ENTRY C1797 20170403 C166C179700000001 SUBENT C1797001 20170403 C166C179700100001 BIB 11 39 C179700100002 TITLE Excitation Functions for the Fission Isomers 240mPu C179700100003 and 239mPu from 238U(4He,xn) Reactions C179700100004 AUTHOR (M.N.Namboodiri,F.H.Ruddy,J.M.Alexander) C179700100005 REFERENCE (J,PR/C,7,(3),1222,1973) C179700100006 #doi:10.1103/PhysRevC.7.1222 C179700100007 REL-REF (O,T0129001,A.Fleury+,J,PR/C,7,1231,1973) C179700100008 INSTITUTE (1USASTB) C179700100009 FACILITY (VDGT,1USASTB) Tandem Van de Graaff Accelerator C179700100010 at Stony Brook. C179700100011 (CYCLO,1USABNL) 60-in. cyclotron at the Brookhaven C179700100012 National Laboratory (BNL). C179700100013 SAMPLE The targets consisted of natural uranium oxide C179700100014 evaporated onto a backing of nickel (1.1 mg/cm2) or C179700100015 aluminum (4.4 mg/cm2). The targets were all thicker C179700100016 than 200 microg/cm2 of U3O8 i.e., the thickness was C179700100017 greater than the recoil ranges of the products in the C179700100018 target material. C179700100019 PART-DET (FF) C179700100020 DETECTOR (TRD) Makrofol foils weighing ~0.75 mg/cm2 were used C179700100021 as detectors. C179700100022 METHOD (EXTB,REC) Spontaneously fissioning nuclei that C179700100023 recoil away from the target undergo fission either in C179700100024 flight or after being stopped by the catcher placed C179700100025 downstream. Fission fragments recoiling backward are C179700100026 detected by dielectric track detectors placed on the C179700100027 target cover plate. In the irradiations at Stony C179700100028 Brook, the beam was collimated (2.2-mm diam) and was C179700100029 allowed to hit the target placed in a 3.2-mm C179700100030 aperture. In the BNL experiments the collimator and C179700100031 target apertures were 4.8 and 6.4 mm, respectively. C179700100032 Energies up to 28 MeV for the 4He ions were obtained C179700100033 at Stony Brook, and higher energies at BNL. Cross C179700100034 sections for the formation of isomers were calculated C179700100035 at each bombarding energy. The effective target C179700100036 thickness was assumed to be equal to the recoil range C179700100037 of the reaction products in the target material (U3O8).C179700100038 Radial fragment distributions were used to deduced C179700100039 half lives of fission isomers. C179700100040 HISTORY (20170403C) BP C179700100041 ENDBIB 39 0 C179700100042 COMMON 1 3 C179700100043 ERR-SYS C179700100044 PER-CENT C179700100045 20.0 C179700100046 ENDCOMMON 3 0 C179700100047 ENDSUBENT 46 0 C179700199999 SUBENT C1797002 20170403 C166C179700200001 BIB 4 9 C179700200002 REACTION (92-U-238(A,2N)94-PU-240-L1,,SIG) C179700200003 DECAY-DATA (94-PU-240-L1,2.4NSEC) Fission isomer, half-life of C179700200004 2.4+-0.5 nsec measured by authors. C179700200005 ERR-ANALYS (ERR-T) Computed cross section uncertainties from C179700200006 the statistical uncertainty in the number of C179700200007 tracks observed and the 20% systematic uncertainty C179700200008 (ERR-SYS) 20% over-all uncertainty which includes C179700200009 estimated errors in beam monitoring. C179700200010 STATUS (TABLE) Table II, page 1227. C179700200011 ENDBIB 9 0 C179700200012 COMMON 1 3 C179700200013 ERR-HL C179700200014 NSEC C179700200015 0.5 C179700200016 ENDCOMMON 3 0 C179700200017 DATA 4 24 C179700200018 EN DATA ERR-T DATA-MAX C179700200019 MEV MICRO-B MICRO-B MICRO-B C179700200020 20.0 0.12 C179700200021 20.5 0.6 0.2 C179700200022 21.3 1.7 0.5 C179700200023 21.9 3.0 0.6 C179700200024 22.1 6.4 1.2 C179700200025 22.4 8.2 1.8 C179700200026 22.6 9.4 2.4 C179700200027 22.8 8.2 1.8 C179700200028 23.4 9.5 2.0 C179700200029 23.8 12.0 2.5 C179700200030 25.3 8.9 1.8 C179700200031 26.0 8.4 1.8 C179700200032 26.2 7.4 1.5 C179700200033 26.8 6.4 1.5 C179700200034 27.2 5.1 1.1 C179700200035 28.3 3.4 0.8 C179700200036 29.1 3.5 0.9 C179700200037 30.0 1.8 0.5 C179700200038 32.4 0.8 0.3 C179700200039 33.0 1.0 0.4 C179700200040 33.5 2.9 0.7 C179700200041 34.6 1.3 0.4 C179700200042 35.9 1.6 0.5 C179700200043 37.4 1.9 0.6 C179700200044 ENDDATA 26 