(See Energy Level Diagrams for 12C)
Cluster Model: (1983DZ1A, 1983JA09, 1984KR10, 1985DE05, 1985KO2B, 1985KW02, 1986GU1F, 1986KA51, 1986OR1C, 1986SA03, 1986SA1D, 1986SU12, 1986ZE1A, 1987JI01, 1987KU1B, 1987MI1L, 1987WA07, 1987ZE05, 1988FL1A, 1988HA39, 1988KA1Z, 1988MI26, 1988OS04, 1988OS1E, 1988RU1C, 1989KW1A, 1989OR05).
Special states: (1984BA38, 1984CA1N, 1984CO16, 1984CO21, 1984MO13, 1984SA31, 1984SA37, 1984TR1C, 1984ZW1A, 1985CA23, 1985CH27, 1985CO05, 1985GO1A, 1985HA1J, 1985KU22, 1985PA12, 1985RO1G, 1985SHZL, 1986AN10, 1986CH25, 1986DI04, 1986HU1E, 1986KA51, 1986KH1G, 1986OR1C, 1986PA06, 1986SA03, 1986SA32, 1986SU18, 1986VO07, 1987BL18, 1987BO1L, 1987CA1E, 1987JI01, 1987KA18, 1987KI1C, 1987MA08, 1987PR01, 1987PR03, 1987SC1J, 1988AJ1C, 1988AL1D, 1988BL10, 1988GU13, 1988KW02, 1988PO1C, 1988SP1A, 1989BA60, 1989KW1A, 1989OR02, 1989OR05, 1989RO03).
Electromagnetic transactions: (1984CI1B, 1984ER06, 1984LO05, 1984MO13, 1984VA06, 1985AR07, 1985CA23, 1985GR1A, 1986AN10, 1986CH25, 1986KE1P, 1986SA32, 1986VO07, 1987CA1E, 1987ER1F, 1987RA01, 1987ST1E, 1989BA60).
Astrophysical questions: (1982BA1D, 1982BU1A, 1982CA1A, 1982GR1A, 1982WO1A, 1984CO1H, 1984HA1R, 1984LA1J, 1984LI1L, 1984RA1E, 1984TR1C, 1984WE1C, 1985AR1A, 1985BR1E, 1985DW1A, 1985GU1A, 1985HA1R, 1985HE1F, 1985KH1D, 1985KO2A, 1985MI1E, 1985NO1B, 1985TA1A, 1985YO1A, 1986CH1H, 1986CO1R, 1986DO1L, 1986GO1Q, 1986KH1G, 1986LA16, 1986LA1C, 1986MA1E, 1986MA2E, 1986SM1A, 1986SN1C, 1986SN1D, 1986TH1E, 1986TR1C, 1986WI1L, 1986WO1A, 1987AL1B, 1987AR1C, 1987AU1A, 1987BE1H, 1987BO1B, 1987BR1P, 1987CU1A, 1987DO1A, 1987DW1A, 1987FU04, 1987HA1C, 1987HA1U, 1987HA1E, 1987KR1M, 1987LA1C, 1987MA2C, 1987ME1B, 1987MU1B, 1987PI1E, 1987PR1A, 1987RA1D, 1987RI1B, 1987SA1D, 1987SO1F, 1987WA1L, 1987WA1F, 1988AP1A, 1988AR1H, 1988AS1D, 1988BA86, 1988CA26, 1988CO1D, 1988CR1A, 1988CUZX, 1988DE1I, 1988DU1G, 1988FE1A, 1988FO1E, 1988JU1C, 1988KA1G, 1988MI1A, 1988PA1H, 1988RE1F, 1988SC1A, 1988TR1H, 1989BO1M, 1989CU1F, 1989DE1J, 1989GU1Q, 1989HA1O, 1989JI1A, 1989KA1K, 1989ME1C, 1989NO1A, 1989TH1C, 1989WE1G, 1989WY1A).
Applications: (1984CA1D, 1984HO1E, 1986BR1Q, 1986DR1E, 1986EN1A, 1986FR1H, 1986HE1F, 1986KI1J, 1986KO2E, 1986KR1F, 1986PE1F, 1986ST1K, 1986WE1E, 1987NA1D, 1987ST1C, 1988AL1K, 1988BU1C, 1988GO1M, 1988ILZZ, 1988MA1I, 1988PU1A, 1988RO1L, 1988SC1C, 1989BO1L).
Complex reactions involving 12C: (1983AG1A, 1983AL1G, 1983AL1H, 1983BO1D, 1983EL1A, 1984AB1C, 1984AI1B, 1984AN1G, 1984BA2F, 1984CH1L, 1984DE1Q, 1984FI17, 1984GA1G, 1984HO23, 1984KA1J, 1984KA1L, 1984KO1P, 1984MA1P, 1984NA12, 1985PA08, 1984ST1B, 1984XI1B, 1985AB1F, 1985AG1A, 1985BA1V, 1985FA02, 1985GA1H, 1985GH1A, 1985GU1A, 1985HA1N, 1985JA18, 1985KA1E, 1985KA1G, 1985KAZQ, 1985KI1E, 1985KW03, 1985LI1B, 1985MC03, 1985MO02, 1985MO08, 1985NE1G, 1985PO11, 1985PO14, 1985SI15, 1985SI19, 1985ST1B, 1985TA18, 1985UT01, 1985WA22, 1986AB06, 1986AL25, 1986AV1A, 1986BA1E, 1986BA1Q, 1986BE2M, 1986BO1R, 1986BO1B, 1986BU1K, 1986CH2G, 1986CS1A, 1986GH1A, 1986GR1L, 1986GR08, 1986GR1A, 1986GR1B, 1986GU1F, 1986HA1B, 1986KI1C, 1986MA19, 1986ME06, 1986MO15, 1986PL02, 1986PO06, 1986RA1L, 1986RE13, 1986SA30, 1986SH25, 1986SH1F, 1986SO10, 1986ST13, 1986UT01, 1986VA10, 1986VA18, 1986VA23, 1986WA1H, 1986WE1C, 1987AK1A, 1987AN1C, 1987AR19, 1987BA02, 1987BA1I, 1987BA31, 1987BA38, 1987BA1T, 1987BE58, 1987BE55, 1987BO23, 1987BO1K, 1987BU07, 1987CH1L, 1987DE37, 1987DO13, 1987FA09, 1987FE1A, 1987GE1A, 1987GH1A, 1987GO17, 1987GR1O, 1987JA06, 1987KI05, 1987KO15, 1987KW02, 1987LY04, 1987MU03, 1987MU1D, 1987NA01, 1987PA01, 1987PA1D, 1987PO23, 1987RI03, 1987RO10, 1987SH23, 1987SI10, 1987SN01, 1987SO15, 1987ST01, 1987TAZU, 1987VI02, 1987VI14, 1987YA16, 1987YI1A, 1988AV03, 1988AY03, 1988BA28, 1988BO1O, 1988BR1N, 1988CA06, 1988CA27, 1988CE01, 1988DE1J, 1988EL1D, 1988FE1A, 1988GA11, 1988GA12, 1988GA31, 1988GH1A, 1988GO1F, 1988GO11, 1988GU1K, 1988HA03, 1988KH1B, 1988KH1H, 1988KHZX, 1988KI06, 1988KW1C, 1988LI1H, 1988MI28, 1988MO1K, 1988MU1E, 1988PAZS, 1988POZZ, 1988PO1F, 1988PR1C, 1988RE13, 1988RU01, 1988SA19, 1988SH03, 1988SH1H, 1988SI01, 1988SM07, 1988TE03, 1988TS03, 1988TS01, 1988UC01, 1988UT02, 1989BL1D, 1989BR35, 1989CEZZ, 1989CH28, 1989CI1C, 1989FI05, 1989GH1B, 1989GU1C, 1989HA43, 1989HA08, 1989PA06, 1989PO06, 1989SA10, 1989SE03, 1989SU05, 1989TU1A, 1989YO02).
Muon and neutrino capture and reactions: (1983GM1A, 1984KU20, 1984KU11, 1984MI11, 1984RU12, 1985AG1C, 1985AR1B, 1985BO1U, 1985GR1A, 1985KI01, 1985MAZZ, 1985PA05, 1985PA12, 1986DA1J, 1986DO06, 1986DU06, 1986FI1G, 1986KE1Q, 1986KU05, 1986LI13, 1986MA16, 1986PA06, 1987BR1L, 1987FU13, 1987HA1Q, 1987KO1P, 1987KR1L, 1987MI17, 1987SU06, 1987VA1P, 1988AL1O, 1988BO1X, 1988BR24, 1988DO05, 1988FU08, 1988MI11, 1988MI20, 1989AR1I, 1989DR1A, 1989GM1A, 1989KR1C, 1989MI1I, 1989NA01).
Pion capture and reactions (See also reactions 28 and 34): (1981HO14, 1983AB1B, 1983AB1C, 1983AG1B, 1983AK1A, 1983BU1D, 1983GM1A, 1983KO1M, 1983MA16, 1984AL1K, 1984AL1L, 1984AS05, 1984BA1L, 1984BA2L, 1984BA1M, 1984BE28, 1984BE1Q, 1984BE1R, 1984BO1L, 1984BO1H, 1984BU11, 1984CE1D, 1984CH26, 1984CO16, 1984CO1D, 1984ER06, 1984GE1A, 1984GI1D, 1984GM01, 1984GR27, 1984JI03, 1984KA31, 1984KO1P, 1984LE11, 1984LI03, 1984MA1T, 1984MA1G, 1984MA1U, 1984MI11, 1984OH04, 1984RI12, 1984RO1D, 1984SA1H, 1984SC1B, 1984TO1A, 1984ZI1B, 1985AB1E, 1985ALZX, 1985AM1B, 1985AR15, 1985AS02, 1985AZ1A, 1985AZ1B, 1985BA2F, 1985BA1V, 1985BE1C, 1985BI01, 1985BI04, 1985BU1G, 1985CO11, 1985CO16, 1985DI02, 1985FU06, 1985FU14, 1985GI05, 1985GR1E, 1985GU13, 1985KA22, 1985KO06, 1985KO2C, 1985LA20, 1985LE1E, 1985LI1E, 1985MA1G, 1985MA1K, 1985ME1M, 1985MI04, 1985MI1L, 1985MO1H, 1985MO1M, 1985OH09, 1985RI04, 1985RO17, 1985RO1M, 1985SA06, 1985SE21, 1985SM06, 1985TA17, 1985TA24, 1985TO15, 1985TO14, 1985VA17, 1986AB1J, 1986AG1C, 1986ALZL, 1986AN40, 1986AR1F, 1986AS1A, 1986BA3E, 1986BA81, 1986BA3H, 1986BE22, 1986BE2L, 1986BL05, 1986BO03, 1986BO1N, 1986CH39, 1986CH1Z, 1986CH1J, 1986CO1V, 1986CZ01, 1986DI07, 1986DU1M, 1986ER1A, 1986FA03, 1986FO03, 1986GA33, 1986GA14, 1986GH1A, 1986GI13, 1986GR1K, 1986HA34, 1986HA26, 1986IV1A, 1986KA1J, 1986KH03, 1986KI1D, 1986LAZL, 1986MC04, 1986MI25, 1986MO1M, 1986MO1J, 1986MO26, 1986NA03, 1986OS01, 1986OS1H, 1986OS03, 1986PE1L, 1986PE05, 1986PR1C, 1986PR01, 1986RA1J, 1986RO03, 1986SU18, 1986TA1T, 1986VO17, 1986VO1H, 1986WA26, 1986WH02, 1986YO05, 1986ZO1A, 1987AB12, 1987AB1E, 1987AG1C, 1987AL1I, 1987AL26, 1987AN14, 1987AP1A, 1987AR1P, 1987AS1E, 1987BA2Q, 1987BE2A, 1987BE2B, 1987BL07, 1987BO1D, 1987BO1E, 1987BO1X, 1987BU20, 1987CH21, 1987CH1N, 1987CH24, 1987CH29, 1987CL02, 1987CO20, 1987EJ02, 1987FA05, 1987GA08, 1987GA11, 1987GI01, 1987GI1B, 1987GI1C, 1987GM02, 1987GM04, 1987GU07, 1987GU1I, 1987HA40, 1987HE04, 1987HO08, 1987HU13, 1987JO1B, 1987KA39, 1987KH1B, 1987KO30, 1987LE1B, 1987LO1F, 1987MA1I, 1987MA1Z, 1987MO1M, 1987NA04, 1987PI1B, 1987RA1H, 1987ST1E, 1987WE1A, 1987WU1B, 1988AB05, 1988AB1G, 1988AM04, 1988BA2G, 1988BE1V, 1988BE2D, 1988BE2F, 1988BU16, 1988CH49, 1988CH24, 1988CH31, 1988CU1C, 1988DH1A, 1988ER04, 1988ER1B, 1988FR02, 1988FR1D, 1988FR10, 1988FR1J, 1988GIZU, 1988GO13, 1988GO08, 1988GO14, 1988GR1E, 1988HA07, 1988HA12, 1988EL06, 1988IT02, 1988JO1E, 1988KH01, 1988KIZW, 1988KY1A, 1988LE1G, 1988MA27, 1988MA37, 1988MO23, 1988OH04, 1988OS1A, 1988PE1F, 1988PO1H, 1988RA1H, 1988RO1M, 1988SA24, 1988SA31, 1988WI1B, 1988WI1I, 1988YOZZ, 1989AR1K, 1989BA06, 1989BA1R, 1989BRZX, 1989EJ1A, 1989EN1B, 1989GH1B, 1989GO09, 1989GR06, 1989HA07, 1989KH01, 1989MO1D, 1989NA01).
