ENTRY 23093 20090915 22172309300000001 SUBENT 23093001 20090915 22172309300100001 BIB 16 93 2309300100002 TITLE Measurements of neutron induced activation of concrete2309300100003 at 64.5 MeV. 2309300100004 AUTHOR (M.S.Uddin, S.Kamada, M.Hagawara, T.Itoga, M.Baba) 2309300100005 INSTITUTE (2JPNTOH) Cyclotron and Radioisotope Center (CYRIC), 2309300100006 Tohoku University. 2309300100007 REFERENCE (J,ANE,36,1133,2009) 2309300100008 #doi:10.1016/j.anucene.2009.04.014 2309300100009 REL-REF (I,,M.Baba+,J,NIM/A,428,454,1999) Details on neutron 2309300100010 source. Also in : M.Baba+, Proc. of 10th Int Symp. on 2309300100011 Neutron Dosimetry, Radiation Protection and Dosimetry, 2309300100012 126(Nos.1-4),13,2007. 2309300100013 (R,22653001,E.Kim+,J,NSE,129,209,1998) Data of 2309300100014 E.Kim+ were used to estimate peak-to-total ratio 2309300100015 individually for (n,4n),(n,5n), (n,7n) reactions. 2309300100016 (R,13753001,W.P.Abfaltere+,J,PR/C,63,044608,2001) 2309300100017 (R,13569001,R.W.Finlay+,J,PR/C,47,237,1993) 2309300100018 Total cross-sections for Bi and concrete target 2309300100019 reported by R.Finlay+ and W.Abfalterer+ were used 2309300100020 to calculate neutron beam attenuation. 2309300100021 FACILITY (CYCLO,2JPNTOH) 2309300100022 INC-SOURCE (P-LI7) Quasimonoenergetic neutrons were produced by 2309300100023 protons impinging on Li-nat-target (92.5% of Li-7) via2309300100024 Li-7(p,n) reaction. 70 MeV proton beam from K=110 MeV 2309300100025 AVF cyclotron of CYRIC. Thickness of Li plate was 2309300100026 measured to be 4.74 mm (2 MeV energy loss for 70 MeV 2309300100027 proton) using a micrometer with error less 0.05 mm. 2309300100028 1 m collimator of copper and iron. 2309300100029 Li target was surrounded by concrete and steel shield 2309300100030 to reduce background. 2309300100031 INC-SPECT Neutron spectrum consists of full-energy peak due to 2309300100032 Li-7(p,n)Be-7 reaction and smooth continuum component 2309300100033 attributable to multi-body breakup process. 2309300100034 TOF data were used for a part of continuum spectrum 2309300100035 close to peak and lower energy part was estimated 2309300100036 using formula of M.Baba+ (1999, see REL-REF). 2309300100037 Neutron spectrum is shown on Fig.2 of J,ANE,36,2009. 2309300100038 Total (peak+ continuum) flux 2.60E+6 n/cm**2/sec, 2309300100039 peak neutron fluence 1.34E+6 n/cm**2/sec. 2309300100040 Ratio of peak neutrons to total neutron yield in the 2309300100041 spectrum was found about 0.48 . 2309300100042 METHOD 1(TOF) Neutron spectrum was measured by TOF technique.2309300100043 2(ACTIV) 2.5 hr irradiation. 2309300100044 (STTA) Bi-Conc-Conc-Bi stacked samples were placed 2309300100045 250 cm from Li-target. 2309300100046 (GSPEC) Induced nuclides activity was measured 2309300100047 nondestructively using HPGe-gamma-ray spectroscopy. 2309300100048 DETECTOR 1(SCIN) Organic liquid scintillation detector NE213 of 2309300100049 14 cm diameter, 10 cm long, equipped with large dynamic2309300100050 range n-gamma discriminator. Placed at 7.65 m from 2309300100051 Li-target.NE213 detection efficiency was obtained by 2309300100052 SCINFUL-R Monte Carlo code (Meigo, 1997) with estimated2309300100053 error 10 %. 2309300100054 2(HPGE) For gamma-ray counting of three times 2 h, 5 h, 2309300100055 10 h. 2309300100056 SAMPLE Bismuth plates (9 cm diameter, 1 cm thick) sandwiched 2309300100057 ordinary concrete samples (5 cm diameter, 2 cm thick) 2309300100058 as Bi-Conc-Conc-Bi. 2309300100059 Atom density of elements in ordinary concrete is: 2309300100060 (in n/cm**3 * 10**24 units) 2309300100061 H - 1.23E-2 Ca - 3.32E-4 K - 4.41E-4 2309300100062 O - 4.38E-3 Si - 1.59E-2 C - 1.10E-4 2309300100063 Na - 9.22E-4 Al - 1.67E-3 Fe - 3.32E-4 2309300100064 ANALYSIS Activation of concrete by quasimonoenergetic neutrons 2309300100065 was measured. Activation cross sections on bismuth 2309300100066 was measured to confirm the experimental procedure. 