KNOCKOUT REACTIONS NEUTRON KiiOCKOUT REACTIONS

M Ahmad, R Madey, J Watson, N Chant, P Roos, D Devins, D Friesel, B Flanders
unpublished
We performed the first neutron knockout measurements at IUCF in July 1980 when we studied the 1 2 0 0 1 1-r-1 I I I I I (p,pn) reaction on 4 0 ~ a and 4 8 ~ a at 150 MeV. These 4 0 ~ a (p. p n) 3 9 ~ e 1 I 1 5 0 MeV 0, = 44.3-.en=-36.15. measurements were performed in the QDDM spectrometer I 2S112 V) 8 0 0 hall with a small scattering chamber installed at an I-I I I intermediate focus on the beam line that goes into the 0 d3/2 d5/2 I swinger hall; the swinger system was used as a beam dump. The
more » ... as a beam dump. The proton detector telescope consisted of a 2 mm silicon surface-barrier AE detector plus a 10 mm and 0 a 15 nrm intrinsic germanium detector. Neutron energies 0 1 0 2 0 3 0 4 0 were measured by the time-of-flight method. Two 20 in S E P A R A T I O N ENERGY (M e V) x 40 in x 4 in mean-timed NE-102 plastic-scintillation Figure 1. Separation-ener spectrum for the neutron detectors were used in a 40 in x 40 in array neutron-knockout reaction fBCa(p, pnlggCa at 150 MeV, for ep=44" and 0 , 3 3 6 '. which was placed 19 m from the target at a fixed angle of 36' (near the QDDM spectrometer). Using this flight-I T-I l-path, we obtained both the solid angle (2.86 m s r) and 150 MeV the energy resolution (-1 MeV) required for these measurements. Figures 1 and 2 show separation energy spectra for the 40~a(p,pn)39~a and 48~a(p,pn)47~a reactions, respectively, at 150 MeV with ep = 44' and ep = 4 7 '. In Fig. 1, the 2s112, ld512, and Id312 hole strengths 0 10 20 3 0 4 0 SEPARATION ENERGY (MeV) in 3 9 ~ a are clearly identified along with probable lp hole strength near 30 MeV. In Fig. 2, lf712, (29112 + Figure 2. Separation-energy spectrum for the neutron-ld3/2), and ld512 hole strengths are identified. The knockout reaction 48~a(p,pn)47~a at 150 MeV, for ep-47' and en=36'. overall separation-energy resolution for these measurements, combining both the proton-energy This resolution is comparable to that obtained in resolution and neutron-energy resolution for a range of medium-energy (p,2p) and (e,elp) experiments prior to proton and neutron energies, is about 1 MeV (FWHM). the recent work at the IUCF, and is a factor of five
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