0 C179700200045 ENDSUBENT 44 0 C179700299999 SUBENT C1797003 20170403 C166C179700300001 BIB 3 4 C179700300002 REACTION (92-U-238(A,2N)94-PU-240-L2,,SIG) C179700300003 DECAY-DATA (94-PU-240-L2,29.NSEC) T1/2=29 nsec fission isomer C179700300004 data, unobserved in the present experiment. C179700300005 STATUS (TABLE) Table III, page 1228. C179700300006 ENDBIB 4 0 C179700300007 NOCOMMON 0 0 C179700300008 DATA 2 4 C179700300009 EN DATA-MAX C179700300010 MEV MICRO-B C179700300011 21.9 0.05 C179700300012 23.4 0.28 C179700300013 25.3 0.18 C179700300014 26.0 0.14 C179700300015 ENDDATA 6 0 C179700300016 ENDSUBENT 15 0 C179700399999 SUBENT C1797004 20170403 C166C179700400001 BIB 5 10 C179700400002 REACTION (92-U-238(A,3N)94-PU-239-L,,SIG) C179700400003 DECAY-DATA (94-PU-239-L,8.MICROSEC) C179700400004 ERR-ANALYS (ERR-T) Computed cross section uncertainties from C179700400005 the statistical uncertainty in the number of C179700400006 tracks observed and the 20% systematic uncertainty C179700400007 (ERR-SYS) 20% over-all uncertainty which includes C179700400008 estimated errors in beam monitoring. C179700400009 FLAG (1.) The target-to-detector distance was 9.5 mm C179700400010 compared to 0.8 mm for the other experiments. C179700400011 STATUS (TABLE) Table IV, page 1228. C179700400012 ENDBIB 10 0 C179700400013 NOCOMMON 0 0 C179700400014 DATA 5 16 C179700400015 EN DATA-MAX DATA ERR-T FLAG C179700400016 MEV MICRO-B MICRO-B MICRO-B NO-DIM C179700400017 24.3 1.5 0.6 1. C179700400018 24.8 2.6 1.0 1. C179700400019 25.8 3.2 1.8 1. C179700400020 26.8 3.1 1.5 1. C179700400021 27.2 3.3 1.0 C179700400022 28.3 8.1 1.9 C179700400023 29.1 11.6 2.6 C179700400024 30.0 10.9 3.2 C179700400025 32.0 21.8 5.0 C179700400026 32.4 16.6 3.5 C179700400027 33.0 16.9 4.2 C179700400028 33.5 26.0 5.4 C179700400029 34.6 13.0 2.7 C179700400030 35.9 11.1 2.5 C179700400031 37.4 10.0 2.2 C179700400032 45.3 8.0 2.4 C179700400033 ENDDATA 18 0 C179700400034 ENDSUBENT 33 0 C179700499999 SUBENT C1797005 20170403 C166C179700500001 BIB 4 6 C179700500002 REACTION (92-U-238(A,4N)94-PU-238-L1,,SIG) C179700500003 DECAY-DATA (94-PU-238-L1,6.5NSEC) C179700500004 ANALYSIS Entire short-lived component assigned as 6.5-nsec C179700500005 fission isomer in 238mPu; isomer was unobserved in C179700500006 the present experiment. C179700500007 STATUS (TABLE) Table V, page 1229. C179700500008 ENDBIB 6 0 C179700500009 NOCOMMON 0 0 C179700500010 DATA 2 5 C179700500011 EN DATA-MAX C179700500012 MEV MICRO-B C179700500013 33.0 0.24 C179700500014 33.5 0.65 C179700500015 34.6 0.47 C179700500016 35.9 0.42 C179700500017 37.4 0.64 C179700500018 ENDDATA 7 0 C179700500019 ENDSUBENT 18 0 C179700599999 SUBENT C1797006 20170403 C166C179700600001 BIB 4 6 C179700600002 REACTION (92-U-238(A,4N)94-PU-238-L2,,SIG) C179700600003 DECAY-DATA (94-PU-238-L2,0.9NSEC) C179700600004 ANALYSIS Result for 0.9 nsec component when resolving C179700600005 short-lived component into 0.9 -nsec fission and 6.6 C179700600006 nsec components. C179700600007 STATUS (TABLE) Table VI, page 1229. C179700600008 ENDBIB 6 0 C179700600009 NOCOMMON 0 0 C179700600010 DATA 2 5 C179700600011 EN DATA-MAX C179700600012 MEV MICRO-B C179700600013 33.0 34.0 C179700600014 33.5 33.0 C179700600015 34.6 30.0 C179700600016 35.9 10.0 C179700600017 37.4 36.0 C179700600018 ENDDATA 7 0 C179700600019 ENDSUBENT 18 0 C179700699999 SUBENT C1797007 20170403 C166C179700700001 BIB 4 6 C179700700002 REACTION (92-U-238(A,4N)94-PU-238-L1,,SIG) C179700700003 DECAY-DATA (94-PU-238-L1,6.5NSEC) C179700700004 ANALYSIS Result for 6.5 nsec component when resolving C179700700005 short-lived component into 0.9-nsec fission and 6.6- C179700700006 nsec components. C179700700007 STATUS (TABLE) Table VI, page 1229. C179700700008 ENDBIB 6 0 C179700700009 NOCOMMON 0 0 C179700700010 DATA 2 5 C179700700011 EN DATA-MAX C179700700012 MEV MICRO-B C179700700013 33.0 0.18 C179700700014 33.5 0.45 C179700700015 34.6 0.35 C179700700016 35.9 0.38 C179700700017 37.4 0.43 C179700700018 ENDDATA 7 0 C179700700019 ENDSUBENT 18 0 C179700799999 ENDENTRY 7 0 C179799999999