ENTRY L0056 19970129 0000L005600000001 SUBENT L0056001 19970129 0000L005600100001 BIB 14 80 L005600100002 INSTITUTE (1USALRL,1CANSAS,1CANTOR) L005600100003 REFERENCE (J,PR/C,32,384,8508) L005600100004 AUTHOR (R.E.PYWELL,B.L.BERMAN,J.G.WOODWORTH,J.W.JURY, L005600100005 K.G.MCNEILL,N.T.THOMPSON) L005600100006 TITLE Photoneutron cross sections for 14C. L005600100007 FACILITY (LINAC,1USALRL) L005600100008 INC-SOURCE (QMPH,ARAD) Positron annihilation in flight. L005600100009 Energy resolution (FWHM) ranged from about 200 keV at L005600100010 the lowest energy (E(gamma) = 10 MeV) to around 400 L005600100011 keV at the highest energy (E(gamma) = 33 MeV). L005600100012 SAMPLE Two 14C samples used: L005600100013 - 9.22 grams of carbon enriched to 84 mass% in 14C L005600100014 (7.77 grams of 14C). L005600100015 - 84.1 grams of calcium carbonate (CaCO3), enriched to L005600100016 83 mass% 14C (9.45 grams of C14). L005600100017 Samples were packed in aluminium cylinders 3.8 cm in L005600100018 diameter. L005600100019 DETECTOR (BF3) Neutron 4pi detector, consisting of a 61-cm cube L005600100020 of paraffin containing 48 BF3 tubes arranged in four L005600100021 concentric rings of 12 tubes each. L005600100022 METHOD (EXTB,RINGR) Direct photoneutron detection. L005600100023 Ring-ratio neutron multiplicity measurement. L005600100024 ANALYSIS Photoneutrons measured from the 14C sample and from L005600100025 a sample-blank, both with and without the annihilationL005600100026 target present. After the recorded neutron events L005600100027 were corrected for pileup in the detector, neutron L005600100028 backgrounds (annihilation target removed) were L005600100029 substracted for both the positron and electron L005600100030 measurements. L005600100031 Because the energy spectrum of the annihilation-plus- L005600100032 Bremsstrahlung radiation differs from that of purely L005600100033 Bremsstrahlung photons, a measured correction was L005600100034 applied to the ion-chamber (beam monitor) response to L005600100035 normalize the electron data to the positron data. L005600100036 The normalized electron data then were substracted fromL005600100037 the positron data, leaving the neutron counts which L005600100038 result only from the annihilation radiation. L005600100039 The measured sample-blank data, normalized to equal L005600100040 photon flux, were substracted from the target data to L005600100041 give the net target results. L005600100042 After a small correction for the neutron multiplicity L005600100043 in each ring, the data were corrected for the energy- L005600100044 dependent efficiency of the neutron detector using theL005600100045 ring-ratio result for each energy. L005600100046 The data were converted to photoneutron cross sections L005600100047 by applying the measured ion-chamber response per L005600100048 photon, the known number of target nuclei in the beam L005600100049 and a small correction for the photon attenuation in L005600100050 the sample. L005600100051 A multiplicity analysis of the number of neutrons L005600100052 recordered in each beam burst allows the (gamma,n) andL005600100053 (gamma,2n) yields to be extracted simultaneously and L005600100054 independently. L005600100055 CORRECTION Corrected for; L005600100056 - pileup of