ENTRY G0012 20060729 G013G001200000001 SUBENT G0012001 20060729 G013G001200100001 BIB 15 45 G001200100002 TITLE N-15 photoneutron cross section G001200100003 AUTHOR (A.D.Bates,R.P.Rassool,E.A.Milne,M.N.Thompson) G001200100004 INSTITUTE (3AULAML) G001200100005 REFERENCE (J,PR/C,40,(2),506,198909) G001200100006 FACILITY (BETAT) 35 MeV betatron at the University of Melbourne G001200100007 INC-SOURCE (BRST) the uncertainty in the photon energy is es- G001200100008 timated to Be about 100 keV below 20 MeV increasing G001200100009 to about 150 keV at 28 MeV. G001200100010 MONITOR the photon dose was measured using a thin-walled G001200100011 transmission ion chamber the response of which was G001200100012 intercalibrated against that of a standard replica G001200100013 NBS P2 chamber. G001200100014 SAMPLE a high-pressure nitrogen gas target (37 g.) Enriched G001200100015 to 98.9% In n-15, contained in a steel cylinder. G001200100016 DETECTOR (D4PI,BF3) a 4pi-halpern type neutron detector con- G001200100017 sisting of sixteen bf3 proportional gas counters G001200100018 arranged on two concentric rings, each of eight tubes. G001200100019 the neutron detection efficiency was determined from G001200100020 measurements using calibrated neutron sources and a G001200100021 measurement of the d(gamma,p)n reaction cross section. G001200100022 METHOD (EXTB) 37 independent yield curves were collected at G001200100023 photon energies ranging from 10 to 26.5 Mev. In the G001200100024 range from 10 to 19.5 Mev data were collected at 100 G001200100025 keV and elsewhere at 200 keV intervals. A total of 10 G001200100026 sample-out yield curves was measured. Average yield G001200100027 curves, obtained from the two data sets, allowed the G001200100028 yield curve for the N-15(gamma,xn) reaction being G001200100029 determined by subtraction. G001200100030 CORRECTION the resulting net yield curve was corrected for photon-G001200100031 monitor response and dead-time effects. G001200100032 ANALYSIS (PLA) the cross section was analyzed using the G001200100033 variable-bin-Penfold-Leiss method. The resulting G001200100034 N-15( gamma,xn) reaction cross section includes the G001200100035 N-15( gamma,n), N-15( gamma,pn) and twice the G001200100036 N-15( gamma,2n) reaction cross sections. The contribu- G001200100037 tion of the latter reaction, which was studied earlier G001200100038 by measuring the yield of annihilation gammas from the G001200100039 induced n-13 positron activity, was subtracted from theG001200100040 cross section data. G001200100041 ERR-ANALYS (ERR-S) the errors include only statistical G001200100042 uncertainties ( 8%). G001200100043 STATUS the data are from private communication corresponding G001200100044 to fig. 1A of Phys.Rev.C,vol 40,no 2,(1989),pp. 506. G001200100045 HISTORY (19920205C) HW G001200100046 (20060729A) Entry deleted. Duplication with G0008. G001200100047 ENDBIB 45 0 G001200100048 NOCOMMON 0 0 G001200100049 ENDSUBENT 48 0 G001200199999 NOSUBENT G0012002 20060729 G013G001200200001 ENDENTRY 2 0 G001299999999