
Resonance scattering and absorption by ^{12}C*(15.11) have been studied by many groups: see Table 12.15 (in PDF or PS) in (1968AJ02). The partial widths are displayed in Table 12.9 (in PDF or PS). The scattering angular distribution indicates dipole radiation (1959GA09), the azimuthal distribution of scattered polarized radiation indicates M1 (1960JA01) and the large Γ_{γ} indicates T = 1. The branching ratio for the cascade decay via ^{12}C*(4.4) is 3.6 ± 0.7% (1970AH02). Elastic scattering to ^{12}C*(4.4, 16.1, 17.2) has also been observed. See also (1968AJ02) and Table 12.20 (in PDF or PS). At higher energies, elastic scattering studies show the giant resonance peak at ≈ 24 MeV. A considerable tail is visible, extending to > 40 MeV (1959PE32). See also reaction 37, (1969MO1H, 1971ME1B) and (1968SI1A; theor.).
The total absorption, mainly (γ, n) + (γ, p), is dominated by the giant resonance peak at 23.2 MeV, Γ = 3.2 MeV [σ_{max} = 19.8 mb (1965WY02)] and by a smaller structure at 25.6 MeV, Γ ≈ 2 MeV (σ_{max} ≈ 8 mb): see (1968AJ02) [Tables 12.16 (in PDF or PS), 12.17 (in PDF or PS)] for a detailed listing of the earlier references and results, and see (1973AH1A, 1974BE2B). See also (1967DO1A, 1969BE92). Total absorption cross sections have also been measured at E_{γ} = 84 to 662 keV by (1968RA1D), at 7.28 and 7.65 MeV by (1969MO1H), at 10 to 140 MeV by (1970AH02, 1972AH1B, 1973AH1A) and at 250 to 1000 MeV by (1972MI1K, 1974HO15). See also Table 12.16 (in PDF or PS) in (1968AJ02). The (γ, n) cross section shows a giant resonance centered at about 22.5 MeV, Γ ≈ 3 MeV (σ_{max} ≈ 8 mb), a secondary maximum at 25.5 MeV, Γ ≈ 2 MeV, and a long tail: see (1968AJ02). The giant resonance peak is rather flattopped with several small fine structure bumps across the top (E.G. Fuller, private communication): see (1966CO09, 1966FU02, 1966LO04, 1971IS09, 1972VA32, 1973BE2F, 1973IS1A, 1974BE2B). The (γ, n_{0}) cross section has been measured at 90° for 21 < E_{x} < 40 MeV and compared with the (γ, p_{0}) cross section (1968WU01): the isospin mixing averages about 2% in intensity and shows structure at the giant resonance. [See the reviews by (1970HA1F, 1973HA1Q).] Angular distributions of n_{0} measured over the giant resonance region indicate that the main excitation mechanism is of a 1p_{3/2} → 1d_{5/2} E1 single particle character. No significant E2 strength is observed (1968RA21, 1970JU1C, 1973JU1C). The fraction of transitions to the ground state and to excited states of ^{11}C has been measured at E_{bs} = 24.5 to 42 MeV: see ^{11}C (1970ME17), reaction 38 and the discussion in (1973DI1C). For polarization measurements see (1973NA1K) and (1968AJ02). For a listing of recent cross section measurements see Table 12.17 (in PDF or PS). The cross section for reaction (b) has been measured for E_{γ} = 35 to 130 MeV. The (γ, 2n) cross section is very much smaller than that for (γ, n): the highest value is 0.15% of the maximum value for reaction (a) in the energy range E_{γ} = 20 to 140 MeV (1970KA37). See also (1967AN11, 1969DE12, 1971JO1E, 1973MO1G, 1973VA12), (1972BU1J, 1973CO1N, 1973HA1Q) and (1968PA1H, 1969ER1A, 1969GA1J, 1969GO1D, 1969MA22, 1969UB01, 1970GO41, 1970MU1D, 1971AN08, 1971BA97, 1971BI01, 1971WA27, 1972BI11, 1973BA05, 1973BE1W, 1973BI1K, 1973MA1T, 1973MS01, 1973MS02, 1973SR1B, 1973SU03, 1973WE1U, 1974CA1R, 1974FI03, 1974GI1A; theor.). For applied work see (1973AL1G).
The photoproton cross section exhibits two broad peaks, the giant resonance peak at 22.4 MeV, Γ = 3.2 MeV, σ_{max} = 13 mb [see Table 12.19 (in PDF or PS) in (1968AJ02)], and a second broad peak at 25.1 MeV, in addition to some fine structure. In contrast with the giant resonance peak in the (γ, n) cross section, the (γ, p) cross section shows a sharp peak in the center of the broad giant resonance peak. Above 24.5 MeV, the ground state (γ, p) and (γ, n) excitation functions have the same shape up to at least 36 MeV (E.G. Fuller, private communication). The (γ, p) results of (1968FR12, 1968FR14, 1969CA22) are in good agreement with those of (1964AL20) for the inverse reaction, ^{11}B(p, γ_{0})^{12}C [see reaction 25], when the population of ^{11}B*(4.4, 5.0) is taken into account: the required cross sections for the (γ, p_{2}) and (γ, p_{3}) processes peak at 1.5 mb at 29 and 30 MeV, respectively (1973DI1C, 1974DI17). The fraction of transitions to the ground and excited states of ^{11}B at several energies in the range E_{bs} = 24.5 to 42 MeV has been measured by (1970ME17): most of the transitions are to ^{11}B_{g.s.} and the excited state transitions appear to originate from localized E_{x} regions. See ^{11}B and the discussions in (1970HA1F, 1973DI1C). Proton spectra and angular distributions have also been measured at E_{bs} = 50 to 80 MeV (1968MA32, 1969MA23), 98.5 MeV (1968MA19) and 80, 120, 285 and 1140 MeV (1970AN34). The ratio of deuterons to protons has been determined at 1140 MeV by (1972AN1M). For polarization measurements see (1970TO09). See also (1968AJ02) for the earlier measurements and reaction 44. For reactions (b) and (c) see (1971GR1X, 1972AB1H, 1974BO47, 1974DE1U, 1974EP02) and the "Pion capture and pion reactions" section here. See also (1970WO1E, 1971AN04, 1971EG03, 1971EG02, 1971GO32, 1971IR1C, 1972TO22, 1973DO13, 1974BO47, 1974DO08, 1974DO07), (1972BU1J, 1973CO1N, 1973HA1Q) and (1969GA1J, 1969GO1D, 1969MA22, 1969UB01, 1970GO41, 1970MU1D, 1971BA97, 1971BI01, 1971GI1D, 1972AK02, 1972BI11, 1972WE1G, 1973BA05, 1973BE1W, 1973DE1Y, 1973LA1M, 1973MS01, 1973MS02, 1974SE02; theor.)
Cross sections and angular distributions of the deuterons corresponding to transitions to ^{10}B_{g.s.} and/or low excited states have been measured at E_{γ} ≈ 40 MeV: the results are consistent with E2. There is some evidence also for the excitation of higher states of ^{10}B via nonE2 transitions (1972SK08). The high apparent threshold for reaction (a) is thought to reflect the presence of continuum states of ^{10}B with a high parentage in ^{12}C (1964SH1B). For E_{bs} = 90 MeV, the ratio of yields of deuterons to protons is ≈ 2%, for particle energies 15 to 30 MeV. For higher particle energies, the ratio decreases (1962CH26). See also (1969AN1F, 1969AN10, 1971AN04, 1971AN15, 1972AN09, 1972AN1M) for excitation functions to 1400 MeV, and (1968AJ02). For reaction (b) see (1968TA10, 1969TA11) and (1973KO1H; theor.).