counts in the detector, L005600100057 - ion-chamber response to electron and positron L005600100058 produced radiation, L005600100059 - neutron multiplicities in each ring, L005600100060 - photon attenuation in the sample. L005600100061 ERR-ANALYS (DATA-ERR2) Uncertainty in absolute cross section does L005600100062 not exceed 10%; and results mainly from normalization L005600100063 uncertainty and from uncertainty of about 5% in the L005600100064 absolute photon flux. L005600100065 COMMENT Cross sections for the emission of a single neutron L005600100066 display a very prominent resonance near 15 MeV which L005600100067 appears to decay primarily to the ground state of 13C.L005600100068 The (gamma,2n) cross section is sharply peaked at L005600100069 26 MeV and is large compared with those for 12C and L005600100070 13C. L005600100071 The integrated total photoneutron cross section up to L005600100072 36 MeV is observed to be 61% of the Thomas-Reiche- L005600100073 Kuhn sum-rule value. L005600100074 The 14C photoneutron cross sections are interpreted in L005600100075 terms of the reaction kinematics and the competition L005600100076 among the particle channels in order to provide L005600100077 information on the isospin properties of the major E1 L005600100078 states in 14C and on the validity of the weak core- L005600100079 coupling model. L005600100080 HISTORY (891207C) L005600100081 (950406A) BIB Updated L005600100082 ENDBIB 80 0 L005600100083 COMMON 1 3 L005600100084 DATA-ERR2 L005600100085 PER-CENT L005600100086 10. L005600100087 ENDCOMMON 3 0 L005600100088 ENDSUBENT 87 0 L005600199999 SUBENT L0056002 19970129 0000L005600200001 BIB 3 4 L005600200002 REACTION ((6-C-14(G,N)6-C-13,,SIG)+(6-C-14(G,N+P)5-B-12,,SIG)) L005600200003 Threshold of the reaction (gamma,n+p) is 25.71 MeV. L005600200004 ERR-ANALYS (DATA-ERR1) Statistical errors only. L005600200005 STATUS Converted from Berman compilation. L005600200006 ENDBIB 4 0 L005600200007 NOCOMMON 0 0 L005600200008 DATA 3 107 L005600200009 EN DATA DATA-ERR1 L005600200010 MEV MB MB L005600200011 8.244 0.0092 0.168 L005600200012 8.531 0.1079 0.156 L005600200013 8.818 -.1301 0.143 L005600200014 9.105 -.1317 0.133 L005600200015 9.392 0.1495 0.112 L005600200016 9.631 0.1756 0.147 L005600200017 9.822 0.4689 0.140 L005600200018 10.014 0.6350 0.137 L005600200019 10.205 0.4646 0.132 L005600200020 10.396 0.5336 0.121 L005600200021 10.539 0.6559 0.180 L005600200022 10.635 0.5607 0.177 L005600200023 10.731 0.7102 0.177 L005600200024 10.826 0.6578 0.153 L005600200025 10.922 1.0340 0.181 L005600200026 11.018 1.2980 0.195 L005600200027 11.113 2.3000 0.205 L005600200028 11.209 2.7070 0.224 L005600200029 11.304 2.5800 0.209 L005600200030 11.400 2.3120 0.203 L005600200031 11.496 1.5890 0.163 L005600200032 11.591 1.3980 0.303 L005600200033 11.687 1.3670 0.240 L005600200034 11.783 1.5060 0.184 L005600200035 11.878 1.5300 0.199 L005600200036 11.974 1.1360 0.221 L005600200037 12.069 1.5940 0.185 L005600200038 12.165 1.8260 0.190 L005600200039 12.261 1.6930 0.203 L005600200040 12.356 2.1190 0.194 L005600200041 12.452 2.5160 0.196 L005600200042 12.548 2.5100 0.221 L005600200043 12.643 2.6430 0.222 L005600200044 12.739 3.3420 0.186 L005600200045 12.835 3.5170 0.183 L005600200046 12.978 3.6930 0.144 L005600200047 