2309300100067 Reaction rates for formation radionuclides identified 2309300100068 from the gamma-ray spectra and half-life were 2309300100069 estimated. Decay data for the investigated nuclides 2309300100070 were take from NUDAT2 : www.nndc.bnl.gov/nudat2 . 2309300100071 ADD-RES Measured radioactivity concentrations of nuclides 2309300100072 induced in concrete (peak neutron fluence 2309300100073 1.45E+9 n/cm**2C , peak neutron energy 64.5 MeV): 2309300100074 Nuclide Half-life Reaction Activity (Bq/g) 2309300100075 Na-24 14.96 hr Al-27(n,a)Na-24 6270+-107 2309300100076 Na-22 2.6 hr Al-27(n,2n+a)Na-22 66774+-3966 2309300100077 Na-23(n,2n)Na-22 2309300100078 Mn-52g 5.59 d Mn-55(n,4n)Mn-52g 34+-15 2309300100079 Mn-54 312.3 d Mn-55(n,2n)Mn-54 18423+-1044 2309300100080 Co-59(n,2t)Mn-54 2309300100081 Co-56 77.27 d Co-59(n,4n)Co-56 1293+-199 2309300100082 CORRECTION For the peak efficiency of HPGe-detector including 2309300100083 self-absorption. 2309300100084 For coincidence-sunning effect. 2309300100085 For the beam current fluctuation during irradiation. 2309300100086 For neutron beam attenuation by two processes- 2309300100087 - measuring the neutron flux by monitor reactions 2309300100088 Bi-209(n,4n), Bi-209(n,5n), Bi-209(n,7n) reported by 2309300100089 E.Kim+ from both front and rear monitors (Bi-209) and 2309300100090 - from total cross sections of Bi and concrete. 2309300100091 Neutron attenuation along samples obtained from total 2309300100092 cross-section was found about 37 % in the peak region. 2309300100093 ERR-ANALYS (ERR-S,7.,10.) Statistical uncertainty about 7 % - 10%.2309300100094 HISTORY (20090915C) M.M. 2309300100095 ENDBIB 93 0 2309300100096 NOCOMMON 0 0 2309300100097 ENDSUBENT 96 0 2309300199999 SUBENT 23093002 20090915 22172309300200001 BIB 3 4 2309300200002 REACTION (83-BI-209(N,4N)83-BI-206,,SIG) 2309300200003 REL-REF (A,22653004,E.Kim+,J,NSE,129,209,1998) 2309300200004 Ratio of present data to data of E.Kim is about 85%. 2309300200005 STATUS (TABLE) Text of J,ANE,36,1133,2009, page 1136. 2309300200006 ENDBIB 4 0 2309300200007 NOCOMMON 0 0 2309300200008 DATA 2 1 2309300200009 EN DATA 2309300200010 MEV MB 2309300200011 64.5 119.0 2309300200012 ENDDATA 3 0 2309300200013 ENDSUBENT 12 0 2309300299999 SUBENT 23093003 20090915 22172309300300001 BIB 3 4 2309300300002 REACTION (83-BI-209(N,5N)83-BI-205,,SIG) 2309300300003 REL-REF (A,22653005,E.Kim+,J,NSE,129,209,1998) 2309300300004 Ratio of present data to data of E.Kim is about 95%. 2309300300005 STATUS (TABLE) Text of J,ANE,36,1133,2009, page 1136. 2309300300006 ENDBIB 4 0 2309300300007 NOCOMMON 0 0 2309300300008 DATA 2 1 2309300300009 EN DATA 2309300300010 MEV MB 2309300300011 64.5 212.9 2309300300012 ENDDATA 3 0 2309300300013 ENDSUBENT 12 0 2309300399999 SUBENT 23093004 20090915 22172309300400001 BIB 3 4 2309300400002 REACTION (83-BI-209(N,7N)83-BI-203,,SIG) 2309300400003 REL-REF (A,22653007,E.Kim+,J,NSE,129,209,1998) 2309300400004 Ratio of present data to data of E.Kim is about 96%. 2309300400005 STATUS (TABLE) Text of J,ANE,36,1133,2009, page 1136. 2309300400006 ENDBIB 4 0 2309300400007 NOCOMMON 0 0 2309300400008 DATA 2 1 2309300400009 EN DATA 2309300400010 MEV MB 2309300400011 64.5 353.0 2309300400012 ENDDATA 3 0 2309300400013 ENDSUBENT 12 0 2309300499999 ENDENTRY 4 0 2309399999999