ENTRY 21178 20080206 21932117800000001 SUBENT 21178001 20080206 21932117800100001 BIB 14 79 2117800100002 INSTITUTE (2UK HAR) 2117800100003 REFERENCE (J,JNE,1,57,195408) 2117800100004 (J,JNE,5,41,1957) See revised Harwell boron 2117800100005 standard in this reference. 2117800100006 (W,Egelstaff,195412) 2117800100007 (R,AERE-N/R-1131,195304) Details of data analysis. 2117800100008 AUTHOR (P.A.Egelstaff) 2117800100009 TITLE -The operation of a thermal neutron time-of-flight 2117800100010 spectrometer- 2117800100011 FACILITY (CHOPS) Slow chopper. 2117800100012 Rotating laminated Cd-Al shutter.Double-sided mirror 2117800100013 attached to shutter. P.E. cell trigger. 2117800100014 Observed gate lengths were constant to 0.5% over 2117800100015 period of 1 hour.Average motor speed was constant to 2117800100016 at least 0.5%. 2117800100017 INC-SOURCE (THCOL) Thermal column of the Bepo reactor. Collimated.2117800100018 Modified bismuth filter. 2117800100019 INC-SPECT Maxwellian distribution function was fitted to short 2117800100020 wavelength side of spectrum. Long wavelength side is 2117800100021 increased relative to short one. Discontinuity in 2117800100022 spectrum at 4 Angstrom is due to 1001-planes in 2117800100023 graphite. For neutron wavelengths > 6 Angstrom an 2117800100024 additional short length of filter material was placed 2117800100025 outside the pile shield. 2117800100026 Density spectrum is smooth Maxwellian distribution. 2117800100027 SAMPLE Gold plates of thickness 0.992,0.950,0.954 and 0.948 2117800100028 gm/cm**2. 2117800100029 METHOD (TOF) Time-of-flight. 358 cm and 204 cm path lengths. 2117800100030 (TRN) Transmissions of combinations of four gold 2117800100031 plates for measurement at energy range 0.001 eV to 2117800100032 0.1 eV. 2117800100033 Three sources of background were considered: 2117800100034 - stray neutrons coming from all directions, reduced 2117800100035 by B4C and paraffin wax shield, 2117800100036 - epi-cadmium neutrons in beam, only slightly 2117800100037 attenuated by shutter, 2117800100038 - neutrons scattered by collimating slits, shutter 2117800100039 and samples. 2117800100040 Shutter was set running at synchronous speed and all 2117800100041 pulses from detector were recorded for two-minute with2117800100042 sample in beam and then with it out. 2117800100043 Test of spectrum and counting rate at 300 micro-sec/m 2117800100044 -a. for normal condition, 2117800100045 -b. with graphite block reduced intensity by factor 2117800100046 about 15, 2117800100047 -c. with boron glass plate reduced intensity by same 2117800100048 factor, changing spectrum to give factor 4 between 2117800100049 the counting rates in first and last channels, 2117800100050 showed that various measurements agree better than 1%.2117800100051 DETECTOR (BF3) BF3 proportional counter as neutron detector. 2117800100052 7 cm diameter cylinder filled to pressure of 30 cm Hg 2117800100053 with natural BF3. 2117800100054 PART-DET (N) Neutrons. 