The yield of tritons has been measured for E_{γ} = 35 to 50 MeV by (1967KR05). See also (1969AN1F, 1972AN09). For reaction (b) see (1969TA11).
The cross section exhibits broad peaks at about 18 MeV and ≈ 29 MeV; a pronounced minimum occurs at 20.5 MeV: to what extent the peaks have fine structure is not clear: see (1964TO1A) and (1968AJ02). For E_{γ} < 22 MeV, transitions are mainly to ^{8}Be_{g.s.} and ^{8}Be*(2.9) with the g.s. transition dominating for E_{γ} ≲ 14 MeV. For E_{γ} > 26.4 MeV, ^{8}Be (T = 1) levels near 17 MeV are strongly excited (1955GO59). Alpha energy distributions show surprisingly strong E1 contributions below E_{γ} ≈ 17 MeV (1955GO59, 1964TO1A).
The yield of 0.48 MeV γrays from the decay of ^{7}Be, formed in reaction (b), shows a resonance at E_{γ} ≈ 29.5 MeV, σ = 0.9 ± 0.2 mb. It is assumed to be the dipole state with a 5p  5h character (J^{π} = 0^{+}) based on ^{12}C*(7.66) considered to be relatively pure 4p  4h (1969OW01). For work on the γinduced spallation of ^{12}C see (1968TA10, 1969TA11). See also (1968DI1B, 1969DI18, 1971DI1F) and (1969ER1A; theor.). For older work on these reactions see (1968AJ02).
The nuclear charge radius of ^{12}C, R_{rms} = 2.462 ± 0.022 fm (1973FE13). Other values include R_{rms} = 2.445 ± 0.015 fm (Fermi model), 2.453 ± 0.008 fm (shell model) (1972JA10). See also (1969BE21, 1970BR1C, 1970SI08, 1971BE25, 1973EN1E, 1973KL12, 1973TH1B) and (1968AJ02). Elastic scattering has been studied up to 4 GeV: see (1968AJ02) for the earlier references and (1972JA10: E_{e} = 20 → 80 MeV), (1973KL12: E_{e} = 374.6 MeV), (1970SI08: E_{e} = 374.5 and 747.4 MeV) and (1971ST10: E_{e} = 1 to 4 GeV). ^{12}C states observed in the inelastic scattering are displayed in Table 12.18 (in PDF or PS) (1963BO36, 1965BI1B, 1967CR01, 1968BE1H, 1968DO08, 1968ST20, 1969GU05, 1969TO01, 1970AN1C, 1970LI02, 1970ST10, 1970TO13, 1971BE51, 1971NA14, 1972SP1C, 1973CH16, 1974CE01). See also (1968PR01, 1969VA10). The variation of the form factor F(q^{2}) with momentum transfer yields unambiguous assignments of J^{π} = 2^{+}, 0^{+} and 3^{}, respectively for ^{12}C*(4.4, 7.7, 9.6) (1960BA38, 1964CR11, 1967HA1F). Form factors for ^{12}C*(0, 4.4, 14.1) have been measured by (1971NA14). The isospin mixing between ^{12}C*(12.71) and (15.11) [both J^{π} = 1^{+}; T = 0 and 1, respectively] has been measured by (1974CE01): β = 0.19 ± 0.01 or 0.05 ± 0.01. Inelastic scattering of the giant resonance has been studied by many groups: see (1968AJ02) for the earlier work and Table 12.18 (in PDF or PS). The longitudinal form factors show ^{12}C*(16.1, 18.6, 20.0, 21.6, 22.0, 23.8, 25.5) while the transverse form factors show ^{12}C*(15.1, 16.1, 16.6, 18.1, 19.3, 19.6, 20.6, 22.7, (25.5)) (1970AN1C, 1970TO13, 1971YA03, 1972AN03). See also (1969TO10). ^{12}C*(19.3) may be the expected giant magnetic quadrupole state, J^{π} = 2^{}: see (1968AJ02) and (1968BE1H, 1968DR01). See also (1970GR27; theor.). (1974OB01) has measured the most probable energy loss for E_{e} = 50 and 100 MeV. See also (1968DE25, 1969CA1C, 1970AN1G, 1970DE04, 1971TI03, 1973ME1K), (1968GO1J, 1972THZF, 1973BI1A, 1973TH1B), reaction 44 and (1968AN1B, 1968BO1J, 1968CI1C, 1968FR1E, 1968HE1C, 1968HO1B, 1968KE10, 1968MA1N, 1968RA1B, 1969CH01, 1969CH1A, 1969CI1A, 1969DE14, 1969DO1D, 1969FU1F, 1969HE1F, 1969KA1H, 1969KU1C, 1969UB01, 1969VI02, 1970CH1H, 1970CH1J, 1970CI1B, 1970DO1F, 1970DO1G, 1970DO1H, 1970DO1A, 1970FR1E, 1970GO41, 1970GU12, 1970HI1C, 1970JA08, 1970LI18, 1970LI1P, 1970MC1D, 1970ON1B, 1970SA1B, 1970SP1C, 1971CI03, 1971DE1T, 1971DU06, 1971FR13, 1971MO1Q, 1971TA13, 1972AB19, 1972AN03, 1972AN15, 1972BE1X, 1972BO01, 1972EL11, 1972FR06, 1972GU25, 1972LE45, 1972OC01, 1972PA32, 1972ST35, 1972SU01, 1972UB01, 1973AL14, 1973BA05, 1973BO1Q, 1973DO1H, 1973FO1G, 1973FO1F, 1973GA19, 1973KU1N, 1973MA07, 1973MU04, 1973RI1A, 1973ROYN, 1973SI13, 1973SI1P, 1973SU03, 1973TA1F, 1974AB05, 1974BA1Z, 1974DZ06, 1974DZ05, 1974FR12, 1974IN05, 1974SI03; theor.).
Electron spectra in the region of large energy loss show a broad peak which is ascribed to quasielastic processes involving ejection of single nucleons from bound shells: see (1968AJ02). A study of e'  p coincidences for E_{e} = 550  600 MeV reveals peaks corresponding to ejection of 1p and 1s protons: the results are consistent with observations in (p, 2p) (1964AM1C, 1967AM03). At E_{e} = 497 MeV, the proton spectrum is dominated by an l = 1 transition to ^{11}B_{g.s.} (1974BE12). See also (1971BU26). The data obtained by (1974BE12) do not satisfy the sum rule of (1972KO01). The quasielastic scattering cross section has also been measured at E_{e} = 199.5 MeV (1969GU05), 500 MeV (1971MO06, 1974WH05) [the Fermi momentum is 221 ± 5 MeV/c (1971MO06)], 1 to 4 GeV (1971ST10) and 2.5 and 2.7 GeV (1974HE20, 1974KO21). See also (1967AM1A, 1968BO46, 1968DE25, 1969BE1L, 1969DE20, 1970DE04, 1970HI1F, 1970VY01, 1970WO1E, 1971EG03, 1971EG02, 1971SH09, 1972BE1U, 1972VL1A, 1973HE1H, 1974BA70, 1974SI1G) and (1967AM1C, 1972RA1E). Absolute cross sections for reaction (b) have been measured for E_{e} = 20 to 30 MeV, using both electrons and positrons (1972KU27). See also (1973MO1G, 1973VO09). For reaction (c) see (1970EN1A). For reactions (d) and (e) see (1969TI04, 1970TI03, 1971TI03, 1971ST10, 1973HE1H) and the "Pion capture and pion reactions" section here. See also (1968BO1J, 1968BO1D, 1968CI1B, 1968DE1F, 1968MA1M, 1968WA1D, 1969DR05, 1969MO1G, 1969ST1E, 1969VY1A, 1969WA1E, 1970CI1C, 1970EP1A, 1970PA1H, 1970SI23, 1971BO1M, 1971CI1A, 1971PA42, 1971SH18, 1972AM1C, 1972AN03, 1972RA20, 1972RA18, 1972WE14, 1973BA2M, 1973BA71, 1973CI1A, 1973HI03, 1973JO1H, 1973SH02, 1974HA14, 1974KN1C, 1974ME24; theor.).