Kaons and other mesons-capture and reactions (see also 19reaction 35): (1983AK1A, 1983AR1F, 1983GE1C, 1983TO21, 1984AB04, 1984AL1H, 1984BA2L, 1984BA1M, 1984BO1H, 1984CO21, 1984GI1E, 1984IW1B, 1984MA1G, 1984SI13, 1984TO1B, 1984YA04, 1984ZO02, 1985AB1E, 1985BE31, 1985BE62, 1985CO1H, 1985CO14, 1985CO05, 1985DA1D, 1985DI06, 1985DO1G, 1985GA1E, 1985GA1C, 1985GR10, 1985IA01, 1985MI04, 1985SH1H, 1985SI09, 1985WA1N, 1985YA01, 1985YA07, 1985ZH13, 1985ZH11, 1986AB07, 1986AG1B, 1986BA3L, 1986BA81, 1986BE1P, 1986BE2J, 1986BE42, 1986BI1G, 1986CH1P, 1986CH1I, 1986CO1U, 1986DA1G, 1986DA1B, 1986DO1B, 1986FI1A, 1986GA33, 1986GA14, 1986GA1H, 1986HA1Y, 1986HA34, 1986HA26, 1986HA39, 1986HU1B, 1986KA1J, 1986KI1K, 1986KI1D, 1986KO2D, 1986MA1J, 1986MI1N, 1986MO1J, 1986PE1L, 1986TA11, 1986YA1T, 1986ZH1E, 1986ZO1A, 1987AP1A, 1987BEYQ, 1987BE14, 1987BE1S, 1987BL1L, 1987CH10, 1987EJ02, 1987FA1A, 1987HA40, 1987KO30, 1987LE1B, 1987PI1B, 1987PO1H, 1987SM1A, 1987WU1B, 1987WU05, 1988BA1F, 1988BR16, 1988CH49, 1988FA1B, 1988GA1A, 1988HA07, 1988HA41, 1988HA44, 1988KO36, 1988MA09, 1988MO1B, 1988MO14, 1988MO23, 1988PA1B, 1988PE1F, 1988PO1H, 1988RO11, 1988TA29, 1988TA14, 1988WA1B, 1988YA05, 1989BA06, 1989EJ1A, 1989HA07).
Hypernuclei: (1983SH1E, 1984AL1H, 1984AS1D, 1984BA1M, 1984BA1N, 1984BO1H, 1984MA1G, 1984MA1U, 1984MI1E, 1984SA1J, 1984ZO02, 1985AH1A, 1985GA1E, 1985GR10, 1985MI04, 1985OS1C, 1985WA1N, 1986BA3L, 1986BA1H, 1986AB81, 1986BI1G, 1986CO1U, 1986DA1G, 1986DA1B, 1986DO1B, 1986DU1M, 1986DU1P, 1986ER1A, 1986FE1A, 1986FR1J, 1986GA33, 1986GA14, 1986GA1H, 1986HA1Y, 1986HA34, 1986HA39, 1986HE01, 1986HU1B, 1986KO1A, 1986MI1N, 1986OS1G, 1986PE1L, 1986PO1H, 1986SZ1A, 1986YA1T, 1986ZO1A, 1987BA2K, 1987DA1F, 1987DA30, 1987DO1B, 1987EJ02, 1987MA08, 1987MA2A, 1987MI38, 1987PI1C, 1987PO1H, 1987RU1A, 1988BA1F, 1988BA1G, 1988BA82, 1988BO1P, 1988CH48, 1988DL1A, 1988GA1A, 1988GA1I, 1988GR1B, 1988HA07, 1988HA44, 1988MA09, 1988MA1G, 1988MO1B, 1988MO14, 1988MO23, 1988MO1L, 1988PE1F, 1988PO1H, 1988TA29, 1988WA1B, 1989BA06, 1989EJ1A, 1989KI25, 1989MR01).
Antinucleon interactions (see also reaction 38): (1984BA39, 1984CL1C, 1984DA1J, 1984DA23, 1984DO1E, 1984GA26, 1984KR22, 1984RI1D, 1984SA1M, 1984SU07, 1984VO1D, 1985AB1E, 1985BA09, 1985BA51, 1985CA16, 1985DA1D, 1985DA06, 1985DA24, 1985DA1G, 1985DO1E, 1985DU05, 1985HE24, 1985KU04, 1985KU08, 1985LI1J, 1985NA14, 1985PI14, 1985SU11, 1985VO06, 1986AU1D, 1986BA22, 1986BO26, 1986BU1J, 1986DI04, 1986DO20, 1986DU10, 1986FR10, 1986HE05, 1986IN01, 1986JA04, 1986MA46, 1986MC04, 1986MO1J, 1986SP01, 1986ZA06, 1987BA21, 1987BE26, 1987DA12, 1987DA1D, 1987GR1I, 1987HE04, 1987IS03, 1987MA04, 1987MA46, 1987SM1A, 1987VO1B, 1987YA1E, 1987ZA08, 1988DA07, 1988DE40, 1988GO13, 1988LI1O, 1988OK03, 1989AR1K, 1989CH13, 1989MA24, 1989MU1D).
Other topics: (1984CH1L, 1984CL11, 1984CO16, 1984GR18, 1984JE02, 1984LO05, 1984SH1X, 1985AN28, 1985AR07, 1985AR1B, 1985BU1F, 1985CI04, 1985KE1G, 1985KU22, 1985PA1M, 1985SHZL, 1985TH1D, 1986AL1T, 1986BE23, 1986BE39, 1986BI01, 1986DU06, 1986FO03, 1986KU11, 1986KE1P, 1986KU1B, 1986KU1P, 1986SA02, 1986SH2E, 1986WE1G, 1986YA1F, 1987AB21, 1987FUZZ, 1987HO07, 1987KU1I, 1987MO14, 1987PR01, 1987ZE05, 1988BO04, 1988FL1A, 1988HA38, 1988JA13, 1988KW02, 1988MO1H, 1988OH01, 1988OR1C, 1988OS1E, 1988RO18, 1988RU1B, 1989BA60, 1989CE01, 1989FI04, 1989JI04, 1989OR02, 1989RE1C, 1989RO01).
Ground-state properties of 12C: (1984AN1B, 1984BA2F, 1984BR25, 1984LO05, 1984RU12, 1985AN16, 1985AN28, 1985BE59, 1985CL1A, 1985GO1A, 1985KO02, 1985MI23, 1985OR01, 1985SA32, 1985SA30, 1985SH1A, 1985TA18, 1986AL1T, 1986AN35, 1986EL1A, 1986HE26, 1986KA2C, 1986KU1B, 1986LE16, 1986NI01, 1986RO03, 1986SA32, 1986SY1A, 1986WI04, 1987AB03, 1987AL05, 1987BL18, 1987BO42, 1987ER1F, 1987FU1D, 1987GI1C, 1987GU1C, 1987HA30, 1987JI01, 1987KI1C, 1987PR03, 1987RA01, 1987SA15, 1987ZE05, 1988BI1A, 1988CU1C, 1988DA1J, 1988DZ1A, 1988GU03, 1988HA38, 1988JO1C, 1988ME09, 1988OH01, 1988RA1G, 1988SP1A, 1988TA10, 1988VA03, 1988WO04, 1989BE03, 1989OR05, 1989RO01).
Isotopic abundance: (98.90 ± 0.03)% (1984DE53).
12C*(4.44): Q = 6 ± 3 e · fm2, indicating a substantial oblate deformation (1983VE01).
The excitation functions for some final states in 11B and 11C (reactions (a) and (b)) are structureless while others (to states with Jπ = 3/2-, 5/2-, 5/2+) exhibit pronounced structures. The most prominent of these is observed at E(6Li) = 8.4 MeV [12C*(32.4)] in the p2 and n2 yields with a width Γc.m. ≈ 1 MeV (1987DO05). Reaction (d) has been studied for E(6Li) = 2.4 to 6.7 MeV in a kinematically complete experiment (1988LA11). See also (1984LA19, 1987LA25). For reactions (e) and (f) see (1983WA09). Broad structures have been observed in the elastic scattering at E(6Li) ≈ 13 and 26 MeV: see (19880AJ01). See also (1985AJ01), 6Li and 8Be in (1988AJ01), 11B and 11C here, (1985NO1A), (1988WE20) and (1988MC1E; applied).
Observed resonances are displayed in 12.8 (in PDF or PS). 12C*(28.2) appears to be formed by s- and d-wave capture. The γ0 and γ2 transitions to the 0+ states 12C*(0, 7.7) are strong and show a similar energy dependence. A strong non-resonant contribution is necessary to account for the γ1 yield. The resonance structure appears to confirm the role of 3p3h configurations for 12C excitations somewhat above the giant resonance region. The γ3 yield is relatively unstructured: see (1980AJ01). See also (1984MAZP, 1985BL1B).
Excitation functions for neutrons, production cross sections for 11C and polarizations have been measured for E(3He) = 1.2 to 10 MeV for several neutron groups. No sharp structure is observed but there is some suggestions from angular distribution data and excitation functions at forward angles for a structure (Γ ≈ 350 keV) at E(3He) ≈ 2 MeV: Ex = 27.8 MeV. The total cross section for 11C production shows a broad maximum, σ = 113 mb at E(3He) = 4.3 MeV. In the range E(3He) = 5.7 to 40.7 MeV it decreases monotonically. Excitation functions and angular distributions for protons (reaction (b)) have been measured for E(3He) = 1.0 to 10.2 MeV for a number of proton groups. No pronounced structures are reported. See also (1986SL1B; theor.).
Analyzing powers have been measured at E(pol. 3He) = 33.3 MeV for nine deuteron groups (reaction (c)). The cross section for ground-state tritons (reaction (d)) increases monotonically for E(3He) = 2.5 to 4.2 MeV and then shows a broad maximum at E(3He) ≈ 4.5 MeV.
The elastic scattering excitation function (reaction (e)) decreases monotonically for E(3He) = 4.0 to 9.0 MeV and 15.0 to 21.0 MeV. At θc.m. = 111° a slight rise is observed for E(3He) = 19 to 21 MeV. Polarization measurements have been reported at E(3He) = 18, 31.4 and 32.8 MeV.
Excitation functions for the α0 group (reaction (f)) have been reported for E(3He) = 2 to 10 MeV. Analyzing powers have been measured at E(pol. 3He) = 33.3 MeV. For reaction (g) see (1986LA26, 1987WA25).
Neutron groups have been observed to 12C*(0, 4.4, 7.7, 9.6, (10.1), (10.8)). Angular distributions have been measured at many energies in the range Eα = 1.75 to 23 MeV [see (1968AJ02, 1975AJ02)] and at 28 and 32 MeV (1985GUZQ; prelim.; n0→3). [The work at Eα = 35 MeV reported in (1985AJ01) has not been published: see, however, Fig. 1 in (1986AS02).] See also (1985CA41, 1988CA26; astrophysics) and (1986PH1C, 1987TC1A; applications).
At E(6Li) = 32 MeV angular distributions have been studied to 12C*(0, 4.4, 7.7, 9.6, 10.8, 11.8, 12.7, 14.1). There is no indication of the T = 1 states. 12C*(9.64) is relatively strongly populated (1986AS02; FRDWBA). See also (1980AJ01).
At E(3He) = 13 MeV neutron groups are observed to 12C*(0, 4.4, 7.7, 16.1, 17.8) and to excited states at Ex = 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 12C (1974GO23).
The (d, γγ) excitation functions [via the Jπ = 1+, T = 1 state at Ex = 15.1 MeV] has been measured for Ed = 2.655 to 2.91 MeV. The non-resonant yield of 15 MeV γ-rays is due to a direct capture process or to a very broad resonance: see (1975AJ02).
The thin-target excitation function in the forward direction (reaction (a)) in the range Ed = 0.3 to 4.6 MeV shows some indication of a broad resonance near Ed = 0.9 MeV. Above Ed = 2.4 MeV, the cross section increases rapidly to 210 mb/sr at 3.8 MeV, and then remains constant to 4.6 MeV. Excitation functions have also been measured for Ed = 3.2 to 16.0 MeV. Thick target yields for 4.3 MeV γ-rays for Ed = 111 to 170 keV have also been studied and astrophysical S-factors have been calculated. In reaction (b) yields of protons have been measured for Ed = 91 keV to 12 MeV: no clear resonance structure is observed.