2117800100055 ERR-ANALYS (ERR-1) Error in measured velocity from 0.5 to 0.25 % 2117800100056 due to four causes: 2117800100057 (ERR-2) motor hunting, 2117800100058 (ERR-3) error in measurement of gate length, 2117800100059 error in angular delay, 2117800100060 gate and counter triggering. 2117800100061 Uncertainty in measurement of path length was assumed 2117800100062 to be negligible. 2117800100063 (DATA-ERR) Fluctuations of measured values were mainly 2117800100064 statistical, it was established by analysis of 2117800100065 measurement on gold. 2117800100066 CORRECTION Small correction to counting rate to allow for the 2117800100067 departure from exact proportionality of counter 2117800100068 efficiency to time-of-flight. 2117800100069 Correction for shutter and air transmission. 2117800100070 For background. 2117800100071 HISTORY (19791113C) 2117800100072 (19800110E) 2117800100073 (19830412A) REL-REF added. 2117800100074 (19830429E) 2117800100075 (20080206A) M.M. Upper-lower case correction. 2117800100076 Dates were corrected for 4-digits year. 2117800100077 SUBENT .004 added as moved from 21036003. 2117800100078 SUBENT .005 was added. 2117800100079 BIB information was added. 2117800100080 REL-REF was moved into REFERENCE list. 2117800100081 ENDBIB 79 0 2117800100082 COMMON 3 3 2117800100083 ERR-1 ERR-2 ERR-3 2117800100084 PER-CENT PER-CENT PER-CENT 2117800100085 0.5 0.1 2.5 2117800100086 ENDCOMMON 3 0 2117800100087 ENDSUBENT 86 0 2117800199999 SUBENT 21178002 20080206 21932117800200001 BIB 3 5 2117800200002 REACTION (79-AU-197(N,TOT),,SIG) 2117800200003 STATUS (TABLE) Table 3 of 1-st reference contains the data 2117800200004 point at 2200 m/sec. 2117800200005 (DEP,21178004) 2117800200006 HISTORY (19791113C) 2117800200007 ENDBIB 5 0 2117800200008 NOCOMMON 0 0 2117800200009 DATA 3 1 2117800200010 EN DATA DATA-ERR 2117800200011 EV B B 2117800200012 2.5300E-02 1.0500E+02 1.0000E+00 2117800200013 ENDDATA 3 0 2117800200014 ENDSUBENT 13 0 2117800299999 SUBENT 21178003 20080206 21932117800300001 BIB 7 24 2117800300002 REACTION ((79-AU-197(N,ABS),,SIG,,,DERIV)= 2117800300003 (79-AU-197(N,G)79-AU-198,,SIG,,,DERIV)) 2117800300004 ANALYSIS From the total cross-section beyond the Bragg cut- 2117800300005 off assuming a 1/v variation in (N,ABS) and a 2117800300006 thermal inelastic cross-section of 0.3 b, and 2117800300007 taking the incoherent scattering cross-section of 2117800300008 0.4 b from Carter et.al.,Phys.Rev.,92,(1953),716. 2117800300009 ASSUMED (ASSUM1,79-AU-197(N,INL)79-AU-197,,SIG) 2117800300010 (ASSUM2,79-AU-197(N,THS)79-AU-197,INC,SIG) 2117800300011 REL-REF (R,11211001,Carter+,J,PR,92,716,1953) Reference for 2117800300012 ASSUM2. 2117800300013 CORRECTION In Text of 1-st reference, p.69 the value 97.4b is 2117800300014 given. It was revised in 2-nd reference to be 97.7b 2117800300015 (see text of 2nd reference, p.49). Small systematic 2117800300016 error in the velocity scale of slow chopper was taken 2117800300017 into account. 2117800300018 STATUS (TABLE) Table 2 of 2nd reference. 