Angular distributions of the elastic scattering and for the inelastic scattering to ^{12}C*(4.4, 9.6, 15.0) have been measured at E_{π} = 120 to 280 MeV (1970BI1A). [Not all groups were measured at the seven energies in the above interval. ^{12}C*(9.6) represents the group of levels with 9.6 ≤ E_{x} ≤ 10.8 and ^{12}C*(15.0) those with 15.1 ≤ E_{x} ≤ 17.2 (1970BI1A).] Observation of 4.4 MeV γrays at E_{π} = 73 MeV leads to a cross section ratio (π^{}/π^{+}) of 1.23 ± 0.22. The cross section is 14.5 ± 3.0 mb for π^{+}. The population of ^{12}C*(15.11) was not observed in either reaction (1970HI10). The involvement of ^{12}C*(4.4) in reaction (c) has been studied by (1973AS1A). See also the "GENERAL" section here, (1971TH05, 1975PI1E) and (1971RO14, 1974JA1F, 1974NI08; theor.).
Elastic and inelastic scattering to ^{12}C*(4.4, 7.7, 9.6, 10.3, 10.8, 11.8) have been studied at many energies up to 350 MeV: see (1968AJ02) and Table 12.19 (in PDF or PS). Angular correlations of (n_{1}, γ_{4.4}) have been studied at E_{n} = 13.9 MeV (1973DE45) and 15.0 MeV (1971SP01), and at 14  14.7 MeV [see (1968AJ02)]. The spinflip probability for the transition to ^{12}C*(4.4) has been studied at E_{n} = 7.48 MeV (1971MC1K, 1972MC20) and at 15.0 and 16.9 MeV (1973TH08, 1974ME29). The shape of the angular distribution of the probability at E_{n} = 7.48 MeV is similar to that measured by (1964SC07) in the (p, p') reaction at E_{p} = 10 MeV (1972MC20); while that at E_{n} = 16.9 MeV is similar to that measured by (1969KO07) at E_{p} = 20 MeV (1974ME29). At E_{n} = 14.4 MeV reaction (b) involves ^{12}C*(9.6, 10.8, 11.8, 12.7). The decay of ^{12}C*(11.8) leads to an assignment of J^{π} = 1^{} (1964BR25, 1971DO1K, 1975AN01, 1975AN02). [See, however, Table 12.8 (in PDF or PS)]. See also (1966MO05, 1968BE1J). See also ^{13}C in (1976AJ04), (1968BR05, 1968KO1A, 1969PE1C, 1969RO1F, 1970BR1K, 1970MA1J, 1972DE31, 1974DR1C), (1968CA1A, 1968CH35, 1968TI1B, 1969AL1C, 1969DU1B, 1969OL03, 1970CA13, 1970SH14, 1971CH01, 1971MI07, 1972IK01, 1972JO11, 1972MO45, 1974CH1X; theor.) and (1969TR1A; astrophys. problems).
Angular distributions of elastically and inelastically scattered protons have been measured at many energies up to E_{p} = 1040 MeV: see Table 12.22 (in PDF or PS) in (1968AJ02) for the earlier work and Table 12.20 (in PDF or PS) here. Angular distributions at E_{p} = 20 MeV (1963DI16, 1970BL03) and 46 MeV (1967PE05) show that a large quadrupole deformation exists: β_{2} = 0.72 (1972DE13) and 0.6 (1967SA13), respectively. Table 12.21 (in PDF or PS) shows the information on excited states of ^{12}C. The angular distribution for ^{12}C*(7.7) is best described by double quadrupole excitation via ^{12}C*(4.4). ^{12}C*(14.1) is identified as the 4^{+} rotational state (1967SA13). The values E_{x} = 7656.2 ± 2.1 keV (1971AU16), 7655.9 ± 2.5 keV (1971ST22) obtained for the 0^{+} second excited state of ^{12}C lead to a substantial change in the reaction rate for heliumburning nucleosynthesis: see (1971AU16). The inplane and spinflip pγ_{4.4} angular correlations have been measured at 20 MeV. The substate cross sections were determined: these show a more pronounced structure than does the total inelastic cross section to ^{12}C*(4.4). The M = 0 cross section is the most diffraction like. Agreement with the compound nucleus DWBA predictions is poor (1972TE01). The spinflip probability in the scattering to ^{12}C*(4.4) has been studied at E_{p} = 8.00 to 8.30 MeV (1972BE15), 12 to 14 MeV (1970KO15), 12, 13, 14, 15 and 20 MeV (1969KO07), 15.9 and 17.35 MeV (1971WI16) and 26.2 and 40 MeV (1969KO13). See also (1973SA1N). (1972BE15) find that the interference between the resonant and the background spinflip is large: see ^{13}N in (1976AJ04). At E_{p} = 26.2 and 40 MeV the observed spinflip is almost entirely accounted for by distortions in the entrance and exit elastic channels, due to the spinorbit term in the optical model potential (1969KO13). For polarization measurements see (1970LI19, 1975GL1C) and ^{13}N in (1976AJ04). See also (1971GA42, 1973TH1A, 1974AL1G, 1974BR1J, 1974DA1Q, 1974GA30, 1974OB1C, 1975PI1E), (1964KA1A, 1967LE13, 1968BA1K, 1968CH35, 1968GL1A, 1968KO26, 1968LE1D, 1968LI1B, 1968NE1B, 1968TA1D, 1968TA1E, 1968TI1B, 1969BA06, 1969BY1A, 1969HA07, 1969KO1H, 1969LE03, 1969MA1G, 1969NE1A, 1969OL03, 1969PE1E, 1969TA1D, 1969TI02, 1969WA11, 1970BA1F, 1970CA13, 1970CZ1A, 1970DA17, 1970GU15, 1970HA1J, 1970KO1L, 1970KR1E, 1970KU1C, 1970SA06, 1970SH01, 1970SH14, 1971AH03, 1971CH01, 1971FR1L, 1971HA31, 1971IN05, 1971JA16, 1971LE01, 1971MI07, 1971MO18, 1971RA36, 1971SH18, 1971SI11, 1971SI37, 1972AN12, 1972AU1A, 1972BA2E, 1972JO11, 1972IK01, 1972SI19, 1972SO03, 1972ST35, 1973AL14, 1973AU05, 1973DO10, 1973FR08, 1973GE1E, 1973KA04, 1973MA2B, 1973MI19, 1973SI37, 1973VA18, 1974AL1H, 1974BE22, 1974BR06, 1974IN04, 1974IN06, 1974IN07, 1974JA1F, 1974KU20, 1974SC1K, 1974ST02, 1973TE1B; theor.) and (1969TR1A; astrophys. questions).