13.169 3.8630 0.149 L005600200048 13.361 4.5000 0.163 L005600200049 13.552 4.9150 0.179 L005600200050 13.743 5.2820 0.168 L005600200051 13.934 5.5630 0.183 L005600200052 14.126 6.1400 0.198 L005600200053 14.317 6.2230 0.196 L005600200054 14.508 6.7930 0.206 L005600200055 14.651 7.3490 0.251 L005600200056 14.874 7.5120 0.309 L005600200057 15.034 7.7250 0.301 L005600200058 15.226 8.5360 0.375 L005600200059 15.417 8.9560 0.455 L005600200060 15.609 8.8360 0.338 L005600200061 15.801 8.2760 0.422 L005600200062 16.089 7.3610 0.306 L005600200063 16.377 7.3890 0.680 L005600200064 16.670 6.1930 0.695 L005600200065 17.054 5.8300 0.402 L005600200066 17.439 5.5440 0.483 L005600200067 17.824 5.4900 0.462 L005600200068 18.209 5.5650 0.537 L005600200069 18.594 5.0660 0.426 L005600200070 18.867 4.7180 0.501 L005600200071 19.111 3.9540 0.539 L005600200072 19.433 3.6680 0.667 L005600200073 19.816 3.1660 0.648 L005600200074 20.198 3.9680 0.802 L005600200075 20.581 3.6480 0.785 L005600200076 20.963 4.0550 0.724 L005600200077 21.346 3.2870 0.753 L005600200078 21.728 4.2490 0.780 L005600200079 22.111 3.9760 0.696 L005600200080 22.493 5.2670 0.727 L005600200081 22.876 3.6710 0.764 L005600200082 23.128 4.0700 0.620 L005600200083 23.467 4.2050 0.579 L005600200084 23.773 3.6040 0.573 L005600200085 24.023 2.6300 0.720 L005600200086 24.272 3.8090 0.602 L005600200087 24.501 4.6080 1.140 L005600200088 24.867 2.7200 0.725 L005600200089 25.347 2.4470 0.794 L005600200090 25.649 2.2530 1.454 L005600200091 26.078 2.0940 0.633 L005600200092 26.526 1.6610 0.626 L005600200093 26.882 1.0620 0.705 L005600200094 27.230 1.9880 0.528 L005600200095 27.737 1.7510 0.515 L005600200096 28.122 2.7110 0.750 L005600200097 28.507 3.2750 0.745 L005600200098 28.892 3.7790 0.774 L005600200099 29.277 3.1040 0.800 L005600200100 29.662 1.4090 0.777 L005600200101 30.047 2.5250 0.827 L005600200102 30.432 2.3150 0.858 L005600200103 30.817 2.3690 0.868 L005600200104 31.298 3.4650 0.879 L005600200105 31.586 1.7730 0.913 L005600200106 31.971 2.4210 1.234 L005600200107 32.356 1.2380 0.995 L005600200108 32.741 1.8210 0.956 L005600200109 33.126 2.3400 0.961 L005600200110 33.511 2.2180 0.935 L005600200111 33.896 1.7070 1.058 L005600200112 34.281 1.7990 1.168 L005600200113 34.666 0.3001 1.072 L005600200114 35.051 2.5700 1.106 L005600200115 35.426 2.1550 1.212 L005600200116 35.821 1.1410 1.148 L005600200117 36.206 2.2880 0.967 L005600200118 ENDDATA 109 0 L005600200119 ENDSUBENT 118 0 L005600299999 SUBENT L0056003 19970129 0000L005600300001 BIB 3 3 L005600300002 REACTION (6-C-14(G,2N)6-C-12,,SIG) L005600300003 ERR-ANALYS (DATA-ERR1) Statistical errors only. L005600300004 STATUS Converted from Berman compilation. L005600300005 ENDBIB 3 0 L005600300006 NOCOMMON 0 0 L005600300007 DATA 3 71 L005600300008 EN DATA DATA-ERR1 L005600300009 MEV MB MB L005600300010 13.169 0.0095 0.007 L005600300011 13.361 0.0095 0.010 L005600300012 13.552 0.0043 0.005 L005600300013 13.743 0.0181 0.010 L005600300014 13.934 0.0257 0.012 L005600300015 14.126 0.0362 0.015 L005600300016 14.317 0.0685 0.018 L005600300017 14.508 0.0762 0.034 L005600300018 14.651 0.1038 0.018 L005600300019 14.874 0.0972 0.027 L005600300020 15.034 0.1278 0.028 L005600300021 15.226 0.2291 0.037 L005600300022 15.417 0.2877 0.048 L005600300023 15.609 0.3026 0.037 