The yield of elastically scattered deuterons has been measured for Ed = 1.0 to 2.0 MeV (there is some suggestion of resonances) and for Ed = 14.0 to 15.5 MeV. Excitation functions for the deuterons to 10B*(1.74, 2.15) [Jπ; T = 0+; 1 and 1+; 0, respectively] have been measured at several angles for Ed = 4.2 to 16 MeV: they are characterized by rather broad, slowly varying structure: see (1980AJ01) [see also for polarization measurements]. See also 10B in (1988AJ01).
Excitation functions have been measured for the α0 and α1 groups for Ed = 0.4 to 12 MeV. Broad maxima in the α0 yield are reported at Ed ≈ 1 (Γ ≈ 0.5), 2 and 4.5 MeV (Γ ≳ 1 MeV) as well as, possibly, at 6 MeV. Involvement of the isoscalar giant quadrupole resonance [Ex ≈ 28 MeV, Γ ≈ 4 MeV] is suggested: see (1980AJ01). See also 8Be in (1988AJ01) and (1988KA1M; theor.).
Angular distributions have been measured at Eα = 15.1 to 25.2 MeV [see (1980AJ01)], 29.5 MeV (1983VA28; d0, d1) and 31.2 MeV (1984KO1Q; d0, d1). For dγ4.4 angular correlation studies see (1987VA04, 1988IG04, 1988VA1D). See also (1984BE23; theor.).
At E(6Li) = 4.9 MeV angular distributions have been obtained for the α-particles to 12C*(0, 4.4, 7.7, 9.6). The population of 12C*(11.8, 12.7) is also reported, as is that of 12C*(15.11) [T = 1]: see (1975AJ02).
In view of the complexity of the availiable information on these three reactions, we will first summarize the experimental results and then review the evidence for the parameters of 12C states observed as resonances: see 12.11 (in PDF or PS). See (1975AJ02, 1980AJ01) for references.
(a) In the range 4 < Ep < 14.5 MeV σ(γ0) is dominated by the great dipole resonance at Ep = 7.2 MeV (Ex = 22.6 MeV, Γc.m. = 3.2 MeV), while the giant resonance in γ1 occurs at Ep ≈ 10.3 MeV (Ex = 25.4 MeV, Γc.m. ≈ 6.5 MeV). Absolute cross section measurements from Ep = 5 to 14 MeV suggest that dσ/dΩ (90°)L = 13.1 ± 1.3 μb/sr be used as a standard at the Ep = 7.25 MeV peak of the GDR.
A study of the giant dipole resonance region with polarized protons (Ep = 6 to 14 MeV) sets new limits on the configuration mixing in the γ0 giant resonance. The analysis of γ1 is more complicated: the asymmetry results are consistent either with a single Jπ = 2- state or with interference of pairs of states such as (1-, 3-), (2-, 3-) and (1-, 2-). The 90° yield of γ0, γ1, γ2 and γ3 [to 12C*(0, 4.4, 7.7, 9.6)] has been studied by (1977SN01): the γ2 yield shows a peak at Ep ≈ 14.3 MeV with a cross section ≈ 2.3% that of γ0 [in γ0 yield, Eres = 15.0 MeV (1977SN01)] and perhaps as well a low intensity structure at Ep = 11.8 MeV. The γ3 yield exhibits two asymmetric peaks at Ep = 12.5 and 13.8 MeV (Γ ≈ 0.7 and 2.5 MeV) and a weaker structure at ≈ 9.8 MeV (1977SN01).
At Epol. p = 50 MeV, angular distributions and analyzing power measurements are reported to 12C*(0, 4.4, 9.6, 18.8 ± 0.5 [u], 22.3 ± 1.0 [u]) by (1985NO01) [u = unresolved]. Measurements are also reported at Epol. p = 28.5 MeV (1984BL10) and 40 to 80 MeV (1986EJ1A, 1986SH1Y; prelim., γ0, γ1). (1988HA04) have studied the γ0 group for Epol. p = 20 to 100 MeV. See also (1985HA05). In earlier work (1982WE08) studied the γ0 and γ1 yields for Ep = 8 to 60 MeV and the γ19 yield for Ep = 23 to 60 MeV. Giant resonances based on various states of 12C have been reported at Ex = 22.5 and 25.5 MeV [γ0], 25.5, 27.4 and (31) MeV [γ1], 27.4, 31 and (37) MeV [γ3], as well as in the γ-yield to higher states: see (1985AJ01). The γ19 yield shows a structure at Ep ≈ 43 MeV (1983AN16; Ep = 18 to 45 MeV; also γ to 12C*(0, 4.4, 9.6, 12.7 [u], 15.5 [u]).
(c) This reaction has been studied at energies to 20 MeV. The cross sections for the reactions vie 8Beg.s. and 8Be*(2.9) [α0, α1] have been determined for Ec.m. = 22 to 1100 keV. The total cross section shows the 162 keV resonance and a broad peak centered at 600 keV. At Ec.m. = 300 keV σ(α0) = 1.03 ± 0.06 mb and σ(α1) = 165 ± 10 mb (1987BE17). The parameters of the 162 keV resonance are Eres(c.m.) = 148.3 ± 0.1 keV, Γc.m. = 5.3 ± 0.2 keV (1987BE17), 149.8 ± 0.2 keV, 5.2+0.5-0.3 keV (1979DA03). Derived S-values lead to S(0) = 197 ± 12 MeV · b (1987BE17). This reaction is of possible interest for fusion reactors.
See also 8Be in (1988AJ01), (1985NO1G, 1986KU18), (1984BR1L, 1984SN01, 1985DO1F, 1986SN1B, 1986WE1D, 1988HA1W), (1983SG1B, 1984HA1J, 1986KA1U, 1986PR1D, 1986ZI01, 1988KI1C; applications), (1983HA1B, 1984YA1A, 1985CA41, 1987AS05, 1988CA26; astrophysics) and (1984CA18, 1984SE16, 1985GO1B, 1985KI16, 1985RA10, 1987AS05, 1987KI1C, 1987KO1X; theor.).
The parameters of the observed resonances are displayed in 12.11 (in PDF or PS). The following summarizes the information on the low-lying resonances: for a full list of references see (1968AJ02, 1980AJ01, 1985AJ01).
Ep= 0.16 MeV [12C*(16.11)]. This is the Jπ = 2+; T = 1 analog of the first excited states of 12B and 12N. The γ-decay is to 12C*(0, 4.4, 9.6), and also 12C*(12.71) [see 12.7 (in PDF or PS)]: the angular distribution of γ3, together with the known α-decay of 12C*(9.6), fix Jπ = 3- for the latter.
Ep= 0.67 MeV [12C*(16.57)]. The proton width [Γp ≈ 150 keV] indicates s-wave protons and therefore Jπ = 1- or 2-. This is supported by the near isotropy of the two resonant exit channels, α1 and γ1. The α1 cross section indicates 2J + 1 ≥ 5: therefore Jπ = 2-. [This is consistent with the results of an αα-correlation study via 8Be*(2.9)]. The γ1 E1 transition has |M|2 ≈ 0.1 W.u., suggesting T = 1.
Ep= 1.4 MeV [12C*(17.23)]. (2J + 1)Γγ0 ≥ 115 eV. This indicates Jπ = 1-, with T = 1 most probable. Jπ = 1- is also required to account for the interference at lower energies in α0 and γ0 and is consistent with the αα-correlation results. Two solutions for Γp are possible; the larger (chosen for 12.11 (in PDF or PS)) is favored by elastic scattering data.
Ep= 2.0 MeV [12C*(17.8)]. The resonance in the yield of α0 requires natural parity, the small α-widths suggest T = 1. For Jπ = 1- or 3- the small γ-widths would be surprising; Jπ = 2+ would lead to a larger anomaly than is observed. Jπ is then 0+, T = 1. (1982HA12) [Ep = 0.82 to 2.83 MeV] report Ex = 17.80 MeV [Γc.m. = 96 ± 5 keV] decays via a 5.10 ± 0.03 MeV γ-ray to 12C*(12.71): Γγ = 3.7 ± 1.5 eV. The angular distribution is isotropic, as expected.
Ep= 2.37 MeV [12C*(18.13)]. Seen as a resonance in the yield of 15.1 MeV γ-rays: σR = 0.77 ± 0.15 μb, Γc.m. = 600 ± 100 keV, (2J + 1) Γγ ≥ 2.8 ± 0.6 eV. The results are consistent with Jπ = 1+, T = 0, but interference with a non-resonant background excludes a definite assignment.
Ep= 2.62 MeV [12C*(18.38)]. The resonance for α0 requires natural parity; the presence of a large P4 term in the angular distribution requires J ≥ 2 and lp ≥ 2. (1982HA12) report Ex = 18.38 MeV, Γc.m. ≈ 400 keV, Γγ (to 12C*(9.6)) = 5.7 ± 2.3 eV, consistent with Jπ = 3-; T = 1. The total peak cross section is 4.2 ± 1.7 μb. Transitions to 12C*(0, 4.4) are also observed: Γγ ≈ 2 × 10-3 eV and 3.2 ± 1.0 eV, respectively.
Ep= 2.66 MeV [12C*(18.39)] is not seen here: see 11B(p, p).
Ep= 3.12 MeV [12C*(18.81)]. The angular distribution of γ0 indicates E2 radiation, Jπ = 2+. This assignment is supported by the angular correlation in the cascade γ1 and by the behavior of σ(α0); T = 1 is suggested by the small Γα. The yield of γ3 (to 12C*(9.6)) shows a peak corresponding to Ex ≈ 18.9 - 19.0 MeV. It may be due to 12C*(18.8) with an energy shift due to interference.
The structure near Ep = 3.5 - 3.7 MeV [12C*(19.2, 19.4)] seems to require at least two levels. The large Γγ0 requires that one be Jπ = 1-, T = 1 and interference terms in σ(α0) require another to have even spin and even parity: Jπ = 2+, T = 0 is favored. (1982WR01) report that they do not observe any evidence for an isospin mixed doublet near Ex = 19.5 MeV [Ep = 2.9 to 4.6 MeV (60° and 90°)]. Resonances at Ep = 4.93 and 5.11 MeV, seen in σ(γ1) also appear in σ(α1), but not in σ(α0). Angular distributions suggest Jπ = 2+ or 3- for the latter [12C*(20.64)]; the strength of γ1 and absence of γ0 favors Jπ = 3-, T = 1.
The first seven T = 1 states in 12B and 12C have been identified by comparing reduced proton widths obtained for this reaction and reduced widths obtained from the (d, p) and (d, n) reactions: see 12.12 (in PDF or PS) in (1980AJ01).
Excitation functions have been studied from threshold to 27.5 MeV [see (1980AJ01, 1985AJ01)] and at Ep = 13.7 to 14.7 MeV (1985SC08; n0 → n3, n4+5, n6, n7) and 16 to 26 MeV (1985GR09; n0 → n3). See also (1986AI04). At the lower energies many resonances are observed: see 12.12 (in PDF or PS).
Polarization measurements have been carried out for Epol. p = 7.0 to 26.5 MeV [see (1980AJ01, 1985AJ01)]. For high-energy interactions see (1984BA1R, 1984BA1U). See also 11C, (1989RA09), (1985CA41; astrophysics) and (1985RA10; theor.).
Anomalies and maxima observed in the excitation functions of p0 → p3 are displayed in 12.12 (in PDF or PS). Studies of the scattering have been reported at Ep = 1.8 to 47.4 MeV [see (1980AJ01, 1985AJ01)] and at Ec.m. ≈ 0.15 to 1.1 MeV (1987BE17; p0). A study of the yield of γ-rays is reported to lead to 12C*(18.98, 19.93, 20.63) (1988ABZW; prelim.). A review of the evidence on the states with 20.2 < Ex < 22.5 MeV suggests that in all the channels and throughout this energy range a strong 2+ background is observed, which may be the low-energy tail of the isoscalar giant quadrupole resonance (1983BO19). For polarization measurements [Ep = 1.9 to 155 MeV] see (1975AJ02, 1980AJ01, 1985AJ01). For reaction (b) see (1985AJ01) and 10B in (1988AJ01). For studies of high-energy interactions see (1984BA1U, 1984BA1T). See also (1985MUZZ), (1986BA88) and (1985RA10, 1987RA14; theor.).
Reported neutron groups are displayed in 12.13 (in PDF or PS). Angular distributions have been studied for Ed = 0.5 to 12 MeV [see (1968AJ02, 1975AJ02, 1985AJ01)] and at Epol. d = 79 MeV (1985FO05, 1987FO22); to 12C*(0, 4.4, 9.6, 12.7, 15.1; DWBA-EFR). For polarization measurements see (1987FO22, 1986FO08) and 13C in (1991AJ01). For angular correlation studies see (1980AJ01) and (1985NE01) [ 12.13 (in PDF or PS)].
Observed deuteron groups are displayed in 12.13 (in PDF or PS). Angular distributions have been studied at E(3He) = 5.1 to 44 MeV [see (1975AJ02, 1980AJ01)] and at 18.3 and 22.3 MeV (1988IG03; d0, d1; also d1γ angular correlations). See also (1987BA2B, 1987ZE02; theor.).