At E_{p} = 56.5 MeV, ^{12}C*(20.3 ± 0.5) is excited and then decays to ^{11}B_{g.s.} (1969EP01). At E_{p} = 385 MeV and estimate of the momentum distribution of the protons bound in ^{12}C has been obtained. The results are consistent with a model in which the nuclear core is essentially a spectator. Distortion effects are mainly of an absorptive nature (1969JA05). At E_{p} = 1.0 GeV, the process is essentially quasifree (1970SI01, 1972CO11). See also (1971PA1H). Small angle multiple scattering of 600 MeV protons has been measured by (1972HU12). The angular correlation to ^{11}B(0) has been measured at E_{p} = 49.5 MeV by (1971HA61). See also (1968AJ02) for earlier references, ^{11}B, (1968PE1A, 1971LA16, 1971LO25), (1969JA1F, 1969VO1E, 1972RA1E) and (1968DE1G, 1968JA1E, 1969GU1G, 1969JA1D, 1969KO1J, 1969MC13, 1970FL1B, 1970KR1E, 1971JA11, 1971JA16, 1971MC26, 1971SH18, 1971WI15, 1971YO1E, 1972AB1G, 1972CH1L, 1972JA1C, 1972PE04, 1972PI11, 1972ST29, 1972WI16, 1973ER19, 1973FR09, 1973GU1D, 1973JA01, 1973JO1H, 1973SH02, 1974BH1B, 1974PI01; theor.). For reaction (b) see (1968PA05: E_{p} = 450 MeV). See also (1971TH05: pbar, pbar n), (1970TH1F) and (1972AB1G; theor.). For reaction (c) see (1970BA1T, 1971AZ01, 1972AZ03, 1972BO17, 1973KO1M) and (1968RO1F, 1974ZH01; theor.). At E_{p} = 56.5 MeV, reaction (d) proceeds primarily by sequential αdecay: initially ^{12}C*(19.7 ± 0.5, 21.1 ± 0.3, 22.2 ± 0.5 and 26.3 ± 0.5 MeV) are formed. The states, which therefore must have natural parity and a significant T = 0 admixture, subsequently decay to ^{8}Be_{g.s.} [^{12}C*(22.2, 26.0)] or ^{8}Be*(2.9) [^{12}C*(19.7, 21.1, 26.3)] (1969EP01). At E_{p} = 160 MeV, knockout, sequential decay and spallation processes are observed (1970GO12). See also (1969HO1K, 1971GA1J, 1972MA62, 1972YA1B, 1973HO1R, 1973TH1A) and ^{8}Be and ^{9}B in (1974AJ01). For spallation studies see (1968KO1E, 1969DA1D, 1969ED01, 1969KO1G) and ^{13}N in (1976AJ04). See also (1968ED1A). For pion production see (1970DO04), (1971IN1A, 1971RE12, 1972KE1F, 1973DI1G, 1974MI11; theor.), the "Pion capture and pion reactions" section here and ^{13}C in (1976AJ04).
The angular distribution of elastically and inelastically scattered deuterons has been studied at many energies to E_{d} = 650 MeV: see (1968AJ02) for the older references and Table 12.22 (in PDF or PS) here. DWBA analysis of the distributions at E_{d} = 80 MeV leads to β_{l} = 0.47 ± 0.05 and 0.35 ± 0.06 for ^{12}C*(4.4, 9.6), respectively (1971DU09). E_{x} of ^{12}C*(4.4) is 4440.5 ± 1.1 keV: the average of this value and of the one determined in (p, p') (Table 12.21 (in PDF or PS)) gives 4439.5 ± 1.0 keV (1974JO14). The isospin mixing of ^{12}C*(12.71, 15.11) [both J^{π} = 1^{+}; T = 0 and 1, respectively] has been measured for E_{d} = 27.2 and 28.0 MeV. The ratio of the cross sections for the population of the T = 1 and 0 states is (7.0 ± 1.2) x 10^{3}. [In a remeasurement of this quantity (1975LI1K) find ≈ (1.1 × 10^{2}). Angular distributions for the two states were obtained at E_{d} = 24.1, 26.2, 27.5 and 28.8 MeV (1975LI1K).] This leads to β^{2} = 0.011 ± 0.003 (1972BR27: see also reactions 66, 67, 76). For a study of the distribution of ionic charge when ^{12}C recoils in elastic scattering at E_{p} = 10 MeV, see (1971WO10). Reaction (b) has been studied, in a kinematically complete experiment, at E_{d} = 5.00 to 5.50, 9.20 and 9.85 MeV by (1970SA1K, 1973SA03). An increase in yield is observed for all spectra in the region of low relative protonneutron energy where both rescattering and sequential decay leading to the ^{1}S_{0} final state interaction are possible. Due to the probable superposition and interference of different reaction mechanisms, it is apparently not possible to evaluate how much spin singlet and spin triplet interaction is involved (1973SA03). See, however, (1973SH04). Studies of reaction (b) are also reported at E_{d} = 5.1 to 6.25 MeV (1973SH04), 5.4 and 6.0 MeV (1968BO02) and 5.5 to 6.5 MeV (1970VA1K, 1972VA10). See also ^{13}C and ^{13}N in (1976AJ04) and (1972GE1G). See also ^{14}N in (1976AJ04), (1968VA12, 1968VE11, 1968VE1C, 1969KO1B, 1969PH1B, 1971PU01, 1972HE1E) and (1968DU01, 1968LY1A, 1968ME1E, 1968NO1C, 1969OL03, 1969TA1D, 1969VE09, 1970EL16, 1970OH1C, 1971GR54, 1971KO42, 1971KO43, 1971SI24, 1972BE54, 1972DM01, 1972ST1J, 1973HE1J, 1974AS1D, 1974IA02, 1974IN07; theor.).
Angular distributions of elastically scattered tritons have been determined at E_{t} = 1.0 to 1.75 MeV (1962GU01, 1969HE08), 1.11 to 3.40 MeV (1969ET01 and private communication), 1.75 and 2.10 MeV (1969SI12), 6.4, 6.8 and 7.2 MeV (1964PU01), 12 MeV (1965GL04, 1966GL1B), 16 and 20 MeV (1972KE02) and 20.04 MeV (1974JA25). See also (1968HO1C) and (1971KA04; theor.).
Angular distributions of ^{3}He ions have been measured at many energies in the range E(^{3}He) = 2 to 217 MeV: see reaction 43 in (1968AJ02) for the older measurements and Table 12.22 (in PDF or PS), here, for the newer ones. DWBA analyses seem to be inadequate: complete coupled channels analyses appear to be necessary to explain the data; see, e.g., (1972AS03, 1973SI11). Angular distributions of the ^{3}He groups to ^{12}C*(15.11, 16.11, 16.58, 19.57) have been compared with those for the tritons to ^{12}N*(0, 0.96, 1.19, 4.25) in the analogue reaction ^{12}C(^{3}He, t)^{12}N: the correspondence is excellent and suggests strongly that these are T = 1 isobaric analogue states (1968BA1E, 1969BA06: E(^{3}He) = 49.8 MeV). See also Tables 12.13 (in PDF or PS) and 12.23 (in PDF or PS), ^{12}N and (1970AR05, 1974WI16). The (^{3}He', γ_{1}) reaction plane angular correlation has been measured at E(^{3}He) = 17 MeV as a function of gammaray angle for 43 ^{3}He scattering angles. The spinflip probability was also determined, and the quadrupole deformation was found to be β_{2} = 0.60 (1968AS03, 1972AS03). See also (1971PA1K, 1974YA10). For polarization measurements see ^{15}O in (1976AJ04). See also (1967AR17, 1967BA1D, 1970JA1E, 1970KA1D) and (1968LE1G, 1968PA1F, 1969RA1B, 1970CA1G, 1973BR1L; theor.).
