The 12C(p,2p)11B Reaction at 100 MeV

Abstract

The 12C(p,2p)l1B reaction has been measured at 100 MeV in both symmetric and asymmetric geometries. Distorted wave impulse approximation calculations were used to obtain spectroscopic factors for all states of l1B below 7 MeV excitation. From these spectroscopic factors and the shapes of the measured angular correlations, it is concluded that (i) no large 1f components are present in the wavefunction of the ground state of 12C and (ii) this experiment gives no evidence for the formation of giant resonances as the intermediate step in multistep reaction processes to the 4·44 MeV (5/2-) and 6·74 MeV (7/2-) states of 11B.

Proton spectroscopic factor of the12Cground state from the12C(11B<

“…The spectroscopic factors obtained in theoretical and several experimental investigations are listed in Table II. After constraining r0 and a, our result is in agreement with those derived from the xlC(p,2p)u B [6], n B(<i,«)12C [7], and n C(d, 3 4 5 6 He)n B [11] reactions.…”

“…The FRESCO program could automatically search the poten tial parameters and the proton spectroscopic factor of the 12C ground state. For the experimental cross section <rexpt(0) with the absolute error Acr(0), the chi-square value x 2 per point is obtained by [22] [<x th(6 0 -CTexpt( 0 ) ] 2 Acr(6>)2 (6) where crth(0) is the DWBA theoretical cross section. The optimized potential parameters were obtained by fitting all of the n B + 12C elastic scattering cross sections.…”

“…Shell model calculations done by Cohen-Kurath [4] in 1967 predicted the proton spectroscopic factor of the ,2C ground state to be Si2C = 2.85. After that, several experiments were performed through nC(e,e'p)"B [5], n C(p,2p)"B [6], uB(d,n)nC [7], 12C(<7,3H e)n B [8,9], u B(3H e,t/)12C [10,11], n B(7L i,6H e)12C [12], and l2C (n B, 12C )n B [13,14] reactions. The spectro scopic factors extracted from these measurements are different from each other in the range of 1.85 and 4.1.…”

Elastic scattering and total reaction cross sections for theLi8+C12system

“…Thus, to obtain the spectroscopic factor for the 9 Be gs | 8 Li gs + p bound system, the spectroscopic factor for 12 C gs | 11 B gs + p must be known. For the ( 12 C, 11 B) vertex, the spectroscopic factor was taken to be C 2 S( 12 C gs ) = 2.33 ± 0.35, which is the average of values from ( 3 He,d) and (d, 3 He) studies [26][27][28][29][30]. By normalizing the FR-DWBA calculation to the experimental data, a spectroscopic factor of C 2 S( 9 Be gs ) = 1.10 ± 0.25 was obtained for the 9 Be gs | 8 Li gs + p bound system.…”

Cross sections for production of the 15.10-MeV and other astrophysically significant gamma-ray lines through excitation and spallation ofC12andLang1, Werntz2, Crannell3 et al. 1987Phys. Rev. C

“…The relative spectroscopic factors for knock-out of a p-state proton leaving the residual II B in the 112-(2.125),5/2-(4.445),312-(5.020), and 712-(6.743) states have been reported for 100-MeV incident protons. 54 In addition, the ratio of the cross section for exciting the 112+ (6.792) state to that of the 112-(2.125) state was estimated from the triply differential cross sections reported by Pugh et af., 55 where most of the strength going to the unresolved line centered at 6.76 MeV is due to the 1/2+. In Table IV, the relative cross sections for 6 is assumed to decrease as a power-law with energy from 30 to 50 Me V and if it is assumed that the gamma rays are emitted isotropically [this gives a lower limit to the total cross section since the differential cross section for the 12C(p,P''Y4.438) 12 C reaction is seen to be a minimum at 90 degrees in Fig.…”