L005600300024 15.801 0.2530 0.042 L005600300025 16.089 0.3612 0.033 L005600300026 16.377 0.3604 0.109 L005600300027 16.670 0.4228 0.074 L005600300028 17.054 0.4096 0.050 L005600300029 17.439 0.3875 0.062 L005600300030 17.824 0.6118 0.068 L005600300031 18.209 0.6534 0.082 L005600300032 18.594 0.7276 0.071 L005600300033 18.867 0.5363 0.076 L005600300034 19.111 0.5591 0.090 L005600300035 19.433 0.8534 0.123 L005600300036 19.816 1.2920 0.131 L005600300037 20.198 1.4110 0.165 L005600300038 20.581 1.4120 0.161 L005600300039 20.963 1.2300 0.153 L005600300040 21.346 1.6780 0.165 L005600300041 21.728 1.5380 0.173 L005600300042 22.111 1.5040 0.159 L005600300043 22.493 1.3000 0.172 L005600300044 22.876 1.8920 0.178 L005600300045 23.128 2.0360 0.148 L005600300046 23.467 1.7280 0.141 L005600300047 23.773 1.8460 0.133 L005600300048 24.023 1.8370 0.173 L005600300049 24.272 2.2470 0.155 L005600300050 24.501 1.9530 0.279 L005600300051 24.867 2.9040 0.178 L005600300052 25.347 4.2190 0.194 L005600300053 25.649 5.4030 0.344 L005600300054 26.078 5.7370 0.152 L005600300055 26.526 5.3580 0.161 L005600300056 26.882 4.4350 0.189 L005600300057 27.230 3.6710 0.151 L005600300058 27.737 3.3470 0.158 L005600300059 28.122 3.4730 0.239 L005600300060 28.507 3.0720 0.236 L005600300061 28.892 2.4470 0.243 L005600300062 29.277 2.5870 0.257 L005600300063 29.662 2.4440 0.250 L005600300064 30.047 1.6370 0.271 L005600300065 30.432 1.8130 0.280 L005600300066 30.817 1.5460 0.285 L005600300067 31.298 1.1930 0.290 L005600300068 31.586 1.7450 0.305 L005600300069 31.971 1.2890 0.374 L005600300070 32.356 1.0870 0.313 L005600300071 32.741 1.0050 0.320 L005600300072 33.126 0.4096 0.323 L005600300073 33.511 0.4991 0.306 L005600300074 33.896 0.9056 0.362 L005600300075 34.281 0.9472 0.401 L005600300076 34.666 1.3790 0.366 L005600300077 35.051 0.3222 0.381 L005600300078 35.426 0.3117 0.386 L005600300079 35.821 1.0380 0.397 L005600300080 36.206 -0.044 0.339 L005600300081 ENDDATA 73 0 L005600300082 ENDSUBENT 81 0 L005600399999 SUBENT L0056004 19970129 0000L005600400001 BIB 3 4 L005600400002 REACTION (6-C-14(G,X)0-NN-1,,SIG) L005600400003 The sum: (G,N)+(G,N+P)+2(G,2N). L005600400004 ERR-ANALYS (DATA-ERR1) Statistical errors only. L005600400005 STATUS Converted from Berman compilation. L005600400006 ENDBIB 4 0 L005600400007 NOCOMMON 0 0 L005600400008 DATA 3 107 L005600400009 EN DATA DATA-ERR1 L005600400010 MEV MB MB L005600400011 8.244 0.0092 0.168 L005600400012 8.531 0.1079 0.156 L005600400013 8.818 -.1301 0.143 L005600400014 9.105 -.1317 0.133 L005600400015 9.392 0.1495 0.112 L005600400016 9.631 0.1756 0.147 L005600400017 9.822 0.4689 0.140 L005600400018 10.014 0.6350 0.137 L005600400019 10.205 0.4646 0.132 L005600400020 10.396 0.5336 0.121 L005600400021 10.539 0.6559 0.180 L005600400022 10.635 0.5607 0.177 L005600400023 10.731 0.7102 0.177 L005600400024 10.826 0.6578 0.153 L005600400025 10.922 1.0340 0.181 L005600400026 11.018 1.2980 0.195 L005600400027 11.113 2.3000 0.205 L005600400028 11.209 2.7070 0.224 L005600400029 11.304 2.5800 0.209 L005600400030 11.400 2.3120 0.203 L005600400031 11.496 1.5890 0.163 L005600400032 11.591 1.3980 0.303 L005600400033 11.687 1.3670 0.240 L005600400034 11.783 1.5060 0.184 L005600400035 11.878 1.5300 0.199 L005600400036 11.974 1.1360 0.221 L005600400037 