Angular distributions have been measured at many energies to E_{α} = 166 MeV: see Table 12.24 (in PDF or PS) in (1968AJ02) and Table 12.22 (in PDF or PS) here. Alphaparticle groups have been observed to many ^{12}C states: see Tables 12.22 (in PDF or PS) and 12.23 (in PDF or PS) (1972FA07). J^{π} assignments have also been suggested for ^{12}C states with 9.6 ≤ E_{x} ≤ 39.3 MeV on the basis of their decay into 3 αparticles: see (1973JA02; E_{α} = 90 MeV). See also (1969BA06). Angular correlation measurements (α_{1}γ_{4.4}) have been carried out at E_{α} = 10.2 to 10.5 MeV (1972KE18), 18.0 to 24.0 MeV (1968KL07), 19 MeV (1972AS03), 19.3 to 25.3 MeV (1972EL09), 22.75 MeV (1970HA15), 32.5 MeV (1972BU09) and 41 MeV (1971BA64): the relative population of magnetic substates has been studied by (1970HA15, 1972BU09). See also (1968AJ02). The quadrupole deformation, β_{2}, is 0.29 ± 0.02 (1971SP08), 0.46 (1973SM03); β_{3} = 0.24 (1973SM03). See also (1971BE60, 1972EE1A). Measurements of the radiative widths yield Γ_{rad}/Γ = (4.2 ± 0.2) × 10^{4} [Γ_{rad} ≡ Γ_{γ} + Γ_{e}^{±} is then 3.7 ± 1.2 meV] for ^{12}C*(7.7) (1974CH03) and Γ_{rad}/Γ < 4.1 × 10^{7} [Γ_{rad} < 14 meV] for ^{12}C*(9.6) (1974CH32): see also Table 12.9 (in PDF or PS). The value for Γ_{rad} for ^{12}C*(7.7) implies a 45% faster rate for the (ααα) astrophysical process (1974CH03). See also (1973HA1Y, 1974MA2C). For total cross sections for formation of various ^{12}C states, see ^{16}O in (1971AJ02, 1977AJ02) and (1973SP1D). For polarization measurements, see ^{16}O in (1977AJ02). See also (1967HA1G, 1968CA11, 1968ED1B, 1968GA1D, 1968RA1C, 1968SH1D, 1968SH1E, 1968TO1D, 1969BU1D, 1969PI02, 1971MU1H, 1971TA30, 1971TE10, 1972DM01, 1973AL14, 1973BR1K, 1973BU1G, 1973DM01, 1973KU08, 1973SI1M, 1974PI11, 1974GO1U, 1974HO19, 1974WA02; theor.) and (1969TR1A; astrophys. questions). Reaction (b) at E_{α} = 25 MeV appears to involve ^{12}C*(7.66, 9.64) (1969DO02, 1969DO03). See also (1974RU06). See (1968YA02, 1969PI1B, 1970KE1B, 1970EI05, 1970PI1D, 1973RU09, 1974DO1G) for other studies of the (α, 2α) reaction with E_{α} up to 700 MeV. See also ^{8}Be in (1974AJ01), (1971GA1J) and (1968BA1H, 1970BU1C, 1970MI12, 1972AV04, 1972MI05; theor.).
The elastic scattering in reaction (a) has been studied at E(^{6}Li) = 4.5 to 13 MeV (1972PO07), 20 MeV (1968BE1K, 1972WA31), 24.5 MeV (1968DA20), 28 MeV (1972BA52), 30 MeV (1971CH1P, 1971DA33), 34 and 36 MeV (1973SC26; also ^{12}C*(4.4)) and 36.4 and 40 MeV (1974BI04). See also (1964OL1A). (1974BI04) have also measured the inelastic angular distributions to ^{12}C*(4.4, 7.7, 9.6, 10.8, 11.8, 12.7, 13.4, 14.1) and have calculated deformation parameters under various assumptions. Two step processes are important in the excitation of ^{12}C*(7.7, 14.1) (1974BI1H). See also (1971DA1J) and (1968NO1C, 1971OS02, 1974AS1D; theor.). The elastic scattering in reaction (b) has been studied at E(^{7}Li) = 4.5, 5.8, 9.0, 11.0 and 13.0 MeV (1972PO07), 15 and 21.1 MeV (1972WE08) and at 36 MeV (1973SC26). At 36 MeV the angular distributions corresponding to ^{12}C_{g.s.} + ^{7}Li^{*}_{0.48}, ^{12}C^{*}_{4.4} + ^{7}Li_{g.s.} and ^{12}C^{*}_{4.4} + ^{7}Li^{*}_{0.48} have also been studied (1973SC26).
Elastic scattering angular distributions have been obtained at E(^{12}C) = 12, 15, 18 and 21 MeV (1970BA49).
Angular distributions have been measured for reaction (a) at E(^{10}B) = 18 MeV (1968VO1A, 1969VO10: to g.s.) and 100 MeV (1973BI1J, 1974BI1E: to ^{12}C*(0, 4.4, 7.7, 9.6, 10.8, 11.8, 12.7, 13.4, 14.1, 14.8). Twostep processes appear to be involved in the excitation of ^{12}C*(7.7, 14.1) (1974BI1E). See also (1974AS1D; theor.). Angular distributions for reaction (b) have been studied at E(^{12}C) = 15, 17, 20 and 24 MeV (1974BO15: to g.s.) and 87 MeV (1971LI11: to g.s.), and at E(^{11}B) = 28 MeV (1968VO1A, 1969VO07, 1969VO10: to g.s., 4.4; and to several ^{11}B states). A consistent description of the elastic data at E(^{12}C) = 15 to 24 MeV is obtained by including the elastic transfer of a 1p_{1/2} hole (1974BO15). See also (1972SC1Q) and (1970AN1D, 1973DE35; theor.). For yield measurements see ^{22}Na and ^{23}Na in (1973ENVA) and (1974DA1P).
Angular distributions have been measured at E(^{12}C) = 18.8 to 37.6 MeV (1973EM03: g.s. + g.s., g.s. + 4.4, 4.4 + 4.4), 40 to 60 MeV (1973WI09: g.s. + g.s., g.s. + 4.4, 4.4 + 4.4), 70 MeV (1971KO11: g.s.) and at 87 MeV (1971LI11: g.s.). At E(^{12}C) = 114 and 174 MeV differential cross sections have been measured for the population of ^{12}C*(0, 4.4, 7.7, 9.6, 14.1, 19.6). The population of ^{12}C^{*}_{4.4} + ^{12}C^{*}_{4.4} is also reported (1973AN22). The relative population of elastic and inelastic channels is very energy dependent: see ^{24}Mg in (1973ENVA) and (1968WI1C, 1973EM03, 1973GO01, 1973RE13, 1973RE12, 1973WI09, 1974RA1J, 1974RA1K, 1974SH16, 1974SP06, 1974VO09, 1975OB1B). See also (1969BR1D, 1969BR1G, 1969HE06, 1970BR1G, 1973BR1C, 1973PE1D, 1973ST1A, 1974ST1L), (1968IM1A, 1969IM1A, 1969MI1B, 1969VO1E, 1970AN1D, 1970MI1D, 1970MO35, 1970PR12, 1971MC1J, 1971RI1F, 1971RI1G, 1972AR11, 1972FI11, 1972GO1G, 1972MA74, 1972MI1H, 1972RE1K, 1972RI19, 1973BO06, 1973CO1X, 1973FI07, 1973JA22, 1973MO1J, 1973SC1K, 1974FI1G, 1974GA1L, 1974KO1N, 1974PA08, 1974WA02; theor.) and (1968AR1C, 1970NA1F, 1971BA1A, 1972MI1H, 1973AR1E, 1973CL1E, 1973GR1G, 1974AR2B, 1974CO1L, 1975SW1A; astrophys. questions).