Angular distributions have been studied in the range Eα = 15.1 to 120 MeV [see (1980AJ01, 1985AJ01)] and at Eα = 30.1 (1983VA28; t0, t1, t2) and 31.2 MeV (1984KO1Q; t0, t1). Angular correlation measurements (t1, γ) are reported at Eα = 21 to 30 MeV: see (1987VA04, 1988IG04, 1988VA1D). See also (1987LE33) and (1984BE23, 1985ZE04, 1987BA2B, 1987ZE02, 1989BA90; theor.).
At E(7Li) = 34 MeV, angular distributions have been measured for the groups to 12C*(0, 4.4, 7.7, 9.6, 10.8, 11.8, 12.7, 15.1, 16.1, 18.35) (1983NE11). It is concluded on the basis of this and other work, that the group corresponding to Ex = 18.35 ± 0.05 MeV (Γ = 350 ± 50 keV) consists of unresolved states with Jπ = 3- (T = 1) and 2- (T = 0 plus some mixing of T = 1) (1983NE11; see for spectroscopic factors): no states were observed with Ex > 18.35 MeV. See also (1987CO16, 1988BEYJ).
Angular distributions involving 12C*(0, 4.4) and 10Be*(0, 3.4) have been measured at E(11B) = 11 MeV (1985PO02).
The decay is mainly to 12Cg.s.; branching ratios to 12C*(0, 4.4, 7.7, 10.3) are displayed in 12.14 (in PDF or PS). All the observed transitions are allowed. The half-life is 20.20 ± 0.02 ms (1978AL01).
12C*(7.7) [Jπ = 0+] is of particular interest for helium burning processes in stars: Γrad = 3.41 ± 1.12 meV. A search for transitions to 12C*(12.7) has been unsuccessful: see (1968AJ02, 1975AJ02). The shapes of the β-spectra of 12B and 12N have been analyzed.
The total absorption, mainly (γ, n) + (γ, p), is dominated by the giant resonance peak at 23.2 MeV, Γ = 3.2 MeV [σmax = 21 mb] and by a smaller structure at 25.6 MeV, Γ ≈ 2 MeV [σmax ≈ 13 mb]: see (1968AJ02, 1975AJ02, 1980AJ01) for a detailed listing of the earlier references and results. See also (1984GH1A, 1985GH1B).
The (γ, n) cross section shows a giant resonance, σmax ≈ 7 - 8 mb, centered at about 23 MeV and consisting of an ≈ 1 MeV-wide group at 22.3 MeV and an ≈ 2 MeV-wide group at ≈ 23.3 MeV. A secondary maximum occurs at 25.5 MeV, Γ ≈ 2 MeV. There is also evidence of other structure at ≈ 30 - 31 and possibly at ≈ 35 MeV: see (1988DI02) and B.L. Berman, private communication.
The (γ, n0) cross section has been measured at 90° for 21 < Ex < 40 MeV and compared with the (γ, p0) cross section: the isospin mixing averages about 2% in intensity and shows structure at the giant resonance. Angular distributions of n0 measured over the giant resonance region indicate that the main excitation mechanism is of a 1p3/2 → d5/2 E1 single-particle character. No significant E2 strength is observed: see (1980AJ01). Differential cross sections at θlab = 65° have been measured for the n0+1 and n2→9 groups for Eγ = 33.7 to 99.4 MeV (1988HA01). See also the discussion in (1985FU1C).
The (γ, 2n) cross section (reaction (b)) 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 Eγ = 20 to 140 MeV: see (1980AJ01, 1985AJ01). See also (1985AH06, 1985GI1G, 1985HO27, 1985PY01), (1989BO1F; astrophysics) and (1984CA18, 1984MO13, 1984VA1G, 1985BO12, 1985GO1A, 1985KO2K, 1985VA1C, 1986VA14, 1987BR21, 1987FE05, 1987GO37, 1987KI1C, 1987VA35, 1988CO1G; theor.).
The photoproton cross section exhibits two broad peaks, the giant resonance peak at 22.5 MeV, Γ = 3.2 MeV, σmax = 13.1 ± 0.8 mb and a 2 MeV broad peak at 25.2 MeV, σmax = 5.6 ± 0.3 mb: see (1976CA21) and 12.19 (in PDF or PS) in (1968AJ02). The (γ, p0) cross section at the giant resonance is 11.0 ± 1.1 mb (1986KE06). While the E1 component dominates in the GDR, a 2% E2 contribution may possibly be present (1976CA21). In contrast with the giant resonance peak in the (γ, n) cross section, the (γ, p) cross section shows a strong 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: see (1985FU1C). There is agreement between the (γ, p) results and those from the inverse reaction 11B(p, γ0) [see reaction 17] when the population of 11B*(4.4, 5.0) is taken into account. See also 11B and (1986AN25, 1986MC15, 1988SH08). At Eγ = 28 MeV the branching ratios to 11B*(0, 2.12, 4.4 + 5.0) are, respectively, (76 ± 4)%, (13 ± 1.3)% and (11 ± 1.2)% (1989FE01). See also reaction 30. For the proton momentum spectrum at Eγ = 357 ± 10 MeV see (1984HO24). For the cross section with polarized photons with Eγ = 41.2 to 93.0 MeV see (1988YO1A). For measurements in the Δ-resonance region see (1987KA13).
The photoproduction of neutral pions (reaction (b)) has been studied from threshold to 450 MeV [see (1985AJ01)] and at Eγ = 132 to 169 MeV (1989KO05), 138 to 146 MeV (1986GL07, 1987GL01), 138.0 to 181.9 MeV (1987JA1F, 1987MA07) and 234 to 449 MeV (1986AR06). At Eγ = 157 to 170 MeV the excitation of 12C*(4.4) is reported (1989PF1A; prelim.). See also (1989KO1Q) and (1984HO24, 1988ST12). For other papers on pion production (including π+ and π-) see the "General" section here, and 12B and 12N. For high energy processes see (1984AL1J, 1984AL1K).
See also (1985AJ01), (1983AR24, 1983TO18, 1984ST18, 1986SH1M, 1988SC1B), (1985GI1G, 1985HO27, 1985MA1G, 1988OC1A), (1989BO1F; astrophysics) and (1984BO18, 1984CA18, 1985AL1K, 1985BO1A, 1985TO15, 1986HO11, 1987BE2A, 1987GOZK, 1987GO37, 1987KI1C, 1987PA1K, 1988AH03, 1988OR02; theor.).
Cross sections and angular distributions of the deuterons corresponding to transitions to 10Bg.s. and/or low excited states have been measured at Eγ ≈ 40 MeV: the results are consistent with E2. There is some evidence also for the excitation of higher states of 10B via non-E2 transitions. For Ebs = 90 MeV, the ratio of the yields of deuterons to protons is ≈ 2%, for particle energies 15 to 30 MeV. For higher particle energies, the ratio decreases: see (1980AJ01) for references. See also (1986SH1M). Momentum spectra for deuterons and tritons (reactions (a) and (d)) are reported at Eγ = 300 to 600 MeV by (1986BA07). The (γ, pn) reaction has been studied at Eγ = 83 to 133 MeV by (1988DA16) and in the Δ-resonance region by (1987KA13). For reaction (c) see (1987VO08). The yield of tritons has been measured for Eγ = 35 to 50 MeV: see (1980AJ01). See also (1985AJ01), (1984AL1J, 1984DO17) and (1985BU1H, 1986BU22, 1986GU1G, 1987BU1A; theor.).
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. For Eγ < 22 MeV, transitions are mainly to 8Be(g.s.) and 8Be*(2.9) with the g.s. transition dominating for Eγ ≲ 14 MeV. For Eγ > 26.4 MeV, 8Be (T = 1) levels near 17 MeV are strongly excited. Surprisingly strong E1 contributions are observed below Eγ ≈ 17 MeV: see (1980AJ01) for references. See also (1986LI22). The ratio for σ(γ, α0)/σ(γ, p0) is 0.029 ± 0.012 at Eγ = 28 MeV (1989FE01). For other breakup processes see (1975AJ02, 1985AJ01). See also (1985CH27; theor.).
Resonance scattering and absorption by 12C*(15.11) have been studied by many groups: see (1980AJ01) and 12.7 (in PDF or PS) here. Inelastic scattering has also been reported to 12C*(4.4, 9.6 ± 0.2, 11.8 ± 0.2, 12.7, 13.3 ± 0.2, 17.2 ± 0.2, 18.3 ± 0.2, 20.5 ± 0.2, 22 - 24 (giant resonance), 26.5 ± 0.4, 29.5 ± 0.3): see (1980AJ01, 1985AJ01). Measurements of the elastic differential cross sections for Eγ = 22.5 to 52.0 MeV (θ = 45°, 90°, 135°) have been reported by (1985WR02). The difference between the (measured) energy-integrated values of σγ and the E1 part of the photoabsorption cross section σE1γ is small and cannot be ascribed to E2 strength (1985WR02). Beyond Eγ = 52 MeV significant E2 strength may be present (1985WR02). For the earlier work see (1985AJ01). See also (1984NA18, 1986BEZM), (1984NA1J, 1985HA1H, 1985MU08) and (1984MA1W, 1985AR07, 1985VE09, 1987FE05, 1987VE03; theor.).
Recent values of the nuclear charge radius are < r2 > 1/2 = 2.472 ± 0.015 fm, 2.464 ± 0.012 fm [2.468 ± 0.012 fm when the dispersion correction is made]: see (1985AJ01). A value obtained from muonic X-rays is displayed in the "General" section here. Elastic scattering has been studied up to 4 GeV: see (1968AJ02, 1975AJ02, 1985AJ01). (1986OF01, 1987OF1A) report evidence for an energy dependence of the elastic form factors, probably due to two-step processes, between Ee = 238 and 431 MeV.
12C states observed in inelastic scattering are displayed in 12.15 (in PDF or PS). The variation of the form factor with momentum transfer yields unambiguous assignments of Jπ = 2+, 0+, and 3- for 12C*(4.4, 7.7, 9.6). Longitudinal form factors show 12C*(16.1, 18.6, 20.0, 21.6, 22.0, 23.8, 25.5) while the transverse form factors show 12C*(15.1, 16.1, 16.6, 18.1, 19.3, 19.6, 20.6, 22.7, (25.5)). 12C*(19.4) may be the expected giant magnetic quadrupole state, Jπ = 2-: see (1975AJ02, 1980AJ01) for references and additional information. The more recent work by (1984HI06, 1987HI09) is also displayed in 12.15 (in PDF or PS). A study of the (e, e'γ) reaction by (1985PA01) shows that the relative phase of the longitudinal and transverse form factors of 12C*(4.4) is negative. Studies of the excitation of the Δ-resonance are reported by (1987OC01; Ee = 537 and 737 MeV) and by (1988BA25; Ee = 653, 1300, 1500, and 1650 MeV). See also (1986OLZY, 1986TH1F, 1987GI1G).
See also (1985AJ01), reaction 35, (1984BU1H, 1984DE1P, 1985BU09, 1987KU05, 1988KO21), (1984HE1F, 1984LI25, 1985HI04, 1985PA1N, 1986HI06, 1986LI1C, 1986PA1C, 1987BE25, 1987DE43, 1987FR1B, 1987HO1D, 1987LI30, 1987RA1O) and (1983NA1E, 1984CA22, 1984CE05, 1984CI1A, 1984DE51, 1984DO14, 1984ER06, 1984KA1G, 1984KR10, 1984KU1E, 1984MO13, 1984RA1H, 1984RA14, 1984RO15, 1984SA1H, 1985BO06, 1985CE09, 1985CH07, 1985FR08, 1985KE1F, 1985KO06, 1985ME1L, 1985MU1F, 1985SA06, 1985SH1L, 1985ST09, 1986AZ01, 1986CZ01, 1986KO30, 1986KU09, 1986MAZF, 1986MU14, 1986PE1E, 1986SA2L, 1986SH01, 1986TR04, 1986ZE1A, 1987AL05, 1987AL1M, 1987CO30, 1987DO12, 1987DR02, 1987FE05, 1987FUZZ, 1987GM03, 1987JI01, 1987RA25, 1987SC26, 1987VOZS, 1988BE01, 1988CA20, 1988CH37, 1988CL03, 1988GU03, 1988GU12, 1988NI08, 1988PA25, 1988TR04, 1989LI1G, 1989MA06, 1989MI1I, 1989OR05; theor.).
I am extremely indebted to Dr. Larry Weinstein for his detailed comments which led to the writeup below.
The inclusive studies by (1983BA28, 1984AR02, 1984OC01) uncovered a lack of understanding of the quasielastic and dip region processes. The more recent studies have focused on (a) quasielastic processes involving various states of 11B [see 11B and (1985VA05, 1985VA16, 1988VA09, 1988VA21)]; (b) quasielastic reaction mechanism studies including longitudinal/transverse separations (1986VA17, 1987UL03, 1988VA09, 1988WE1E); (c) dip and Δ-region reaction mechanism studies (1986LO03, 1989BA03, 1989SE02); and (d) quasifree deuteron knockout spectroscopy to low-lying states of 10B (1989EN01). See also (1987DA20, 1988AV01).
