ENTRY 14568 20190715 14561456800000001 SUBENT 14568001 20190715 14561456800100001 BIB 11 40 1456800100002 TITLE Measurement of the neutron capture cross section on 1456800100003 argon 1456800100004 AUTHOR (V.Fischer,L.Pagani,L.Pickard,A.Couture,S.Gardiner, 1456800100005 C.Grant,J.He,T.Johnson,E.Pantic,C.Prokop,R.Svoboda, 1456800100006 J.Ullmann,J.Wang) 1456800100007 REFERENCE (J,PR/D,99,103021,2019) 1456800100008 #doi:10.1103/PhysRevD.99.103021 1456800100009 INSTITUTE (1USADAV,1USALAS,1USABST) 1456800100010 FACILITY (LINAC,1USALAS) 1456800100011 DETECTOR (BAF2) DANCE is located at the Los Alamos National 1456800100012 Laboratory. This detector is a 4pi gamma ray 1456800100013 calorimeter composed of an array of 160 BaF2 crystals, 1456800100014 each coupled to a PMT. 1456800100015 SAMPLE The target consists of a hollow aluminum cylinder (2.9 1456800100016 cm long and 3 cm in diameter) sealed by two 0.0762 mm 1456800100017 thick Kapton windows spaced apart by 2.30+-0.05 cm. 1456800100018 The target volume was filled with high purity (99.999% 1456800100019 Ar) gaseous natural argon and pressurized (T=296.7+-1K,1456800100020 p=1.0987+-0.0005 bara) above the local atmospheric 1456800100021 pressure throughout the data taking period. The target 1456800100022 is located at the center of the DANCE spectrometer. 1456800100023 METHOD (TOF) The Argon Capture Experiment at DANCE (ACED) is 1456800100024 a time-of-flight (TOF) system capable of measuring 1456800100025 neutron energy in the thermal range to an accuracy of 1456800100026 a few meV. Events in DANCE are recorded in a 15 ms 1456800100027 acquisition window, triggered by either a beam spill or1456800100028 an external pulser - provided the energy deposit is 1456800100029 >150 keV. Individual gamma rays are reconstructed via 1456800100030 a nearest neighbor clustering algorithm. The number of 1456800100031 reconstructed clusters provides the multiplicity of the1456800100032 event; the energy of each cluster provides the 1456800100033 individual reconstructed gamma energy, with the summed 1456800100034 energy yielding the total reconstructed event energy. 1456800100035 Both a total energy and a cluster multiplicity cut are 1456800100036 applied in order to select events from neutron captures1456800100037 on 40Ar. 1456800100038 MONITOR (3-LI-6(N,T)2-HE-4,,SIG) Li,He were beam monitors. 1456800100039 (2-HE-3(N,P)1-H-3,,SIG) 1456800100040 STATUS (APRVD) Approved by L.Pagani on July 17, 2019. 1456800100041 HISTORY (20190715C) BP 1456800100042 ENDBIB 40 0 1456800100043 NOCOMMON 0 0 1456800100044 ENDSUBENT 43 0 1456800199999 SUBENT 14568002 20190715 14561456800200001 BIB 3 4 1456800200002 REACTION (18-AR-40(N,G)18-AR-41,,SIG) 1456800200003 ERR-ANALYS (DATA-ERR) Total error includes statistical and 1456800200004 systematic uncertainties. 1456800200005 STATUS (TABLE) Authors' data. 1456800200006 ENDBIB 4 0 1456800200007 NOCOMMON 0 0 1456800200008 DATA 3 50 1456800200009 EN DATA DATA-ERR 1456800200010 KEV B B 1456800200011 1.4791E-05 9.2917E-01 8.1406E-02 1456800200012 1.5488E-05 8.7659E-01 7.6799E-02 1456800200013 1.6218E-05 8.6163E-01 7.5486E-02 1456800200014 1.6982E-05 8.2708E-01 7.2459E-02 1456800200015 1.7783E-05 8.1706E-01 7.1580E-02 1456800200016 1.8621E-05 8.1752E-01 7.1618E-02 1456800200017 1.9498E-05 7.9012E-01 6.9216E-02 1456800200018 2.0417E-05 7.7180E-01 6.7611E-02 1456800200019 2.1380E-05 7.6492E-01 6.7006E-02 1456800200020 2.2387E-05 7.4115E-01 6.4923E-02 1456800200021 2.3442E-05 7.2480E-01 6.3490E-02 1456800200022 2.4547E-05 6.9263E-01 6.0672E-02 1456800200023 2.5704E-05 6.9668E-01 6.1026E-02 1456800200024 2.6915E-05 6.7122E-01 5.8796E-02 1456800200025 2.8184E-05 6.7029E-01 5.8714E-02 1456800200026 2.9512E-05 6.4255E-01 5.6284E-02 1456800200027 3.0903E-05 6.3643E-01 5.5747E-02 