Elastic angular distributions in reaction (a) have been studied at E(^{12}C) = 15 and 19 MeV (1971BO52, 1971BO1U, 1972BO68), at 20 to 36 MeV (1972CH1H, 1973CH1L; and also to ^{12}C*(4.4) and various states in ^{13}C) and at 87 MeV (1971LI11). See also (1970GO1B, 1971WI1J, 1973BR1C, 1973GO01, 1973SC1B) and ^{13}C in (1976AJ04). Elastic angular distributions in reaction (b) are reported at E(^{12}C) = 12 to 20 MeV (1972BO68). For yield measurements, see (1972BO68, 1973FE03, 1974CR03) and ^{24}Mg and ^{25}Mg in (1973ENVA). See also (1970VO1D, 1973BA2K, 1973DE35, 1973MC1J, 1973SA1K, 1973VO04, 1974GA1L, 1974IM1B; theor.).
Angular distributions have been measured at E(^{14}N) = 21 MeV (1971BO1U, 1971VO01: to g.s.), 22.5 MeV (1969HE06: to g.s.), 65, 84 and 88 MeV (1971KO11: to g.s.), 78 MeV (1970VO02: to g.s., 4.4) and 155 MeV (1974BI1E: to g.s., 4.4, 7.7, 9.6, 10.8, 11.8, 12.7, 13.4, 14.1; see also reaction 54). See (1968AJ02) for earlier measurements. See also ^{14}N in (1976AJ04), (1974AN36) and (1974NA1G). For yield measurements see ^{26}Al in (1973ENVA) and (1974JO1J, 1974ST1N). See also (1969BR1D) and (1972MA74, 1974GA1L; theor.).
Elastic angular distributions have been measured at E(^{16}O) = 20, 24, 35 and 42 MeV (1968VO1A, 1969VO10), 26, 30 and 32.5 MeV (1969KR03), 27 to 53 MeV (1972MA29, 1972MA1P), 36 MeV (1971OR02) and 65 and 80 MeV (1973GU12). At E(^{16}O) = 65 and 80 MeV, angular distributions involving ^{12}C*(0, 4.4) and various states of ^{16}O have been studied by (1973GU12): see ^{16}O in (1977AJ02). A kinematically complete study of reaction (b) has been carried out at E(^{16}O) = 58.3 MeV. The main process appears to involve (^{12}C + α) corresponding to an excited state of ^{16}O with E_{x} ≈ 10 MeV. Formation and decay of compound states in ^{24}Mg are also involved (1974WI05). See also (1973ENVA). For studies of the yields of these reactions see (1968MA1J, 1969VO10, 1972MA29, 1972ST09, 1973CH1N, 1973MA1N, 1974MA1L, 1974WI05). See also ^{28}Si in (1973ENVA). See also (1970JA1B), (1969BR1D, 1969BR1G, 1969HE06, 1970BL1E, 1970BR1G, 1971GA1P, 1972GA1E, 1973PA1J, 1973PE1D, 1973ST1A), (1969KA1G, 1969RO1G, 1969VO1E, 1970AN1D, 1970CL1E, 1971DA30, 1972BA73, 1972CH1E, 1972GO1G, 1972MA1U, 1972RI03, 1973DE40, 1973FE1G, 1973LO02, 1973SA1K, 1974GA1L, 1974WA02, 1975KI01; theor.) and (1970NA1F, 1971WO1E, 1973AR1E, 1973CL1E, 1974CO1L, 1975SW1A; astrophys. questions).
The elastic scattering angular distributions in both (a) and (b) have been measured at E = 35 MeV (1967GO1A). See also ^{18}O in (1978AJ03) and (1971BE60, 1974CH1Q).
Elastic scattering angular distributions have been measured at E(^{19}F) = 40, 60 and 68.8 MeV (1968VO1A, 1969VO10, 1972SC03). See also (1970AN1D, 1970BL1E; theor.).
The elastic scattering angular distribution has been measured at E(^{12}C) = 37 MeV (1974VA18). See also ^{32}S in (1973ENVA).
The decay is mainly to the ground state via an allowed transition. Branching ratios to other states of ^{12}C are displayed in Table 12.24 (in PDF or PS). The halflife is 10.97 ± 0.04 msec: see Table 12.28 (in PDF or PS) in (1968AJ02). Since transitions to ^{12}C*(g.s., 4.4) are allowed J^{π}(^{12}N) = 1^{+}. Recent measurements of the ratios of the branching ratios, ^{12}N/^{12}B, for the decays to ^{12}C*(4.4) is 1.52 ± 0.06 (1972AL31), 1.74 ± 0.08 (1974MC11). Using R = 1.63 ± 0.11, and other data, (1974MC11) find that the asymmetry in the decay to the excited state is δ_{4.44} = 0.013 ± 0.066 and that δ_{g.s.} = 0.1155 ± 0.0085. See also (1973KU1D; theor.). ^{12}C*(12.7), populated in an allowed transition, decays primarily to ^{8}Be*(2.9) [J^{π} = 2^{+}]; the absence of decay to ^{8}Be_{g.s.} is in agreement with the assignment J^{π} = 1^{+} (1966SC23). The ft values for the βtransitions to ^{12}C*(12.7, 15.1) agree well with shellmodel calculations of (1965CO25). The agreement strongly suggests a close relation between ^{12}C*(12.7) [J^{π} = 1^{+}; T = 0] and ^{12}C*(15.1) [J^{π} = 1^{+}; T = 1]. See also (1971MI06, 1973CH16, 1973MIYZ). See also (1968DA1J) and (1969BL1D, 1969CH1A, 1969CH1F, 1970JA1K, 1970ST04, 1971BL06, 1971KI04, 1971KI11, 1971LA21, 1971LI1F, 1971LI1H, 1971WI18, 1971WI1C, 1972EM02, 1972OC01, 1972WI28, 1972WI1C, 1973EM1B, 1973HA49, 1973TO14, 1973YO04, 1974HO1D, 1974WI1L, 1974WI1Q, 1975GR03; theor.).
At E_{bs} = 28 MeV, 4.4 and 15.1 MeV γrays have been observed corresponding to the population of ^{12}C*(4.4, 15.1), while at E_{bs} = 21 MeV only ^{12}C*(4.4) is excited (1971MU11). See also (1971WI1N), (1973KI1J; theor.) and ^{13}C in (1976AJ04).