Nuclear spectroscopy studies produce momentum distributions that are well reproduced by DWIA calculations but with occupation numbers that are about 60% of the expected shell-model results (1985VA05, 1985VA16, 1988VA09, 1988VA21, 1987UL03, 1988WE1E).
Studies of the quasielastic longitudinal and transverse response functions versus missing energy have been carried out by (1986VA17, 1987UL03, 1988VA09). See also (1988VA1I, 1988VA1J). (1987UL03) find in the longitudinal response a broad bump at missing energies between 28 and 48 MeV, attributed to knockout from the s-shell. In the transverse response they find this bump on top of a broader feature with a threshold at 28 MeV extending beyond 65 MeV. This broad feature is attributed to two-particle knockout, a non-quasielastic reaction mechanism; it may account for the observed (e, e') transverse-longitudinal difference. This feature is also observed in unseparated data at larger momentum transfers: it appears to grow with momentum transfer (1988WE1E).
(1984CA34) find evidence from the (e, ep0) work for a monopole, 0+, state near Ex ≈ 20.5 MeV which exhausts at least 1% of the EWSR. The decay of states in the giant resonance region via α-particles has been studied by (1987DEZU): the decay is primarily to 8Be*(2.9) (Jπ = 2+). See also (1984FL02, 1986LI22). For other charged particle emission see (1984FL02). For pion emission see the "General" section here, 12B, 12N and (1986SH14, 1988SH36). For the early work see (1980AJ01, 1985AJ01).
See also reactions 27 and 28, 1983BU20, 1984BU18, 1984LI07, 1985LI15, 1986BA85, 1987CAZY, 1987VA1N, 1988BA1D, 1988BOZT, 1988GAZV, 1989BOZZ), (1984LA16, 1984WA1J, 1985BE1K, 1986DE1T, 1986DE1U, 1986DO1N, 1986LA1T, 1987RI1A, 1988HA12) and (1983NA1E, 1984CA22, 1984CI1B, 1984HA1K, 1984NA16, 1984ZI1C, 1985AF03, 1985CA32, 1985CO14, 1985DE20, 1985DO1G, 1985KE1G, 1985LA1F, 1986AK01, 1986CO1U, 1986DE05, 1986GO1T, 1986NI03, 1986RO24, 1986RO22, 1986ST05, 1987AL19, 1987BL10, 1987BO54, 1987CH10, 1987GI07, 1987GOZO, 1987GU21, 1987MO1J, 1987MO24, 1987MO1M, 1987PA1J, 1987ST02, 1987VA15, 1987WE02, 1987YO04, 1988ER05, 1988HO09, 1988HO10, 1988KO13, 1988OC01, 1988SU02, 1988WE03, 1989BR01, 1989HO02, 1989PIZZ, 1989RY03, 1989TA03, 1989TA02, 1989WE1G; theor.).
Angular distributions of the elastic and inelastically scattered pions have been measured at many energies: see 12.16 (in PDF or PS) in (1985AJ01) and 12.16 (in PDF or PS) here. The study by (1987CO17) [Eπ± = 100 to 291 MeV] suggests Jπ = 2- for 12C*(18.25, 19.4) and 4 for 12C*(19.25). 12C*(19.65) is also populated. A study of the giant resonance region suggests states at Ex = 20.0 ± 0.2 and 22.7 ± 0.4 MeV, with Γ = 3.2 ± 0.3 and 1.0 ± 0.2 MeV (1984BL12; Eπ+ = 170 MeV).
The ratio of the cross sections to the 1+; T = 0 and 1+; T = 1 states, 12C*(12.7, 15.1), has been measured at Eπ± = 50 MeV, where it is 7.1 ± 1 [isospin averaged] (1988RI03). The excitation of these two states has also been studied for Eπ± = 80 to 295 MeV by (1988OA03). See also (1988BA27). (1986AN01) have reported inelastic cross sections, including those to the "continuum" above 12C*(9.6) at Eπ+ = 67, 85 and 100 MeV. The elastic excitation function at θ = 175° has been measured for Eπ+ = 100 to 250 MeV (1987DH01). Total reaction cross sections are reported at Eπ± = 50 and 65 MeV (1987ME12). See also (1987BE1R).
(π', γ4.4) angular correlations have been studied at Eπ+ = 65 and 90 MeV (1984SO12) and 116 to 226 MeV (1986OL07, 1988OL02). See also (1985KI05). The (π', γ15.1) angular correlations are reported at Eπ+ = 116 to 226 MeV (1988BA27).
For reaction (b) see 11B and (1984FA11; Eπ± = 220 MeV) and (1987HU02; Eπ+ = 150 MeV). The polarization of protons in the π± A → px process has been studied at 1.5 GeV/c (1984BU11). For studies of (π±, 2p), (π+, pd), and (π±, pn) reactions see (1986AL22, 1986NA03, 1987YO01, 1989YO03). For the (π+, 3p) reaction see (1985TA14, 1987BR17). See also the "General" section here, (1985AJ01) for the earlier work, (1984GO1F, 1989ROZZ), (1984KI16, 1985MI16) and (1985CO03, 1985KA04, 1986PE1E, 1986TA08, 1988ST07; theor.).
Angular distributions of elastic and inelastically scattered neutrons have been studied at many energies up to 350 MeV [see (1980AJ01, 1985AJ01)] and at En = 11.05 and 13.81 MeV (1986HOZY; prelim.; n0, n1), 14.1 and 14.5 MeV (1983HU14; n0, n1), 14.6 MeV (1985HA02; n0), 18.2 MeV (n0; quoted in (1987TO03)), 20.8, 22, 24 and 26 MeV (1985ME16; to 12C*(0, 4.4, 7.7, 9.6, 10.8, 11.8, 13.4, 14.1, 15.1, 16.1 [the latter two at En = 22 and 24 MeV (A.S. Meigooni, Ph.D. Thesis, Ohio University (1984) and R.W. Finlay, private communication)]) and 40.3 MeV (1986WI01; n0). See also (1985FI09) and (1985PE10; theor.). For cross sections and polarization studies see (1985TO02, 1987TO07, 1987TO03, 1988TO01) and 13C in (1991AJ01).
Angular correlations (n1, γ4.4) have been studied at En = 13.9 to 15 MeV: see (1975AJ02). The quadrupole deformation parameter β2 = -0.67 ± 0.04 (1983WO02). For a kinematically complete study of reaction (b) at En = 11 to 35 MeV see (1983AN02): the sequential decay via 12C*(9.6) and 8Beg.s. is clearly observed at the higher energies. See also (1986AN22) and (1980AJ01). For pion production see (1988BU16).
See also (1985MA68, 1985PE1C, 1985WE1D, 1986BO1M, 1986ZH1F, 1987NEZY, 1988WE06), (1985FIZW, 1985HO1J, 1986HAYU), (1986KE1H, 1988AN1F; applications) and (1983KO44, 1983SH1P, 1985AU1C, 1985BE59, 1985DI1B, 1985GU1D, 1985TI08, 1986AL1L, 1986IS1F, 1986LI16, 1986SH35, 1987KO1N, 1987WI16; theor.).
Angular distributions of elastically and inelastically scattered protons have been measured at many energies up to Ep = 1040 MeV: see 12.17 (in PDF or PS) here and (1968AJ02, 1975AJ02, 1980AJ01, 1985AJ01).
12.18 (in PDF or PS) displays the information on excited states of 12C. A summary of the decay of some excited states is shown in 12.7 (in PDF or PS). The angular distributions have been analyzed by DWBA (and CCBA), DWIA, (including microscopic calculations) and DWTA (DW t-matrix approximation with density-dependent interactions). Microscopic DWIA calculations give good results for transitions which take place through the S = T = 1 part of the effective interaction and also gives a reasonable description of the S = T = 0 transition. However the mechanism for the excitation of 12C*(12.71) (S = 1, T = 0) remains a puzzle. At Ep = 402 MeV the differential cross sections for 12C*(12.7, 15.1) (Jπ = 1+) are very similar for large q. This may be due to the smallness of precursor effects [precursor to a pion condensate] (1981ES04).
The spin-flip probability (SFP) for the transition to 12C*(4.4) has been measured for Ep = 15.9 to 41.1 MeV: two bumps appear at ≈ 20 and ≈ 29 MeV. It is suggested that the lower one is due to a substructure of the E1 giant dipole resonance while the upper one results from the E2 giant quadrupole resonance. The SFP has also been studied at Epol. p = 24.1, 26.2, 28.7 MeV (to 12C*(4.44)), at Ep = 42 MeV (to 12C*(12.7)), at Epol. p = 397 MeV (to 12C*(9.6, 12.7, 15.1, 16.1)) [the SFP to 12C*(9.6) is consistent with zero; the others exhibit large SFP at forward angles] and at Ep = 398, 597 and 698 MeV (to 12C*(18.3, 19.4)). See also (1987GRZY; prelim.).
(1980HO07) have measured the angular distribution of γ-rays from the decay of 12C*(12.7, 15.1) at Ep = 21.5 to 27 MeV. Microscopic DW calculations were performed for the A0 and a2 coefficients from these and earlier data. The theoretical calculations underestimate A0 for energies below 35 MeV and are in agreement with the experimental A0 for higher energies. The calculations also predict significant difference in the a2 values for the transitions from 12C*(12.7, 15.1), and these are observed (1980HO07).
(pγ15.1) angular correlations have been studied at Ep = 400 MeV by (1988HI12): the data are best described by a relativistic model of p-nucleus scattering in the impulse approximation. See also (1986SH1X). A search for a short-lived neutral particle emitted in the decay of 12C*(15.1) is reported by (1988DA01) [see for upper limits].
For polarization and yield measurements see 13N in (1986AJ01, 1991AJ01) and (1988FE09, 1989CH08). For other 12C + p interactions see reaction 39, here. For other work and for earlier references see reaction 40 in (1985AJ01).
See also (1983AP1A, 1985WIZW, 1986BA2U, 1986LI1Q, 1986SA2F, 1986TRZZ, 1987RO1F, 1988HI03, 1988LYZZ, 1989OPZZ), (1984GA32, 1984TA1L, 1985BL22, 1985BR1G, 1985CA1B, 1985HO1J, 1985ME16, 1985PE10, 1985SH1C, 1986CA1N, 1986GL1G, 1986HA2K, 1986MC1K, 1987BR32, 1988BO1I), (1987LA11, 1988LE08, 1988SA1B; astrophysics), (1987KO1M, 1988BA2A; applications) and (1983KO44, 1983LY07, 1983ZA09, 1984AM07, 1984LI1J, 1984LI1M, 1984LO20, 1984PH02, 1984SH14, 1985AU1C, 1985BA1Z, 1985CL1B, 1985DA24, 1985EL04, 1985IN01, 1985IV1A, 1985IV1B, 1985PI09, 1985PI11, 1985SH1H, 1985SM06, 1985SP03, 1985TI06, 1985ZH07, 1986BA62, 1986BL03, 1986CO1V, 1986DEZK, 1986DI04, 1986ES01, 1986IN01, 1986IS1F, 1986JA18, 1986KA1Y, 1986LO1A, 1986MO12, 1986PE1E, 1986POZW, 1986SH01, 1986SH35, 1986VD01, 1986YA16, 1987BI20, 1987CUZZ, 1987DA1D, 1987KA1G, 1987LI01, 1987MO13, 1987MU05, 1987NA1H, 1987RO02, 1987SCZV, 1987WI16, 1987ZA1F, 1988BEYI, 1988DA07, 1988HO09, 1988HO1K, 1988NA04, 1988PI02, 1988PR06, 1989TA03, 1989TU1A; theor.).
Antiproton scattering angular distributions have been measured at E(p-bar) = 46.7 and 179.7 MeV (1986LE13, 1984GA32; to 12C*(0, 4.4, 9.6)). See also (1985JA1J; also at 30 MeV; Ph.D. thesis). 12C*(7.7) and some other, unresolved, groups were also populated (1986LE13). Cross section measurements are also reported at 1.45 and 1.8 GeV/c (1984AF1A). The knockout (p-bar, p) reaction has been studied at E(p-bar) = 180 MeV (1985GA02) and 600 MeV/c (1987AS06): there is no evidence for narrow bound or resonant overline p-nucleus states. For a polarization study see (1988MA48). For spectra of 3He and α-particles see (1988MA44). See (1985AJ01) for the earlier work, the "General" section here and (1984DA20, 1985AM01, 1985DA24, 1985LI16, 1986KL01, 1987AD04, 1988IN01; theor.).
Recent work on reaction (a) has involved the distribution of protons [and of deuterons from reaction (c)] associated with backward energetic protons over a wide kinematical range (1985MI09; Ep = 800 MeV). Spectra from coincident proton emission from the continuum have been studied at Ep = 200 MeV by (1988CO02). At Ep = 156 MeV states at 18.4, 19.4, 20.6 and ≈ 22 MeV appear to be involved (1989TEZZ; prelim.). At 2.1 GeV (1984TR09) have searched for interactions between the incident protons and a fast dinucleon constituent inside C. For inclusive proton spectra see (1985SE15, 1988FO06). See also (1985HAZW, 500 MeV; prelim.). For reaction (a) see also 11B and (1984VD01, 1985BE30, 1985DO16). For reaction (b) see 11C and (1985BE30, 1985DO16).
