(See Energy Level Diagrams for 9B)
GENERAL: See also (1966LA04) and Table 9.9 [Table of Energy Levels] (in PDF or PS).
Model calculations: (1966BA26, 1966EL08, 1967ST1C, 1971CO28, 1972LE1L, 1973HA49).
Special levels: (1966BA26, 1966EL08, 1967BA59, 1967ST1C, 1969HA1G, 1970TO1E, 1971CO28, 1971LI30, 1972BE1E).
Astrophysical questions: (1970BA1M).
Other topics: (1967CA17, 1967CH1H, 1970SA05, 1972AN05, 1972HA57, 1972CA37, 1972LE1L, 1972PN1A, 1973JU2A).
Ground state properties: (1966BA26, 1966EL08, 1968PE16, 1969HE1N, 1969JA1M, 1969LE1D, 1971AU1G, 1972LE1L).
The total cross section for reaction (a) has been measured from threshold to E(3He) = 3.5 MeV: it increases monotonically reaching the value 4.3 mb at 3.5 MeV (1973MCZW). No structure is observed in the n0 excitation curve for E(3He) = 4.0 to 5.7 MeV (1967VA24). The yield of 8B has also been measured for E(3He) = 8.9 to 26.5 MeV (1973MA24). See also (1966FA1A) and 8B.
The excitation functions for protons leading to 8Be*(0, 2.9) [p0, p1] have been measured for E(3He) = 0.9 to 17 MeV (reaction (b)). Resonances are reported at E(3He) = 1.6 MeV (Γ = 0.25 MeV) [1.68 MeV: (1969VI05). Jπ = 3/2- or 5/2-] and 3.0 MeV (Γ = 1.5 MeV) (1956SC01). Above 5 MeV, the p0 yield at 0° increases monotonically with energy to E(3He) = 17 MeV (1965FL03). Polarization measurements are reported at E(3He) = 1.4 to 2.0 MeV (1966SI1C, 1971SI1J; p0, p1). See also (1970GA1G) and 8Be.
The yields of 0.43 and 0.48 MeV γ-rays (reaction (c)), measured for E(3He) = 0.5 to 1.3 MeV, are reported to show the excitation of 9B*(17.20 ± 0.02) with Γ = 110 ± 30 keV, Jπ = 1/2+, 3/2+; T = 1/2 (1970AL25). See also 7Be.
Excitation functions for ground state tritons (reaction (d)) have been measured for E(3He) = 10 to 16 MeV (1969NU1A) and 23.3 to 25.4 MeV (1972GI07). See also 6Be. Differential cross sections have been measured at several angles for the 3He groups to 6Li*(0, 2.19) (reaction (e)) for E(3He) = 23.3 to 25.4 MeV (1972GI07). See also 6Li.
Angular distributions at Eα = 8.0, 10.0, 12.0 and 14.0 MeV all display strong forward peaking (1963ME08). At Eα = 14.4 MeV, neutron groups are observed to 9Be*(0, 2.4): the upper limit of the cross section to a state at ≈ 1.7 MeV is 100 μb/sr or < 0.1 of the ground state group (1964BA29). See also 10B.
Angular distributions of the t0 group have been measured for E(6Li) = 4.0 to 5.5 MeV and at 7.35 and 9.0 MeV. No evidence was observed for a group corresponding to 9B*(1.6) (1966KI09).
For E(3He) to 12.5 MeV this reaction populates 9B*(0, 2.4, 2.8, (7.0)) (1963DU12) and levels at 12.06 ± 0.06 [0.8 ± 0.2], 14.01 ± 0.07 [0.39 ± 0.11], 14.670 ± 0.016 [ < 0.045], 16.024 ± 0.025 [0.180 ± 0.016], 17.19 and 17.63 MeV [widths in brackets] (1964DI1A, 1965DI03). (1967BA59) report Q = (-5306 ± 5) keV and therefore Ex = 14.659 ± 0.005 MeV (based on Qm).
