ENTRY 31791 20190311 31883179100000001 SUBENT 31791001 20190311 31883179100100001 BIB 13 67 3179100100002 TITLE Measurement of the 7Be(n,p) cross section at thermal 3179100100003 energy 3179100100004 AUTHOR (I.Tomandl, J.Vacik, U.Koester, L.Viererbl, 3179100100005 E.A.Maugeri, S.Heinitz, D.Schumann, M.Ayranov, 3179100100006 J.Ballof, R.Catherall, K.Chrysalidis, T.Day Goodacre, 3179100100007 D.Fedorov, V.Fedosseev, K.Johnston, B.Marsh, S.Rothe, 3179100100008 J.Schell, Ch.Seiffert) 3179100100009 INSTITUTE (3CZRUJF,2FR ILL,3CZRUJV,2SWTPSI,2ZZZCER,2GERMNZ, 3179100100010 2UK MAN,4RUSLIN,2GERUDE) 3179100100011 REFERENCE (J,PR/C,99,014612,2019) 3179100100012 #doi:10.1103/PhysRevC.99.014612 3179100100013 FACILITY (REAC,3CZRUJV) LVR-15 research reactor. 3179100100014 The thermal neutron equivalent flux of the beam 3179100100015 is 10**7 cm-2 s-1. 3179100100016 DETECTOR (SIBAR) The charged particle spectra were taken with a 3179100100017 fully depleted surface barrier detector with a 300 um 3179100100018 sensitive depth and 50 mm2 active area. 3179100100019 SAMPLE The 7Be target was fabricated using 7Be chemically 3179100100020 extracted from the cooling water of the SINQ facility 3179100100021 at PSI. After mass separation the 7Be ion beam was 3179100100022 focused loss free through a 5 mm diameter diaphragm and3179100100023 implanted into a 1.5 um thin Al foil. The beam spot had3179100100024 about 3 mm diameter. This Al foil was mounted between 3179100100025 two 1.5 mm thick Al frames, with the external 3179100100026 dimensions of 112 x 50.5 mm2. 3179100100027 6LiF standard was supplied by the Institute for 3179100100028 Reference Materials Measurements (IRMM) Geel. The 3179100100029 standard sample was prepared by magnetron sputtering as3179100100030 a 6LiF homogeneous layer with a thickness of 30.2(2) 3179100100031 um/cm2 deposited on a 1.5 um Al foil. 3179100100032 The targets were tilted by 15 degree with respect to 3179100100033 the neutron beam plane. 3179100100034 An eight-day measurement with 7Be and a three-day 3179100100035 measurement with 6LiF with a delimited area of 11 mm in3179100100036 diameter were combined. 3179100100037 The 7Be sample and the 6LiF standard were irradiated 3179100100038 with a collimated thermal neutron beam in a large 3179100100039 vacuum chamber. 3179100100040 MONITOR (3-LI-6(N,T)2-HE-4,,SIG) 3179100100041 CORRECTION Geometry correction factor (see also ERR-ANALYS) 3179100100042 was calculated to be 14.7(7)%. 3179100100043 ANALYSIS Taking into account a perfect 1/v dependence of the 3179100100044 neutron cross sections for both 6Li and 7Be up to 100 3179100100045 keV, the cross section of the 7Be(n,p0) reaction at 3179100100046 thermal energy (0.0253 eV), could be determined by 3179100100047 sig(6Li) of the 6Li(n,alpha)t reation and 1-3. 3179100100048 1. Ratio of areas of the p0 and t peaks in the 3179100100049 7Be(n,p0) and 6Li(n,alpha)t spectra. 3179100100050 2. Ratio of the neutron flux monitor values for the 3179100100051 7Be(n,p0) and 6Li(n,alpha)t measurements. 