1456800200028 3.2359E-05 6.2250E-01 5.4527E-02 1456800200029 3.3884E-05 6.0488E-01 5.2983E-02 1456800200030 3.5481E-05 5.9030E-01 5.1706E-02 1456800200031 3.7154E-05 5.8370E-01 5.1128E-02 1456800200032 3.8904E-05 5.6186E-01 4.9214E-02 1456800200033 4.0738E-05 5.4990E-01 4.8167E-02 1456800200034 4.2658E-05 5.4895E-01 4.8083E-02 1456800200035 4.4668E-05 5.4402E-01 4.7652E-02 1456800200036 4.6773E-05 5.2677E-01 4.6141E-02 1456800200037 4.8978E-05 5.1622E-01 4.5217E-02 1456800200038 5.1286E-05 4.9627E-01 4.3470E-02 1456800200039 5.3703E-05 4.7519E-01 4.1624E-02 1456800200040 5.6234E-05 4.6170E-01 4.0443E-02 1456800200041 5.8884E-05 4.5914E-01 4.0219E-02 1456800200042 6.1660E-05 4.4983E-01 3.9404E-02 1456800200043 6.4565E-05 4.4564E-01 3.9037E-02 1456800200044 6.7608E-05 4.1601E-01 3.6442E-02 1456800200045 7.0795E-05 4.2162E-01 3.6934E-02 1456800200046 7.4131E-05 4.0580E-01 3.5549E-02 1456800200047 7.7625E-05 3.9503E-01 3.4607E-02 1456800200048 8.1283E-05 3.9556E-01 3.4654E-02 1456800200049 8.5114E-05 3.8334E-01 3.3585E-02 1456800200050 8.9125E-05 3.5821E-01 3.1385E-02 1456800200051 9.3325E-05 3.6738E-01 3.2189E-02 1456800200052 9.7724E-05 3.5353E-01 3.0977E-02 1456800200053 1.0233E-04 3.4211E-01 2.9979E-02 1456800200054 1.0715E-04 3.4278E-01 3.0039E-02 1456800200055 1.1220E-04 3.2480E-01 2.8466E-02 1456800200056 1.1749E-04 3.1557E-01 2.7660E-02 1456800200057 1.2303E-04 3.1013E-01 2.7187E-02 1456800200058 1.2883E-04 3.0714E-01 2.6927E-02 1456800200059 1.3490E-04 3.0341E-01 2.6603E-02 1456800200060 1.4125E-04 2.8477E-01 2.4974E-02 1456800200061 ENDDATA 52 0 1456800200062 ENDSUBENT 61 0 1456800299999 SUBENT 14568003 20190715 14561456800300001 BIB 5 28 1456800300002 REACTION (18-AR-40(N,G)18-AR-41,,SIG,,,DERIV) 2200 m/sec value. 1456800300003 ANALYSIS The fit of the 40Ar cross section as a function of the 1456800300004 neutron velocity, in the energy range 0.01-0.15 eV, 1456800300005 using 1/v law, yields sigmamp=670+-26(stat)+-43(sys) mb1456800300006 and T=294+-36 K for the most probable cross section 1456800300007 and the temperature of the target. Correcting for the 1456800300008 average temperature of the moderator and the target, 1456800300009 =296+-36 K, yields sigma2200=673+-26(stat)+-59(sys) 1456800300010 mb for the standard thermal cross section. 1456800300011 ERR-ANALYS (ERR-S) Statistical errors. 1456800300012 (ERR-SYS) The dominant systematic uncertainties are: 1456800300013 (ERR-1) The calibration of the beam monitors 5.8% 1456800300014 - deduced from the detector stability between runs 1456800300015 3.1%, consistency between the monitors 2.1%. 1456800300016 (ERR-2) Uncertainties in 22Na calibration procedure 1456800300017 4.4%. 1456800300018 (ERR-3) The efficiency to detect the gamma cascades 1456800300019 0.9%. 1456800300020 (ERR-4) The uncertainty in the target density 0.3%. 1456800300021 (ERR-5) the uncertainty in the target length 2.2%. 1456800300022 (ERR-6) The systematic effect of the emission of IC 1456800300023 electrons was assessed using BrIcc <0.5%. 1456800300024 CORRECTION The cross section is corrected (1%), in each neutron 1456800300025 energy bin, to account for the presence of 36Ar in 1456800300026 natural argon. 38Ar is also present but its 1456800300027 contribution is negligible. 1456800300028 STATUS (DEP,14568002) 1456800300029 (TABLE) page 103021-4. 1456800300030 ENDBIB 28 0 1456800300031 COMMON 6 3 1456800300032 ERR-1 ERR-2 ERR-3 ERR-4 ERR-5 ERR-6 1456800300033 PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT PER-CENT 1456800300034 5.8 4.4 0.9 0.3 2.2 0.51456800300035 ENDCOMMON 3 0 1456800300036 DATA 4 1 1456800300037 EN DATA ERR-S ERR-SYS 1456800300038 EV MB MB MB 1456800300039 0.0253 672.8 25.9 58.9 1456800300040 ENDDATA 3 0 1456800300041 ENDSUBENT 40 0 1456800399999 ENDENTRY 3 0 1456899999999