9B*(14.66) is the first T = 3/2 state in 9B (1965DI03). It γ-decays to 9B*(0, 2.4, 2.8) with branching ratios which appear to be similar to those for the analog state in 9Be: see Table 9.6 (in PDF or PS). Assuming that the Γγ for both T = 3/2 states in 9Be, 9B are the same, the total Γ for 9B*(14.66) is then ≈ 80% of that for 9Be*(14.40): 260+90-120 eV (1971AD01) [corrected for revised value of Γ of 9Be*(14.40)]. The ratio Γp0/Γγ0 < 1.5, Γp1/Γγ0 = 13.9 ± 2.1 [Γp0 is the width for decay of 9B*(14.66) to the ground state of 8Be; Γp1 is that for decay to 8Be*(2.9)]. Assuming Γγ0 for 9B*(14.66) = 6.9 ± 0.5 eV [the value for the analog state in 9Be: see Table 9.6 (in PDF or PS)], Γp0 < 10 eV, Γp1 = 96 ± 20 eV (1972AD04). See also (1971AD1C).
Angular distributions have been reported for E(3He) = 1.56 to 5.27 MeV (1966DI04; n0) and 3.1 MeV (1970GU08; n0). (1970GU08) find that a structure in the neutron spectrum which might correspond to 9B*(1.5) is really due to sequential decay of 9Be*(11.8) to 8Be(0). They also report a 9B state with Ex = 4.8 ± 0.1 MeV, Γ = 1.0 ± 0.2 MeV. See also (1970LI1Q), (1969BA1Z) and 10B.
For Ed = 0.75 to 1.70 MeV, resonances in the yields of protons are observed at Ed = 0.900 ± 0.025 MeV (p0, p2.4) and 1.475 ± 0.010 MeV (p2.4 only) with Γcm = 120 ± 40 and 71 ± 8 keV, respectively [9B* = 17.19 and 17.64 MeV] (1960KA17). See (1972PA1C) for astrophysical considerations.
A high resolution experiment at Ep = 20 MeV shows the population of 9B*(0, 2.4) and is consistent with the excitation of 9B*(2.8) [Γ ≈ 0.3 MeV] and 9B*(7.0) [Γ > 1 MeV]. No other states are excited for Ex < 7.1 MeV (1970AN07). (1972AR22) report Ex = 3.09 ± 0.10 MeV. Additional states have been reported by a number of groups: see (1966LA04) for earlier references and (1967SL04, 1970CL01). The width of the ground state is 540 ± 210 eV (1964TE01).
Angular distributions have been measured at Ep = 3.5 to 10.9 MeV (1965WA04), 6.8 MeV (1967DR08), 8 to 14 MeV (1960SA03), 18.5 MeV (1964AN1B) and 30.3 and 49.3 MeV (1970CL01). See also (1967BO1D, 1969JU1A, 1969VE02, 1970WI1B, 1971BE46, 1971CA1F, 1972CA1Q, 1973WA28), (1966LA04) and (1966PA1H, 1968TH1H; theor.).
Angular distributions have been reported at E(3He) = 3.0 to 3.8 MeV (1969OR01; t0), 5.0 to 9.0 MeV (1967EA01; t0), 5.7 MeV (1959HI69; t0), 10 MeV (1967CR04; t0, t2.4), 20 to 27.8 MeV (1969OP1A, 1970OP1B; t0, t2.4) and 25 MeV (1960WE04; t0, t2.4). At E(3He) = 39.8 MeV 9Be(0) is very stongly excited and 9B*(2.4, 14.7) are also observed. There is some indication that other known 9B states are also populated (1969BA06). See also 12C in (1975AJ02) and (1970CA28).
At E(6Li) = 30.8 and 31.8 MeV the ground state of 9B is strongly excited. 9B*(2.4) is also observed (1970CH19, 1971CH1B). A partial angular distribution for the ground state transition is reported at the higher energy by (1971CH1B).
Several groups of delayed protons are observed indicating the involvement of a number of 9B states: see Table 9.10 (in PDF or PS) (1972ES05). It is not possible to determine ft values since some of the 9B states involved in the 9C decay may decay via 5Li + α: see (1972ES05).
At Ep = 33.6 MeV (1968KU04, 1970KU1D) and 155.6 MeV (1969BA05) deuteron groups are observed to 9B*(0, 2.4, 7.0, 11.7, 14.7). All have angular distributions characteristic of ln = 1 and therefore odd parity and J = (3/2, 5/2, 7/2, 9/2): see Table 9.11 (in PDF or PS). There is some evidence also for the population of 9B*(2.8, 18.4) (1968KU04, 1969BA05). Angular distributions have also been reported at Ep = 49.5 MeV (1970SQ01; d0, d2.4, d11.7). See also (1968KR02), (1966LA04) and (1969TO1A; theor.).