3179100100052 3. Ratio of numbers of 6Li atoms in the delimited 3179100100053 area of the 6LiF standard and an effective number 3179100100054 of the 7Be atomsin the sample. 3179100100055 4. geometry correction factor. 3179100100056 ERR-ANALYS (ERR-T) Final error includes both statistical and 3179100100057 systematic error (By author). 3179100100058 (MONIT-ERR) Li-6 thermal neutron cross section, 0.4% 3179100100059 (ERR-SYS) The systematic error incorporates followings.3179100100060 (ERR-1) Nominal value of the LiF-6 standard 3179100100061 thickness, 0.7% 3179100100062 (ERR-2) Delimited area of the standard, 3.7% 3179100100063 (ERR-3) Be-7 activity, 2% 3179100100064 (ERR-4) Distribution of the Be-7 atoms within the 3179100100065 sample spot, 0.8% 3179100100066 (ERR-5) Geometry and beam profile, 2.9% 3179100100067 STATUS (TABLE) From the main text of PhysRevC.99.014612(2019).3179100100068 HISTORY (20190311C) SO, NDS 3179100100069 ENDBIB 67 0 3179100100070 COMMON 9 6 3179100100071 EN MONIT MONIT-ERR ERR-SYS ERR-1 ERR-2 3179100100072 ERR-3 ERR-4 ERR-5 3179100100073 EV B B PER-CENT PER-CENT PER-CENT 3179100100074 PER-CENT PER-CENT PER-CENT 3179100100075 0.0253 940. 4. 0.4 0.7 3.7 3179100100076 2. 0.8 2.9 3179100100077 ENDCOMMON 6 0 3179100100078 ENDSUBENT 77 0 3179100199999 SUBENT 31791002 20190311 31883179100200001 BIB 5 18 3179100200002 REACTION (4-BE-7(N,P)3-LI-7,PAR,SIG) 3179100200003 EN-SEC (E-LVL,3-LI-7) 3179100200004 LEVEL-PROP ((1.)3-LI-7,E-LVL=0.000,SPIN=1.5,PARITY=-1.) p0 3179100200005 ((2.)3-LI-7,E-LVL=0.478,SPIN=0.5,PARITY=-1.) p1 3179100200006 ANALYSIS Combining following three data, a final value for the 3179100200007 partial cross section of the 7Be(n,p0) reaction at 3179100200008 thermal energy was obtained. 3179100200009 The main measurement: 3179100200010 43500 +/- 700(ERR-S) +/- 1700(ERR-SYS) b. 3179100200011 Two additional comparative measurements: 3179100200012 3mm of 6LiF standard 3179100200013 44900 +/- 1100(ERR-S) +/- 3500(ERR-SYS) b. 3179100200014 20mm of 6LiF standard 3179100200015 43500 +/- 700(ERR-S) +/- 1700(ERR-SYS) b. 3179100200016 COMMENT The final value combining three data for 7Be(n,p0) 3179100200017 mentioned as 43600 +/- 1600 b is typo. The value 43800 3179100200018 +/- 1400b mentioned both in last part in the main text 3179100200019 and in the abstract is correct. (confirmed by author) 3179100200020 ENDBIB 18 0 3179100200021 NOCOMMON 0 0 3179100200022 DATA 4 2 3179100200023 E-LVL DATA ERR-T LVL-FLAG 3179100200024 MEV B B NO-DIM 3179100200025 0.000 43800. 1400. 1. 3179100200026 0.478 520. 260. 2. 3179100200027 ENDDATA 4 0 3179100200028 ENDSUBENT 27 0 3179100299999 SUBENT 31791003 20190311 31883179100300001 BIB 2 4 3179100300002 REACTION (4-BE-7(N,P)3-LI-7,,SIG) 3179100300003 ANALYSIS To obtain the total cross section of the 7Be(n,p) 3179100300004 reaction at the thermal energy, the ratio of the p1 and3179100300005 p0 peak areas (p1/p0 = 0.012(6)) was used. 3179100300006 ENDBIB 4 0 3179100300007 NOCOMMON 0 0 3179100300008 DATA 2 1 3179100300009 DATA ERR-T 3179100300010 B B 3179100300011 44300. 1400. 3179100300012 ENDDATA 3 0 3179100300013 ENDSUBENT 12 0 3179100399999 ENDENTRY 3 0 3179199999999