For reaction (c) [and for the (p, p3He) reaction] see (1985DE17, 1984DE1F). See also (1984TR09). At Ep = 56.5 MeV reaction (d) proceeds primarily by sequential α-decay. 12C*(22.2 ± 0.5, 26.3 ± 0.5) which subsequently decay to 8Beg.s. must therefore have natural parity and a significaant T = 0 admixture. 12C*(19.7, 21.1, 26.3) decay to 8Be*(2.9). These states must also have a T = 0 component. It is suggested that 12C*(21.1) has unnatural parity. At Ep = 44.2 MeV 12C*(12.7, 14.1, 21.6, 26.6) are observed in the angular correlation involving α0 and 12C*(21.6, 24.1, 26.6) decay via α1 to 9Be*(2.9) [suggesting 2+ for these states, assuming that only resolved states are involved].
For reaction (e) see (1984NA17). A search for a bound ppπ+ state is reported at Ep = 500 MeV by (1988FR1D, 1988FR1J; prelim.). For isobar production at 3.88 GeV/c see (1987NA11). For inclusive pion production at Ep = 330, 400, and 500 MeV see (1985DI01). See also (1988AB05). For K+ production see (1986AB07, 1988KO36). For η production see (1987BL1L). For other work at high energies see (1986AG1C, 1986CH2H, 1987AG04, 1987AL1J, 1987CH1K, 1987DE1L).
For the earlier work see (1985AJ01). See also the "General" section here, (1986VO17, 1987AR1M, 1988AG1A, 1988BE2B, 1988CHZV), (1985KI1A, 1986BA2D, 1986CH1J, 1987VD1A, 1988LE1I, 1988MO1H, 1988NA1H) and (1983KA1A, 1984GU14, 1985BU04, 1985GA1A, 1985GA1B, 1985KO2C, 1985SM1D, 1986ER1A, 1986GO1U, 1986HO10, 1986OS08, 1986VD01, 1986ZH03, 1987HO1G, 1987HO08, 1987VD1B, 1988BA83, 1988DZ1A, 1988KU16, 1988VD1B, 1989TA03; theor.).
The angular distribution of elastically and inelastically scattered deuterons has been studied at many energies: see (1968AJ02) and 12.22 (in PDF or PS) in (1975AJ02), 12.17 (in PDF or PS) in (1980AJ01), 12.17 (in PDF or PS) in (1985AJ01) and 12.17 (in PDF or PS) here. In addition to well-known states in 12C such as 12C*(4.4) [Ex = 4440.5 ± 1.1 keV] and 12C*(12.7, 15.1) [see 12.10 (in PDF or PS) for charge-dependent matrix element], the population of 12C*((10.8 ± 0.2), (11.8 ± 0.2), 18.3 ± 0.3, 20.6 ± 0.3, 21.9 ± 0.3 (broad), ≈ 27 (broad)) is also reported. See (1980AJ01) for references and for additonal structures which have not been published. Calculated deformation parameters listed in (1980AJ01) are β2 = -0.48 ± 0.02 and 0.47 ± 0.05, and β3 = 0.35 ± 0.06.
Reaction (b) has been studied at Ed = 5.0 to 9.85 MeV and at 56 MeV: see (1980AJ01, 1985AJ01). The breakup of deuterons on C has been investigated at 2.1 GeV (1989PU01). For reaction (c) see 8Be in (1984AJ01). Energy spectra for the (d, 2p) reaction, with the two protons in the singlet (1S0) state, have been studied at Epol. d = 650 MeV and 2 GeV [reaction (d)]: the reaction appears to proceed via a one-step process and therefore can be used to study isospin-spin excitations. The Δ-excitation is observed (1987EL08). For work at very high energies see (1987AG04, 1987AL1J, 1987AR1M, 1987AZ1C, 1988AG1A, 1988SI1B). For high-energy γ-production see (1988TA22). See also 14N in (1986AJ01, 1991AJ01), (1986JA14) and (1984YA01, 1985GA1A, 1985GA1B, 1986IS1F, 1986KA1B, 1987AU1F, 1987SI10, 1988SI04, 1989TU1A; theor.).
Angular distributions of elastically scattered tritons have been determined at Et = 1.0 to 20.0 MeV [see (1975AJ02) and 12.17 (in PDF or PS) in (1985AJ01)] and at 33 and 36 MeV (see 12.17 (in PDF or PS)). See also (1985SA31; theor.).
Angular distributions of 3He ions have been measured for E(3He) = 2 to 217 MeV: see (1968AJ02, 1975AJ02, 1980AJ01, 1985AJ01) and 12.17 (in PDF or PS) here. Parameters of observed 3He groups are displayed in 12.19 (in PDF or PS).
Angular distributions of the 3He groups to 12C*(15.11, 16.11, 16.57, 19.55) have been compared with those for the tritons to 12N*(0, 0.96, 1.19, 4.25) in the analog (3He, t) reaction: the correspondence is excellent and suggests strongly that these areT = 1 isobaric analog states. See also 12.12 (in PDF or PS) in (1980AJ01) and 12.19 (in PDF or PS) here. 12C*(4.4, 15.2, 18.4, 18.9, 21.3, 23.5, 25.9, 28.8) all appear to correspond to E2 transitions: their strengths add up to 46% of the EWSR (energy-weighted sum rule). See (1980AJ01) for references and (1985AJ01) for additional comments.
For reaction (b) see (1985AJ01). Inclusive proton and deuteron spectra have been studied at E(3He) = 52 MeV by (1984AA01). For reaction (c) see 13C and 15O in (1991AJ01) and (1986KA44). For π± production see (1986MI25). See also 15O in (1986AJ01, 1991AJ01), (1987AD1C), (1987MA2D) and (1985GO19, 1985KH08, 1985SH1A, 1986EV01, 1986EV02, 1986IS1F, 1986KA1B, 1986ZE04, 1987RA36, 1987TR01; theor.).
Angular distributions have been measured at many energies up to 1.37 GeV: see 12.24 (in PDF or PS) in (1968AJ02), 12.22 (in PDF or PS) in (1975AJ02), 12.17 (in PDF or PS) in (1980AJ01), 12.17 (in PDF or PS) in (1985AJ01) and 12.17 (in PDF or PS) here. Parameters of observed states of 12C are displayed in 12.19 (in PDF or PS). The quadrupole deformation parameter β2 = -0.30 ± 0.02 [see (1980AJ01)], -0.40 ± 0.02 (1983YA01), while β3 ≈ 0.23 [see (1980AJ01)] and β4 = +0.16 ± 0.03 (1983YA01; see also for a review of deformation parameters). In the region of the GDR prominent gross structure is observed consisting of two ≈ 2 MeV wide peaks at 26.2 and 29.2 MeV (1987KI16; see also for a discussion of deformation parameters).
Angular correlation measurements (α1, γ4.4) have been carried out for Eα = 10.2 to 104 MeV [see (1980AJ01, 1985AJ01)] and at 25 to 30 MeV (1984TE01, 1986GU06, 1986ZE1C; see for a study of the spin tensors for 12C*(4.4)). Reaction (b) has been studied for Eα up to 700 MeV [see (1975AJ02, 1985AJ01)], at 27.2 MeV (1986KO1B; prelim.) and at 31.2 MeV (1986XI1A). For cross sections see 16O in (1986AJ04) and (1987BU27). For other comments on these two reactions see (1985AJ01). For π± emission see (1986ALZL, 1986ALZK, 1987AL1G; prelim.). For high-energy γ-production see (1988TA22). For work at very high energies see (1984AN1H, 1985AB1A, 1986BA3D, 1987AG04, 1987AL1J, 1987AR1M, 1988AG1A, 1988SI1B).
See also (1984SA28, 1985XI1C, 1987GOZL, 1988AI1B, 1989ES06, 1989LE09), (1983SA07, 1985HO1J), (1988MU1G, 1989LA1G; astrophysics) and (1983AL1F, 1983GE10, 1983GO27, 1985GA1A, 1985GA1B, 1985KH08, 1985SA09, 1986SH1I, 1985ZE02, 1985ZE04, 1986BA11, 1986BE45, 1986EL08, 1986LI1U, 1987BA83, 1987CUZZ, 1987KA1G, 1987KH06, 1987KO1E, 1987KU18, 1987NO05, 1987SA55, 1987VOZS, 1987ZE02, 1988BA1Q, 1988GR1C, 1988KH08, 1988KU1D, 1988KUZU, 1988MA10, 1989TU1A; theor.).
Angular distributions in reactions (a) and (c) have been studied at E(6Li) = 4.5 to 210 MeV and E(7Li) = 4.5 to 131.8 MeV: see (1975AJ02, 1980AJ01, 1985AJ01) for the earlier work and 12.20 (in PDF or PS) here. See also (1989TRZZ). Reaction (b) takes place via 12C*(0, 4.4, 7.7): see (1985AJ01, 1986AJ04) and (1985CU04). See also (1988AR22). For VAP measurements (reaction (a)) see (1989VA04; g.s., 4.4) and (1987TA21; g.s.). See also (1988TA08, 1989TRZZ) and 18F in (1987AJ02).
A search by (1987EY01) for the distribution of the E0 strength determines 10%, (5 ± 1)% and (5 ± 2)% of the EWSR, respectively for 12C*(7.7, 10.3) and for 19 < Ex < 21.5 MeV. For fusion and other cross section measurements (reaction (a)) see (1987PA12). For the 6Li and 7Li + C interaction cross section at 790 MeV/A see (1985TA18). For pion emission see (1984BE35, 1984CH16). The elastic scattering in reaction (d) has been studied at E(7Be) = 140 MeV (1989YA02). See also (1986DAZP, 1986SHZP, 1986YOZU), (1984HA53, 1986KA1C, 1986MO1E) and (1983DE48, 1983GO18, 1984MU1D, 1984UH1A, 1985CO21, 1985HE25, 1985KH08, 1985SA13, 1985SH1A, 1986BE45, 1986IO01, 1986KA1B, 1986MI24, 1986SA15, 1986SAZL, 1986SA1D, 1986YO1A, 1987AR13, 1987KA1I, 1987SA21, 1988DEZU, 1988KH08, 1988OT01, 1988SA10, 1988SA15, 1988SE07, 1989KAZY; theor.).
Angular distributions have been obtained at E(9Be) = 14 to 158.3 MeV and at E(12C) = 12 to 21 and 65 MeV: see 12.20 (in PDF or PS) here and (1980AJ01, 1985AJ01). For fusion and yield measurements see (1985AJ01) and (1985DE22). For the 9Be + C interaction cross section at 790 MeV/A see (1985TA18). See also (1988HAZS), (1984FR1A, 1984HA53, 1985BE1A, 1985CU1A) and (1984HA43, 1986BA69, 1986HA13, 1986KA22, 1986MI24, 1988KH08; theor.).
Angular distributions in reaction (a) have been measured at E(10B) = 18 and 100 MeV. Those for reaction (b) have been studied at E(11B) = 10.4 to 100.0 MeV and E(12C) = 15 to 87 MeV: see (1980AJ01, 1985AJ01) and 12.20 (in PDF or PS) here. For fusion and yield studies see (1985AJ01) and (1985MA10, 1986MA13). See also (1984DEZX, 1984HAZK, 1987SAZW, 1988SAZT). See also (1987PO15), (1984FR1A, 1984HA53, 1985BE1A, 1985CU1A, 1986MA19, 1988MA07), (1982BA1D, 1985BA1T; astrophysics) and (1984HA43, 1984IN03, 1985KO1J, 1986BA69, 1986HA13, 1986RO12, 1988DI08; theor.).
Angular distributions of the magnetic substate population for the single and mutual 12C*(4.4) excitation have been measured by (1985SU07) for E(12C) = 38 to 110 MeV. The yields of 12.7 and 15.1 MeV γ-rays have been studied at E(12C) = 180 MeV (1988HA23), and hard photon collisions have been investigated at E(12C) = 576 to 1008 MeV (1986GR19). For other studies of excitation functions and reaction cross sections see (1984KO12, 1984SI15, 1985KO17, 1985KO24, 1985ME1K, 1985PA24, 1986HAZA, 1986HA30, 1986SA29, 1987HO11, 1987KO12, 1988DE18, 1988PA04, 1989LI10, 1989PA05). See also (1984HO1K). For a study of the effects of vacuum polarization in hadron-hadron scattering see (1989VE03). For reaction (b) see (1986SH10, 1988CAZU) and 16O in (1986AJ04): the excitation of 12C*(9.6, 10.8, 14.1) is reported at E(12C) = 90 to 140 MeV. For fragmentation studies see (1985HA1U, 1985KR03, 1986EN1D, 1986FO04, 1987FO08, 1988FO03, 1988KI05). See also (1985KR21, 1986LIZP, 1987PO15) and (1989CO1C, 1989HA43; theor.).