Angular distributions of the d_{0} and d_{1} groups to ^{12}C*(0, 4.4) have been measured at E_{p} = 8 and 12 MeV (1966GL01), 17 MeV (1961BE12), 50 MeV (1970SC02) and 54.9 MeV (1968TA08). In addition angular distributions have also been measured for the groups to ^{12}C*(12.7, 15.1, 16.1) at the two higher energies (1968TA08, 1970SC02). ^{12}C*(14.1) is not excited, consistent with J^{π} = 4^{+} (1970SC02, 1974PA01). At E_{p} = 62 MeV, (1974PA01) report the excitation of states with E_{x} = 15112 ± 5, 16110 ± 5 [< 20], 17760 ± 20 [80 ± 20], 18800 ± 40 [80 ± 30], 21500 ± 100 [< 200] and 22550 ± 50 [< 200] keV [the numbers shown in the brackets are Γ_{c.m.}, in keV]: l_{n} = 1 for all states except ^{12}C*(21.5) and (22.55) for which l_{p} = (1) and ≠ 1, respectively. Spectroscopic factors are derived by (1968TA08, 1970SC02, 1974PA01). At E_{p} = 17 MeV (1969CO06) give the ratio of σ(p, d)/σ(p, dbar) to the ground state of ^{12}C as 17. (1971OT02) suggest, however, that a part of the apparent (p, dbar) cross section may be due to ^{12}C + n final state interaction through ^{13}C*(10.75). In a kinematically complete experiment at E_{p} = 7.9 to 12.5 MeV, it is found that sequential decay via states in ^{13}C and ^{13}N is strongly involved in reaction (b). Near E_{p} = 12.5 MeV there is some indication of sequential decay via singlet deuteron formation (1971OT02). See also (1967SP09, 1970VA1K) and ^{13}C, ^{13}N and ^{14}N in (1976AJ04).
Angular distributions have been obtained at E_{d} = 0.41 to 0.81 MeV (1971PU01: t_{0}), 1.0 to 2.7 MeV (1970LI1E, 1971LI1K: t_{0}), 2.2 and 3.3 MeV (1954HO48: t_{0}), 8 and 12 MeV (1966GL01: t_{0}, t_{1}), 12.1, 13.3 and 14.0 MeV (1968TE04: t_{0}, t_{1}), 13.6 MeV (1973ZA06: t_{0}, t_{1}), 14.8 MeV (1960MA10: t_{0}, t_{1}, t_{2}), 15 MeV (1974LU06) and 28 MeV (1972BR27). In the latter experiment (1972BR27) have studied the triton groups to ^{12}C*(12.7, 15.1, 16.1) [J^{π}; T = (1^{+}; 0), (1^{+}; 1) and (2^{+}; 1), respectively] and the ^{3}He groups, in the analogue reaction, to ^{12}B*(0, 0.95) [J^{π} = 1^{+}; T = 1 and J^{π} = 2^{+}; T = 1, respectively]. The relative yield to ^{12}C*(15.1) is greater than that to its analogue, ^{12}B_{g.s.}, while the yields to the 2^{+} states are in good agreement. The value of β required to give the observed ratio of yields for the 1^{+} states is 0.13 [in good agreement with the (d, d') results: see reaction 49]: the chargedependent matrix element is then 250 ± 50 keV (1972BR27). See also ^{15}N in (1976AJ04), (1967SP09, 1969DE1H) and (1969LI1D; theor.).
Angular distributions have been measured at many energies up to E(^{3}He) = 45 MeV: see (1968AJ02) for the earlier references and (1971BO26: 1.5 to 5.3 MeV; α_{0}, α_{1}, α_{2}) and (1968AR12: 19.1, 27.3, 35.7, 36.8 MeV; α_{0}, α_{1}, α_{2}, α_{3} and α to ^{12}C*(12.7, 15.1, 16.1)). Angular correlations of αparticles and 4.4 MeV γrays have been studied at E(^{3}He) = 4.5 MeV (1962HO13) and for αγ_{15.1} at 9.4 and 11.2 MeV (1969TA09). See also (1975MA2J). Attempts have been made using this reaction (1970AR30, 1970RE09, 1974BA42) and reactions 49 and 66 to study the T mixing between the 1^{+} states ^{12}C*(12.71, 15.11). Reported values for Γ_{α}/Γ for ^{12}C*(15.11) are 1.2 ± 0.7% (1970RE09, 1970RE1F), 6.0 ± 2.5% (1970AR30), 4.1 ± 0.9% (1974BA42). The (1974BA42) value was obtained by observing the decay αparticles in reaction (b): adopting this value, and using the other parameters for the decay of ^{12}C*(15.11) [see Table 12.9 (in PDF or PS)] leads to Γ_{α} = 1.8 ± 0.3 eV. If this isospin forbidden αwidth is the result of mixing between the two 1^{+} states via a chargedependent interaction, the matrix element is 340 ± 60 keV (1974BA42). (1970RE09) have measured branching ratios for the decays of ^{12}C*(12.7, 15.1): see Table 12.9 (in PDF or PS). See also ^{16}O in (1977AJ02).
At E(^{7}Li) = 34 MeV angular distributions have been observed for the reactions to ^{12}C*(0, 4.4) + ^{7}Li*(g.s., 0.48) and ^{8}Li*(0, 0.95) in all combinations. While ^{12}C*(0, 4.4) are dominant in the two spectra, ^{12}C*(7.7, 9.6) and, in reaction (a) at E(^{6}Li) = 36 MeV, ^{12}C*(12.7) are also populated (1973SC26).
Angular distributions have been obtained for reaction (a) at E(^{16}O) = 14, 17 and 20 MeV (1968KN1A, 1971BA68: ^{12}C_{g.s} + ^{17}O*(g.s., 0.87)), 41.7 and 46.0 MeV (1973DE21). See also ^{28}Si in (1973ENVA) and (1974BE1J; theor.). For reaction (b) see (1974CH1Q). Ground state angular distributions for reaction (c) have been measured at E(^{18}O) = 15, 20 and 24 MeV (1971BA68, 1971KN05). See also (1974CH1Q).
Angular distributions have been measured at E_{p} = 14.5 MeV (1971CU01: t_{0}), 18.5 MeV (1963LE03: t_{0}) and 39.8 MeV (1970OL1B, 1973HO10: t_{0}, t_{1}). At E_{p} = 50.5 MeV the excitation of a T = 2 state with E_{x} = 27.595 ± 0.020 MeV is reported by (1970NE1A, 1971NE1B, 1971NE1E; unpublished results). This state has also been observed at E_{p} = 54 MeV as has another narrow state at E_{x} = 29.6 ± 0.1 MeV. The angular distribution of the tritons to the lower state is consistent with L = 0; that for the higher state is rather featureless (D. Ashery, private communication). [See also reaction 24 in ^{12}B.] See also (1971KA04; theor.).
Angular distributions leading to the ground states in reaction (a) have been measured at E(^{16}O) = 20, 25 and 30 MeV (1973SC24). For reaction (b) see (1972EY01) and ^{20}O in (1978AJ03).
See (1970TH01, 1972GE11), ^{13}C and ^{14}N in (1976AJ04), and (1973KI05; theor.).
Angular distributions of the t_{0} group have been measured at E_{n} = 14  15 MeV: see (1968AJ02). The γray from ^{12}C*(4.4) has been seen: E_{γ} = 4436 ± 5 keV (1971NY03). See also ^{15}N in (1976AJ04) and (1971MI1H).
At E_{p} = 46 MeV the transitions to ^{12}C*(0, 4.4) have been studied by (1970WE1J, 1971WE05). See also ^{14}N in (1976AJ04).
Angular distributions have been studied at E_{p} = 7.53, 8.03, 9.54 and 10.54 MeV (1970ME30: g.s.), 20.5, 24.3, 29.4, 34.6, 40.1 and 44.6 MeV (1974PI05: g.s., 4.4), 39.8 MeV (1973HO10: g.s., 4.4) and 50 MeV (1970SC02: g.s., 4.4, 12.7, 14.1, 15.1, 16.1). The results of (1970SC02) strongly indicate J^{π} = 4^{+} for ^{12}C*(14.1). See also ^{15}O in (1970AJ04, 1976AJ04), (1968SH11, 1968TO1E) and (1970CH1E; theor.).