12.069 1.5940 0.185 L005600400038 12.165 1.8370 0.190 L005600400039 12.261 1.6930 0.203 L005600400040 12.356 2.1230 0.194 L005600400041 12.452 2.5160 0.196 L005600400042 12.548 2.5100 0.221 L005600400043 12.643 2.6430 0.222 L005600400044 12.739 3.3420 0.186 L005600400045 12.835 3.5170 0.183 L005600400046 12.978 3.6930 0.144 L005600400047 13.169 3.8820 0.149 L005600400048 13.361 4.5190 0.164 L005600400049 13.552 4.9240 0.179 L005600400050 13.743 5.3180 0.170 L005600400051 13.934 5.6140 0.184 L005600400052 14.126 6.2120 0.200 L005600400053 14.317 6.3600 0.199 L005600400054 14.508 6.9450 0.217 L005600400055 14.651 7.5770 0.254 L005600400056 14.874 7.7060 0.314 L005600400057 15.034 7.9810 0.306 L005600400058 15.226 8.9940 0.382 L005600400059 15.417 9.5310 0.465 L005600400060 15.609 9.4410 0.346 L005600400061 15.801 8.7820 0.431 L005600400062 16.089 8.0830 0.313 L005600400063 16.377 8.1100 0.714 L005600400064 16.670 7.0390 0.710 L005600400065 17.054 6.6490 0.414 L005600400066 17.439 6.3190 0.499 L005600400067 17.824 6.7140 0.481 L005600400068 18.209 6.8720 0.562 L005600400069 18.594 6.5210 0.449 L005600400070 18.867 5.7910 0.523 L005600400071 19.111 5.0720 0.568 L005600400072 19.433 5.3750 0.711 L005600400073 19.816 5.7500 0.699 L005600400074 20.198 6.7900 0.866 L005600400075 20.581 6.4720 0.849 L005600400076 20.963 6.5150 0.786 L005600400077 21.346 6.6430 0.822 L005600400078 21.728 7.3250 0.854 L005600400079 22.111 6.9840 0.765 L005600400080 22.493 7.8670 0.804 L005600400081 22.876 7.4550 0.843 L005600400082 23.128 8.1420 0.687 L005600400083 23.467 7.6610 0.643 L005600400084 23.773 7.2960 0.632 L005600400085 24.023 6.3040 0.799 L005600400086 24.272 8.3030 0.677 L005600400087 24.501 8.5140 1.269 L005600400088 24.867 8.5280 0.808 L005600400089 25.347 10.885 0.884 L005600400090 25.649 13.059 1.609 L005600400091 26.078 13.568 0.702 L005600400092 26.526 12.377 0.704 L005600400093 26.882 9.9320 0.800 L005600400094 27.230 9.3300 0.609 L005600400095 27.737 8.4450 0.604 L005600400096 28.122 9.6570 0.889 L005600400097 28.507 9.4190 0.881 L005600400098 28.892 8.6730 0.914 L005600400099 29.277 8.2780 0.951 L005600400100 29.662 6.2970 0.924 L005600400101 30.047 5.7990 0.988 L005600400102 30.432 5.9410 1.025 L005600400103 30.817 5.4610 1.039 L005600400104 31.298 5.8510 1.053 L005600400105 31.586 5.2630 1.098 L005600400106 31.971 4.9990 1.443 L005600400107 32.356 3.4120 1.175 L005600400108 32.741 3.8310 1.151 L005600400109 33.126 3.1590 1.159 L005600400110 33.511 3.2160 1.118 L005600400111 33.896 3.5180 1.282 L005600400112 34.281 3.6930 1.417 L005600400113 34.666 3.0580 1.299 L005600400114 35.051 3.2140 1.343 L005600400115 35.426 2.7780 1.362 L005600400116 35.821 3.2170 1.396 L005600400117 36.206 2.2010 1.181 L005600400118 ENDDATA 109 0 L005600400119 ENDSUBENT 118 0 L005600499999 SUBENT L0056005 19970129 0000L005600500001 BIB 2 3 L005600500002 REACTION (6-C-14(G,X)0-NN-1,,INT) L005600500003 The sum: (G,N)+(G,N+P)+(G,2N). L005600500004 STATUS (DEP,L0056002) Data taken from TABLE 2 in article L005600500005 ENDBIB 3 0 L005600500006 NOCOMMON 0 0 L005600500007 DATA 3 1 L005600500008 EN-MIN EN-MAX DATA L005600500009 MEV MEV MB*MEV L005600500010 8.18 30. 108. L005600500011 ENDDATA 3 0 L005600500012 ENDSUBENT 11 0 L005600599999 ENDENTRY 5 0 L005699999999