For pion production see (1983AN1L, 1984AG1A, 1984BE35, 1984CH16, 1985AR1M, 1986AN40, 1988BA21, 1988NO09). See also (1985OB1A) and the "General" section here. For other studies at very high energies see (1984AD1C, 1984AD1B, 1984AN1H, 1985RO12, 1986AG1B, 1986AN1X, 1986CH2H, 1987AD1E, 1987AG04, 1987AG1A, 1987AL1J, 1987AN20, 1987AR1M, 1988AG1A, 1988SI1B).
See also (1985GO1H, 1985SU16, 1985VI03, 1985XI1B, 1986BL1K, 1986BL1L, 1986CO02, 1988HAZS, 1988KW1B, 1988SAZT, 1989OG03), (1982CI1C, 1984BR1L, 1984FR1A, 1984GE1D, 1984HA53, 1984NA1D, 1984TA1L, 1984TR1E, 1985BE1A, 1985CU1A, 1985NA1B, 1986BA2D, 1986BE2H, 1986BE1D, 1986CA30, 1986DU1N, 1986GR1K, 1986SN1B, 1986ST1J, 1987BA1G, 1987BL1D, 1987BR1R, 1987GE1B, 1987HO1C, 1987SC1D, 1988BA12, 1988BE1W, 1988BO46, 1988CA1L, 1988HA1R, 1988RA1G, 1989BL1D), (1982BA1D, 1985BA1T, 1986MA44, 1987RO25, 1989KH02; astrophysics) and (1983SH1Q, 1984AI02, 1984CA28, 1984DA1M, 1984GA1G, 1984GA12, 1984HA43, 1984KA1H, 1984LA1L, 1984SH18, 1984TR14, 1984ZA1B, 1985AI1A, 1985AI1B, 1985AM1B, 1985BA42, 1985BA63, 1985BL09, 1985BL17, 1985BO1A, 1985CH03, 1985CS02, 1985GR1F, 1985GU1J, 1985HA1N, 1985HU04, 1985IV1B, 1985KA1W, 1985KA1X, 1985KH1E, 1985LA14, 1985LE25, 1985LI1K, 1985MA1L, 1985ME14, 1985ME15, 1985MR1A, 1985NO06, 1985PA1P, 1985SA1D, 1985SH1A, 1985TA07, 1985TA12, 1985TO01, 1985TO04, 1985UM01, 1985VA17, 1986AB1H, 1986BA01, 1986BA30, 1986BA1D, 1986BA62, 1986BL05, 1986CA26, 1986CO17, 1986CS1A, 1986CS01, 1986DE07, 1986DI1D, 1986FA1A, 1986GA1F, 1986GR1M, 1986GR1A, 1986HA1Z, 1986HA13, 1986HN01, 1986HO1P, 1986KA22, 1986KA1B, 1986KH04, 1986KI1L, 1986MA44, 1986NI01, 1986OR01, 1986PH01, 1986POZW, 1986PR1C, 1986PR01, 1986RE05, 1986RO26, 1986SA03, 1986SA30, 1986SA1D, 1986SH04, 1986ST1N, 1986VI07, 1986WU03, 1986YA1U, 1987AB1K, 1987AR13, 1987AS05, 1987BA2D, 1987BA50, 1987BI20, 1987BO45, 1987BO28, 1987DA1L, 1987DI1A, 1987FR06, 1987GU13, 1987KH06, 1987KU1B, 1987MA17, 1987MA1J, 1987MA2D, 1987OC1B, 1987OH02, 1987OH08, 1987OH09, 1987OH13, 1987PA24, 1987PH01, 1987RA28, 1987RE03, 1987RE11, 1987RE1G, 1987SC33, 1987ST1E, 1987YA1L, 1988AB1E, 1988AB1F, 1988AD1C, 1988AI1D, 1988AS03, 1988BA04, 1988BA2X, 1988BA43, 1988BA37, 1988BO21, 1988BR04, 1988BR20, 1988BR29, 1988CA08, 1988DE39, 1988DJ1A, 1988FR14, 1988GA1C, 1988GAZW, 1988HE12, 1988IW02, 1988KA1S, 1988KH07, 1988KH09, 1988KH1B, 1988KHZX, 1988LE20, 1988MA10, 1988NA10, 1988OH01, 1988OH09, 1988PO06, 1988PR02, 1988PR04, 1988SE1D, 1988TO02, 1988WU1A, 1988ZU01, 1988ZW1A, 1989EL01, 1989MR01, 1989SH05, 1989TU1A; theor.).
Angular distributions for reaction (a) have been studied at E(12C) = 15 to 87 MeV and E(13C) = 12, 36 and 87 MeV [see (1975AJ02, 1985AJ01)] and at E(12C) = 94.5 MeV (1986BA80; g.s.) and E(13C) = 16.3 to 20.6 MeV (1984FR05; g.s.), 17.3 to 26.5 MeV (1988VO01; g.s.), 36 MeV (1985BY01; 12C*(4.4)) and 260 MeV (1985BO39; 12C*(0, 4.4)). Elastic angular distributions (reaction (b)) are reported at E(12C) = 12 to 20 MeV [see (1980AJ01)] and at E(14C) = 31.0 to 56 MeV (1985KO04). The spin-flip probability to 12C*(4.4) has been studied at E(13C) = 36 and 56 MeV by (1985BY01). See (1985AJ01) for the earlier work. For yield and cross section measurements see (1985KO04, 1985RI1C, 1986HA30, 1986STZY, 1987KO12) and (1985AJ01).
See also 13C and 14C in (1991AJ01), (1984FR1A, 1984HA53, 1985BE1A, 1985CU1A, 1986SN1B, 1987IM1C, 1988BE1W, 1988JA14, 1989VO1D), (1982BA1D, 1985BA1T; astrophysics) and (1983HU1C, 1984IN03, 1984SA31, 1984VO11, 1985HU04, 1985IM1B, 1985KO1J, 1985SA1D, 1985VO01, 1986BA1D, 1986BA69, 1986EL02, 1986HA13, 1986KA1B, 1986SA1D, 1986VI08, 1987AR1E, 1987BO48, 1987FR06, 1987IM01, 1987KAZK, 1987MA22, 1988BR29, 1988KA27, 1988PA07; theor.).
Angular distributions (reaction (a)) have been measured at E(14N) = 21 to 155 MeV [see (1975AJ02, 1980AJ01, 1985AJ01)] and at E(14N) = 150 MeV (1986GO1H; prelim.). Angular distributions for reaction (b) are reported at E(15N) = 31.5 to 94 MeV: see (1980AJ01, 1985AJ01). High-energy γ-ray emission has been studied at E(14N) = 280 to 560 MeV (1986ST07). See also (1987ST1F). For yield, fragmentation and cross-section measurements see (1985AJ01) and (1985CA01, 1986HA1F, 1986MO13, 1987GO01, 1987ST01, 1988KI06). For the 12C(14N, d12C)12C reaction see (1985ARZW, 1986AR1G; prelim.).
See also 14N and 15N in (1991AJ01), (1987VE1D, 1988HAZS), (1984FR1A, 1984HA53, 1985BE1A, 1985CU1A, 1987GE1B, 1989BL1D), (1982BA1D, 1985BA1T; astrophysics) and (1984HA43, 1985HU04, 1985KO1J, 1985VI09, 1986BA62, 1986BA69, 1986HA13, 1986POZW, 1986RE14, 1987BI20, 1987RE03, 1987RE11, 1988BA2X, 1988BA37, 1988HE12, 1988PR02, 1989SH05; theor.).
Angular distributions have been measured at E(16O) = 17.3 to 1503 MeV and at E(12C) = 65 to 76.8 MeV: see (1975AJ02, 1980AJ01, 1985AJ01) and 12.20 (in PDF or PS) here. The excitation of 12C*(0, 4.4, 14.1, 26) has been reported. The latter is due to the wide (Γ ≈ 4 MeV) giant quadrupole resonance. It contains 25+15-10% of the E2 strength: see (1985AJ01).
For fusion, yield, cross-section and fragmentation studies see (1985AJ01) and (1984TS07, 1985BE02, 1985BE40, 1985CA01, 1985KA03, 1985MU18, 1986CH27, 1986CH41, 1986GA13, 1986HA30, 1986IK03, 1987SU03, 1988KO17). See also (1984RU1A, 1987NA1C, 1988SZ02, 1989KRZX, 1989WE1E). For work at very high energies see (1987YO1A).
See also 16O in (1986AJ04), (1988CAZV, 1988HAZS), (1982CI1C, 1984GE1D, 1984HA53, 1984SN01, 1984TR1E, 1985BE1A, 1985CU1A, 1985GA1J, 1985KA1J, 1985SN1A, 1986RE1A, 1986SN1B, 1987BA1G, 1987BO1H, 1987HO1C, 1988RA1G, 1989CI1C, 1989ST1G), (1982BA1D, 1985BA1T; astrophysics) and (1983HU1C, 1984FR1A, 1984HA43, 1984IN03, 1984KA1H, 1984LA1L, 1984SA31, 1985AI1A, 1985BA63, 1985HU04, 1985HU1C, 1985KA1X, 1985KA28, 1985KO1J, 1985ME14, 1985NO1E, 1985SA1D, 1985TR1D, 1985VI09, 1986BA1D, 1986CH44, 1986DE15, 1986DE40, 1986HA13, 1986KA1B, 1986KL06, 1986POZW, 1986SA1D, 1986WU03, 1987AR13, 1987BA50, 1987DA02, 1987PA24, 1987SC33, 1988AB1E, 1988AB1F, 1988BA43, 1988BR04, 1988BR20, 1988BR29, 1988FR14, 1988JI02, 1988KA13, 1988KO27, 1988SE1D, 1989EL01, 1989MA25; theor.).
The elastic scattering angular distributions have been studied at E(17O) = 30.5 to 35 MeV and at E(18O) = 32.0 to 140 MeV [see (1980AJ01, 1985AJ01)] and at E(17O) = 40 to 70 MeV (1986FR04). For fusion, yields, and cross-section measurements see (1985BE40, 1985BE37, 1985CA01, 1986FR04, 1986GA13) and (1985AJ01). For the decay of 18O* into 14C + α, see reaction 34 in 18O (1987AJ02). See also (1984FR1A, 1984HA53, 1989CI1C, 1989FR04), and (1986CI01, 1986HA13, 1987AR1E, 1987MO27, 1987VO05, 1988TH02, 1988THZZ; theor.).
Angular distributions have been measured at E(12C) = 30.0, 40.3, 50.0 and 60.1 MeV and at E(19F) = 40, 60, and 68.8 MeV [see (1980AJ01, 1985AJ01)] as well as at E(19F) = 29.3 to 34.8 MeV (1984MA32; elastic) and E(12C) = 30.0, 40.3, 50.0 and 60.1 MeV (1988TA12; 12C*(0, 4.4) and several states in 19F). The substate population probability for 12C*(4.4) has been studied by (1986IKZZ) at E(19F) = 63.8 MeV. For fusion and yield measurements see (1985AJ01) and (1984MA32, 1986GA13, 1986VO12). For the α-decay of 19F* see reaction 42 in 19F in (1987AJ02) and (1985SM04). See also (1986MA1Z), (1984FR1A, 1984HA53) and (1985HU04, 1986HA13, 1986HE1A, 1987CO01, 1988DI08; theor.).
Elastic angular distributions (reaction (a)) have been measured at E(12C) = 20 to 77.4 MeV and at E(20Ne) = 65.7 MeV: see (1980AJ01, 1985AJ01). For fusion, reaction cross section, yield and evaporation residue studies see (1985AJ01) and (1984KO12, 1984RA10, 1985MU18, 1985OS05, 1987KO12, 1987SI06). See also (1985FL1B). For pion production see (1985AJ01) and (1983AN1L). For other work at very high energies see (1984AN1H, 1987AN20, 1988DU01).
See also (1983AN1K, 1986BL1K), (1984FR1A, 1984HA53, 1984NA1D, 1984ST1B, 1985BE1A, 1985CU1A, 1985ST1B, 1986IK03, 1986ST1J, 1987LA05, 1987SC1D, 1988BO46, 1989CI1C) and (1984HA43, 1984IN03, 1984SH1T, 1985CH11, 1985GA1G, 1985GU1J, 1985HU04, 1985KO1J, 1986GA1F, 1986GI03, 1986HA13, 1986HE1A, 1987SC33, 1988IW02; theor.).
Elastic angular distributions have been measured at E(12C) = 20 to 60 MeV (reaction (a)) and at E(12C) = 20 to 56 MeV (reaction (b)): see (1985AJ01). For fusion, yields and cross-section measurements see (1985AJ01) and (1986GL03, 1988DU11). The fission of 24Mg into 2 12C (involving 12C*(0, 4.4)) has been studied by (1986FUZW; prelim.). See also (1982CI1C, 1982ME1A, 1984FR1A, 1984HA53, 1986BE1D, 1987KA2A, 1987LA05, 1988RA1G, 1989CI1C) and (1985AN16, 1985LE25, 1986BO14, 1986HA13, 1987BR1H, 1987GR04, 1988AY03, 1988KU1H; theor.).