Observed αparticle groups are shown in Table 12.23 (in PDF or PS) (1956DO41, 1965PE17, 1965SC12, 1972FA07). Angular distributions have been measured at many energies up to E_{d} = 28.5 MeV: see (1968AJ02) for the earlier work and (1969GO14: 1.0  3.1 MeV; α_{0} → α_{3}), (1971AR41: 1.70, 2.30, 2.90 MeV; α_{0}, α_{1}, α_{2}), (1967BO37: 2.29  5.76 MeV; α_{0}, α_{1}), (1969CU08: 10.5 MeV; α_{0} → α_{3}), (1970SC02: 15 to 20 MeV; α_{0}, α_{1} and α to ^{12}C*(12.7, 14.1)), (1968SC1C: 17 MeV; α_{1} → α_{3} and α to ^{12}C*(12.7, 14.1)), (1968MA1K: 20 MeV; α_{0} → α_{3} and α to ^{12}C*(12.7, 14.1)) and (1967VI03: 28.5 MeV; α_{0}, α_{1}. At E_{d} = 40 MeV the upper limits for the ratio of the cross sections to ^{12}C*(15.11) and ^{12}C*(12.71) are ≈ 0.3% for θ_{lab} = 6° to 10° and 0.5% at 40° and 50°: these results by (1974VA15) imply a lower isospin mixing between these two 1^{+} states than suggested by the work of (1972BR27): see reactions 49, 66 and 67. For reaction (b) see (1972FA07). See also ^{16}O in (1977AJ02), (1967SP09) and (1968DA1K, 1968ZE1B, 1969JO23, 1970JA1J; theor.).
See (1969HO13), ^{13}N in (1970AJ04, 1976AJ04) and ^{16}O in (1971AJ02, 1977AJ02).
At E_{α} = 42 MeV, angular distributions of ^{6}Li ions corresponding to transitions to ^{12}C*(0, 4.4) have been measured by (1964ZA1A). Reaction (b) at E_{α} = 22.9 MeV proceeds by sequential decay via states in ^{14}N, ^{16}O or ^{6}Li to ^{12}C_{g.s.} (1969BA17): see also ^{6}Li in (1974AJ01), ^{14}N in (1970AJ04) and ^{16}O in (1971AJ02).
See (1965SH1A) (reaction (a)) and (1973ST1A) (reaction (b)).
Angular distributions of α_{0} and α_{1} have been measured for E_{p} up to 18.6 MeV (see (1968AJ02)) and at six energies in the range E_{p} = 19.85 to 43.35 MeV (1971GU23). At E_{p} = 43.7 MeV the angular distributions to the 0^{+} states ^{12}C*(0, 7.66, 17.76) are fitted by L = 1, and L = 3 is consistent with the distributions to ^{12}C*(14.1, 16.1) [J^{π} = 4^{+} and 2^{+}, respectively] (1972MA21). The lifetime of ^{12}C*(4.4) τ_{m} = 65 ± 9 fsec (1970CO09). The energy of the second excited state of ^{12}C is 7654.2 ± 1.6 keV. The weighted average of this and previous values leads to E_{x} = 7654.6 ± 1.1 keV, a value which leads to a sharply reduced rate for the (ααα) process (1973MC01). See also (1972CA1N, 1973CL1E; astrophys. questions) and (1967SP09).
At E_{α} = 42 MeV angular distributions have been obtained for all four of the transitions ^{12}C_{g.s.} + ^{7}Li*(g.s., 0.48) and ^{12}C^{*}_{4.4} + ^{7}Li*(g.s., 0.48) (1968MI05).
There is evidence for the involvement of many ^{12}C states: see (1965RO05, 1967CA1C). See also (1973CL1E; astrophys. questions).
For reaction (a) see (1968AJ02). Reaction (b) appears to proceed primarily via excited states of ^{13}N and ^{16}O to ^{12}C*(0, 4.4): see (1971EP03: E_{p} = 46.8 MeV) and (1972BO71: E_{p} = 50 MeV), ^{13}N in (1976AJ04) and ^{16}O in (1971AJ02, 1977AJ02). At E_{p} = 160 MeV, unpublished measurements by S.L. Kannenberg quoted by (1971EP03) show that reaction (b) proceeds in part by quasielastic scattering to ^{12}C_{g.s.}. See also (1970GO12).
Angular distributions have been determined at E_{d} = 13.6 and 14.6 MeV (1974GA30: g.s.), 14.6 MeV (1964DA1B: g.s.), 19.5 MeV (1971GU07: g.s., 4.4), 28 MeV (1972BE29, 1972BE1T: g.s., 4.4), 35 MeV (1975BE01: g.s.) and 55 MeV (1971MC04: g.s., 4.4, 7.7, 9.6, 14.1). See also (1969KE1C, 1972CO23), (1967OG1A, 1972GA1E) and (1971DR02, 1972RO1L, 1974DO03, 1974KU05; theor.).
Angular distributions have been measured at E(^{3}He) = 25.5 to 29 MeV (1972PI1A: ^{12}C*(0, 4.4) + ^{7}Be*(0, 0.4)) and 30 MeV (1970DE12: ^{12}C*(0, 4.4, 9.6) + ^{7}Be*(0, 0.4), ^{12}C*(7.6) + ^{7}Be(0)). See also (1971DE37, 1973PI1B, 1973ST1N) and (1972RO1L, 1973KL1B; theor.). (1975AU01) report the extraction of the αparticle pickup spectroscopic factor S_{α} using a finite range DWBA analysis (E(^{3}He) = 26 MeV).
Reaction (a) at E_{α} = 25 MeV proceeds in part by sequential decay via states in ^{16}O and ^{20}Ne (1968PA12): see (1971AJ02, 1972AJ02). See also (1971BR1G, 1972SH1J). Angular distributions for the transitions to ^{12}C*(0, 4.4) in reaction (b) have been studied at E_{α} = 35.5 to 41.9 MeV (1965BR13) and 65 MeV (1973WO06). The excitation of ^{12}C*(9.6, 14.1) is also reported (1973WO06, 1974WO1D). See also (1972SH10; theor.) and (1973SC1B).
See (1966GA10). See also (1969BR1D) and (1970AN1D; theor.).
Angular distributions have been measured at E(^{16}O) = 23.9 MeV (1974SP06: g.s. + g.s.) and 51.5 MeV (1974RO04: ^{12}C*(0, 4.4) and various ^{20}Ne states). See also (1971SI1F, 1973PE1D, 1974ER1A), ^{20}Ne in (1978AJ03) and ^{32}S in (1973ENVA).
See (1967DE03).
The decay of the lowest T = 2 state of ^{16}O to ^{12}C*(0, 4.4) has been studied by (1973KO02). See also ^{16}O in (1977AJ02).
See (1963DE02; unpublished).
See (1969GO1B, 1971GO1R). See also ^{20}Ne in (1972AJ02).
Ground state angular distributions have been measured at E_{d} = 9 to 14.5 MeV (1964DA1B, 1967DE03, 1967DE14).
See (1967DE14).
See (1972SE1J).
See (1973GA14).
The αinduced fission of ^{20}Ne has been studied by (1962LA05, 1962LA03, 1962LA15, 1963LA08). See also (1974VO09, 1974WI05).
At E(^{16}O) = 42 MeV (1972MA36) and 56 MeV (1974GR1R) angular distributions involving ^{12}C*(4.4) and several ^{28}Si states have been measured.