Angular distributions have been measured at Ed = 11.8 MeV (1966BA21, 1967FI07; t0, t2.4) [S for 9B*(0, 2.4) = 0.80 and 0.64, respectively], 13.5 MeV (1964FU15; t0) and 28 MeV [(1968GA13; t0); (1971IN1C; t0, t2.4 (partial)]. See also (1971WA1K, 1972WA1M) and (1966BA1X, 1971BO50; theor.).
Alpha particle spectra show the excitation of 9B*(0, 2.4, 2.8, 11.8): see (1966LA04). Measurements by (1968KR02) determine Ex = 2.361 ± 0.005 and 2.788 ± 0.030 MeV, Γ = 81 ± 5 and 548 ± 40 keV, respectively [see Table 9.11 (in PDF or PS) in (1966LA04) for other values]. There is some evidence for a state with Ex ≈ 1.6 MeV, Γ ≈ 0.7 MeV, but it is not conclusive, in agreement with the older work [see (1960SP08, 1962BA1C)]. No evidence is found for any narrow levels in 9B with Γ ≤ 100 keV and 4 < Ex < 7 MeV: the upper limit to the intensity of the corresponding α-group is 1% of the intensity of the group to 9B*(2.4) (1968KR02). Angular distributions have been determined at E(3He) = 5.5 MeV (1966CA02; α0) and 33.7 MeV (1971SQ03; α0, α2.4, α11.8). DWBA does not seem to give a good description of the transition to 9B*(11.8) (1971SQ03).
In reaction (b) study of the decays of 9B*(2.4, 2.8) shows that 9B*(2.4) decays < 0.5% by proton emission to 8Be(0) [θ2f < 5.1 x 10-3] [it decays to 5Li(0) by α-emission] while the second state, Ex = 2.71 ± 0.03 MeV [Γ = 0.71 ± 0.06 MeV] decays almost 100% by that channel [θ2d = 0.74] (1966WI08). (1966WA16) find Γ = 1.1 ± 0.2 MeV for 9B*(2.8) and suggest J = 1/2 for this state [see, however, (1960SP08)]. No other excited states of 9B with 3.5 < Ex < 9.5 MeV decay by proton emission to 8Be(0) (1968KR02). See also (1970BE1F, 1971FO1E) and (1968TA1M; theor.). See also 8Be, and 13N in (1976AJ04).
At Ep = 45 MeV angular distributions have been obtained for the triton groups to 9B*(0, 2.36, 12.06, 14.01, 14.66, 16.02). In addition the spectra show some indication of the groups corresponding to 9B*(7.0, 17.19, 17.63). New T = 1/2 states are reported at Ex = 15.29 ± 0.04 and 15.58 ± 0.04 MeV (1971HA10). See also (1971KA04; theor.) and reaction 41 in 9Be.
Angular distributions of ground state α-particles have been measured at Ep = 14.0 to 17.2 MeV (1969KO1D), 19.1 to 44 MeV (1967AC01, 1969GA03, 1970GU06, 1971GU23), 38.5, 41.6 and 44.5 MeV [also partial back-angle measurements at Ep = 30.5, 32.0, 33.0, 34.5 and 39.5 MeV] (1966CR05, 1967CR05, 1968LI1E) and at Ep = 54.1 MeV (1972MA21). Alpha groups are also observed to 9B*(2.3, 2.9 ± 0.2, 6.97 ± 0.06): see (1955RE16, 1962MA40, 1964BA29, 1972MA21). See also (1966LA04). The angular distribution to 9B*(6.97) is consistent with Jπ = 7/2-; Γ ≈ 2 MeV (1972MA21: Ep = 54.1 MeV). For reaction (b) see (1972MA62) and (1966LA04). See also 12C in (1975AJ02) and 13N in (1976AJ04).
Angular distributions of 6Li ions have been obtained at E(3He) = 28 MeV (1971KL1E), 30.0 and 40.7 MeV (1972OH01) and 35.7 MeV (1969ZE1A, 1970FO1D).