Angular distributions have been measured at E(12C) = 30.0 to 39.9 MeV and at 82 MeV: see (1985AJ01). For fusion, yield, and breakup measurements see (1985AJ01) and (1984KO12, 1985HA19, 1987KO12). See also (1987PO15). For work at very high energies see (1986AN1X). See also (1985XI1B, 1986BL1L), (1984FR1A, 1986CA30, 1988SN1A) and (1984FO21, 1984NA27, 1986POZW, 1986RO12, 1987ST1E, 1988TO02, 1989SH05; theor.).
Elastic angular distributions have been studied for reaction (a) at E(12C) = 19 to 186.4 MeV and at E(28Si) = 58.3 to 116.7 MeV [see (1980AJ01, 1985AJ01)] as well as at E(12C) = 56, 59, 66 and 69.5 MeV (1985SH1K) and 65 MeV (1988YA06).
Alpha-γ angular correlations have been studied at E(28Si) = 112.3 and 142.7 MeV: 12C*(4.4) is found to be produced almost entirely in the m= 0 magnetic substate (1986RA08). For fusion, yield and breakup measurements see (1985AJ01) and (1984SH19, 1986HA33, 1987ZH1G). See also (1985SAZZ, 1986FEZY, 1986HAZS, 1987SHZY, 1988MAZZ). For pion production see (1983AN1L). For other work at very high energies see (1987AN20).
See also (1988SA1S, 1988SH33), (1982CI1C, 1984FR1A, 1984HA53, 1986BE2H, 1987LA05, 1989CI1C) and (1986GR1A, 1986KUZZ, 1987AR13, 1987BR1A, 1987KI12, 1987SH06, 1988AL06, 1988AY03, 1988KU1G, 1988KU1H; theor.).
Elastic angular distributions are reported at E(12C) = 35.8 MeV and E(32S) = 73.3 to 160 MeV [see (1980AJ01, 1985AJ01)] as well as E(32S) = 194, 239 and 278 MeV (1987HI10). For fusion, yield and evaporation residue studies see (1985AJ01) and (1985KO21, 1986PL02, 1987HI10, 1988AR21). See also (1987LA05) and (1989CI1C).
The elastic scattering in all three reactions has been studied at E(12C) = 51.0, 49.9 and 49.9 MeV, respectively [see (1985AJ01)] and, for reaction (a), at E(12C) = 180, 300 and 420 MeV (1986SA29). For fusion, yield, cross-section and fragmentation studies see (1980AJ01, 1985AJ01) and (1984GR20, 1984KO12, 1986SA29, 1987KO12). See also (1985XI1B), (1989BE17, 1989GR04) and (1984SH1T, 1985BL18, 1986CH20, 1986CH38; theor.).
The decay is mainly to the ground state via an allowed transition. Branching ratios to other states of 12C are displayed in 12.21 (in PDF or PS). The half-life of 12N is 11.000 ± 0.016 ms (1978AL01). See also (1968AJ02). The ratio of the branching ratios 12N/12B for the decays to 12C*(4.4) is 1.528 ± 0.027 (1988NA09). See also (1985AJ01). This leads to the following values for the mirror asymmetries of 12B and 12N for decay to 12C*(0, 4.4): δg.s. = +0.129 ± 0.008 (1978AL01), δ4.4 = +0.066 ± 0.018 (1988NA09). See also (1989KR1C).
The decay of the giant resonance in 13C takes place predominantly to 12C*(15.1, 16.1) [and to their analogs in 12B]. Below Eγ = 21 MeV transitions to 12C*(4.4) are dominant: see (1980AJ01). See also 13C in (1991AJ01).
Angular distributions (reaction (a)) have been measured at Eπ+ = 90 to 170 MeV to 12C*(0, 4.4, 7.7, 9.6, 12.7, 14.1, 15.1, 16.1, 19.1, 20.6, 22.9, 25.3): an energy dependent ratio for the excitation of 12C*(12.7, 15.1) is reported. Similarities in the population of states seen in this reaction and in the (p, d) reaction are observed. Angular distributions at Eπ+ = 32 MeV are also reported: see (1985AJ01). For reaction (b) see (1988POZV).
Angular distributions have been measured at Ep = 8 to 800 MeV [see (1980AJ01, 1985AJ01)], at Ep = 18.6 MeV (1986GO23, 1987GO27; 12C*(0, 4.4)), 41.5 MeV (1987CA20; 12C*(0, 4.4, 12.7, 15.1, 16.1)) and 800 MeV (1984SM04; 12C*(0, 4.4, 12.7, 14.1, 15.1, 16.1)) and at Epol. p = 119 MeV (1987LE24; 12C*(0, 4.4, 7.7, 9.6, 12.7, 14.1, 15.1, 16.1, 16.6, 17.8, 18.16 ± 0.07, 18.8, 19.9, 20.3, 20.6)) and 500 MeV (1984OH06; g.s.). The population of 12C*(10.3, 15.4) is also reported, and the Γc.m. of the structures at Ex = 18.2, 18.8, 19.9, 20.3 and 20.6 MeV are, respectively, 240 ± 50, 120 ± 30, ≈ 400, ≈ 220 and ≈ 210 keV (1987LE24). (1984SM04) report structures at 20.61 ± 0.04 and 25.4 ± 0.1 MeV, the latter with Γ ≥ 0.5 MeV. The earlier work [see (1980AJ01)] indicated states at 17.76 ± 0.02 [80 ± 20], 18.80 ± 0.04 [80 ± 30], 21.5 ± 0.2 [< 200] and 22.55 ± 0.05 [< 200] MeV [the numbers shown in brackets are Γc.m., in keV].
Angular distributions have been studied at Ed = 0.41 to 27.5 MeV [see (1975AJ02, 1980AJ01)] and 18 MeV (1988GO02, 1988GU20; t0, t1) as well as Epol. d = 29 MeV [to 12C*(0, 4.4, 12.7, 15.1, 16.1)]: see (1985AJ01). For charge-dependent matrix elements between 12C*(12.7, 15.1) see 12.10 (in PDF or PS). See also (1986GU1J; applications) and (1988GUZW; theor.).
Angular distributions have been measured at many energies up to E(3He) = 45 MeV [see (1980AJ01, 1985AJ01)] and at 22.7 MeV (1987VA1I; α0, α1; prelim.). See (1984VA39, 1985VA1E, 1986ZE1C) for a study of the spin tensors for 12C*(4.4).
A study of reaction (b) leads to Γα/Γ for 12C*(15.11) = (4.1 ± 0.9)%; together with the other parameters for the decay of the state (see 12.7 (in PDF or PS)) this leads to Γα = 1.8 ± 0.3 eV. If this isospin-forbidden α-width is the result of mixing between 12C*(12.71, 15.11) via a charge-dependent interaction the matrix element is 340 ± 60 keV: see, however, 12.10 (in PDF or PS) here, and (1980AJ01). See also (1987BA2B, 1987ZE02, 1988GOZB; theor.) and 16O in (1986AJ04).
At E(7Li) = 34 MeV angular distributions have been observed for the reactions to 12C*(0, 4.4) + 7Li*(g.s., 0.48) and 8Li*(0, 0.95) in all combinations. While 12C*(0, 4.4) are dominant in the two spectra, 12C*(7.7, 9.6) and, in reaction (a) at E(6Li) = 36 MeV, 12C*(12.7), are also populated: see (1980AJ01) and (1987CO16; reaction (b)).
Angular distributions have been reported for reaction (a) at E(13C) = 16.0 to 50.0 MeV : (see (1985AJ01) [also excitation functions]) and at E(13C) = 20.0 to 27.5 MeV (1988BI11) for reaction (b). See also (1984BA31) and (1987TH04; theor.). For reaction (c) see (1989FR04). See also (1980AJ01).
Angular distributions have been measured at Ep = 14.5, 18.5, and 39.8 MeV: see (1975AJ02). At Ep = 54 MeV angular distributions are reported to two states at Ex = 27.57 ± 0.03 and 29.63 ± 0.05 MeV [Γc.m. ≲ 200 keV]: their identification as the first T = 2 states is supported by the similar angular distributions to the first two T = 2 states in 12B, reached in the (p, 3He) reaction [see reaction 28 in 12B]. The lower T = 2 state is well fitted by L = 0; the angular distribution to 12C*(29.63) is rather featureless. It is suggested that its shape is somewhat more consistent with L = 0 than with L = 2 (1976AS01): [(1976BA24) has suggested that the second T = 2 state in A = 12 may have Jπ = 0+.] It is not excluded that the group to 12C*(29.63) may be due to unresolved states (1976AS01). (1976AS01) report Γp/Γ ≈ 0.3 ± 0.1 and Γα1/Γ < 0.1 for the first T = 2 state and Γp/Γ = 0.8 ± 0.2, Γp0/Γ ≈ 0.4 and Γα/Γ ≈ 0.2 for 12C*(29.63). (1978RO08) report Ex = 27595.0 ± 2.4 keV, Γ ≤ 30 keV for the first T = 2 state and calculate the decay properties for two values of the total width, 0 and 30 keV. Branching ratios for the decays to 8Be(0) + α; 11B*(0, 2.12, 4.45, 5.02, 6.74 + 6.79) + p; and 10B(0) + d are, repectively, (10.5 ± 3.0)%; (3.0 ± 2.2)%, (8.0 ± 2.3)%, (0 ± 3.3)%, (8.4 ± 3.2)%, (8 ± 5)%; and (2.8 ± 2.0)% (1979FR04).
Angular distributions (reaction (a)) have been studied at Ep = 7.5 to 52 MeV [at the higher energies to 12C*(12.7, 14.1, 15.1, 16.1)] as well as to 12C*(0, 4.4): see (1980AJ01). For reaction (b) see (1985DE17) and (1986VDZY). See also (1987VD03, 1987VD1A) and (1986GO28; theor.).
Observed α-particle groups are displayed in 12.19 (in PDF or PS). Angular distributions have been measured at energies up to 40 MeV: see (1980AJ01) [also for Jπ assignments]. See also (1987SI1D; applications), (1983US01; theor.) and 16O in (1986AJ04).
See (1988SH1E; theor.).
Angular distributions of α0 and α1 have been measured for Ep up to 43.7 MeV. At the highest energy the angular distributions to the 0+ states 12C*(0, 7.7, 17.8) are fitted by L = 1. The distributions to 12C*(14.1, 16.1) [Jπ = 4+, 2+] are consistent with L = 3; see (1980AJ01). For work on cross sections and resonances see 16O in (1986AJ04) and (1988HO1F). See also (1987WE1C, 1988CA26; astrophysics) and (1984BE1A, 1984HA1Q, 1986LE1L, 1986RO18, 1988GN1A; applications).
This reaction proceeds primarily to 12C*(0, 4.4) at Ep = 101.5 MeV (1984CA09): 12C(14.1) is also populated. The breakup into 4α has been studied by (1986VD04). See also (1985AJ01), (1987LA11, 1988LE08, 1988MU1G; astrophysics) and (1985VD03, 1987VD1A) and (1986GO28; theor.).
Angular distributions have been measured at Ed = 12.7 to 80 MeV [see (1980AJ01, 1985AJ01)], at 54.2 MeV (1984UM04; 12C*(0, 4.4, 7.7, 9.6, 14.1)) [see also for spectroscopic factors] and at Epol. d = 18 and 22 MeV (1987TA07; 12C*(0, 4.4)) and 51.7 MeV (1986YA12; 12C*(0, 4.4, 14.1)). For polarization measurements see 18F in (1987AJ02).
At Eα = 90 MeV angular distributions involving 12C*(0, 4.4) (reaction (a)) have been analyzed by PWIA and DWBA: Sα = 2.9 ± 0.5 and 0.70 ± 0.23, respectively. At Eα = 65 MeV angular distributions involving 8Beg.s. (reaction (b)) and 12C*(0, 4.4, 7.7, 9.6, 14.1) have been measured [the ground state distributions have also been studied for Eα = 55 to 72.5 MeV]: Sα = 0.25, 1.07, 0.05, 1.40 for 12C*(0, 4.4, 7.7, 14.1): see (1980AJ01) for references.
For reaction (a) see (1988WE17) and 13C in (1991AJ01). For reaction (b) see (1986CA24) and 20Ne in (1987AJ02). See also (1988AU03), (1984ME10, 1989VO1D) and (1984AP03, 1984KO13, 1987GA1L, 1988GA19, 1988GA1L; theor.).
Angular distributions involving 12Cg.s. have been studied at Ep = 7.9 to 18.6 MeV (1987KI26).
See (1986GO26; Ed = 13.6 MeV).
The fission of 24Mg has been studied at Ep = 190 MeV (1987DA01).
Angular distributions have been reported at Eα = 22.8 to 25.4 MeV and at 90 MeV [see (1980AJ01)], at 25.13 to 27.76 MeV (1986SK01) and at 27.8 to 29.4 MeV (1989ES06). See also (1987SH1B) and (1988SH1F; theor.).
The fission of 24Mg has been studied at E(24Mg) = 357 MeV (1986WI14).