2117800300019 Text of 2-nd reference, p.49. 2117800300020 (DEP,21178002) 2117800300021 (DEP,21178004) 2117800300022 HISTORY (19791113C) 2117800300023 (20080206A) REACTION code was added "N,ABS" 2117800300024 in according to text of 1-st reference,p.69. 2117800300025 ASSUMED, CORRECTION and STATUS were added. 2117800300026 ENDBIB 24 0 2117800300027 NOCOMMON 0 0 2117800300028 DATA 5 1 2117800300029 EN DATA DATA-ERR ASSUM1 ASSUM2 2117800300030 EV B B B B 2117800300031 2.5300E-02 9.7700E+01 9.0000E-01 0.3 0.4 2117800300032 ENDDATA 3 0 2117800300033 ENDSUBENT 32 0 2117800399999 SUBENT 21178004 20080206 21932117800400001 BIB 3 8 2117800400002 REACTION (79-AU-197(N,TOT),,SIG) 2117800400003 STATUS (NDD) From NEUDADA, original data from Egelstaff, 2117800400004 December 1954. 2117800400005 Graphical data in Fig.9 of 1-st reference as the total2117800400006 cross-section dependence from neutron time of flight 2117800400007 (corresponding to energy 0.001 and 0.1 eV). 2117800400008 HISTORY (20080206T) SUBENT was moved from ENTRY 21036 2117800400009 SUBENT 003. 2117800400010 ENDBIB 8 0 2117800400011 NOCOMMON 0 0 2117800400012 DATA 3 76 2117800400013 EN DATA DATA-ERR 2117800400014 MEV B B 2117800400015 1.4200E-09 4.0400E+02 5.0000E+00 2117800400016 1.6000E-09 3.9000E+02 8.0000E+00 2117800400017 1.6600E-09 3.7200E+02 5.0000E+00 2117800400018 1.7100E-09 3.8800E+02 8.0000E+00 2117800400019 1.8000E-09 3.6400E+02 4.0000E+00 2117800400020 1.8100E-09 3.6400E+02 9.0000E+00 2117800400021 1.9400E-09 3.6100E+02 9.0000E+00 2117800400022 2.0800E-09 3.4300E+02 8.0000E+00 2117800400023 2.2400E-09 3.1700E+02 7.0000E+00 2117800400024 2.4600E-09 3.3400E+02 2.3000E+01 2117800400025 2.6000E-09 3.0600E+02 2.0000E+01 2117800400026 2.6700E-09 2.8800E+02 1.2000E+01 2117800400027 2.7900E-09 3.0400E+02 1.8000E+01 2117800400028 2.8700E-09 2.9000E+02 1.0000E+01 2117800400029 2.9900E-09 2.9000E+02 1.4000E+01 2117800400030 3.1000E-09 2.7900E+02 9.0000E+00 2117800400031 3.2300E-09 2.8900E+02 1.2000E+01 2117800400032 3.3100E-09 2.7000E+02 6.0000E+00 2117800400033 3.3400E-09 2.6800E+02 8.0000E+00 2117800400034 3.4900E-09 2.6800E+02 1.0000E+01 2117800400035 3.5300E-09 2.6200E+02 5.0000E+00 2117800400036 3.6400E-09 2.6800E+02 7.0000E+00 2117800400037 3.7200E-09 2.5000E+02 5.0000E+00 2117800400038 3.9300E-09 2.5600E+02 5.0000E+00 2117800400039 4.1500E-09 2.4300E+02 4.0000E+00 2117800400040 4.4100E-09 2.4300E+02 4.0000E+00 2117800400041 5.9600E-09 2.0500E+02 5.0000E+00 2117800400042 6.3800E-09 2.0600E+02 5.0000E+00 2117800400043 6.8600E-09 1.9800E+02 4.0000E+00 2117800400044 7.4000E-09 1.9000E+02 4.0000E+00 2117800400045 7.9900E-09 1.8000E+02 3.0000E+00 2117800400046 8.6700E-09 1.7600E+02 3.0000E+00 2117800400047 1.4900E-08 1.3520E+02 1.5000E+00 2117800400048 1.5900E-08 1.3320E+02 1.4000E+00 2117800400049 1.5900E-08 1.3320E+02 2.2000E+00 2117800400050 1.6400E-08 1.2980E+02 2.2000E+00 2117800400051 1.7200E-08 1.2490E+02 2.1000E+00 2117800400052 1.7200E-08 1.2980E+02 1.3000E+00 2117800400053 1.8000E-08 1.2340E+02 2.1000E+00 2117800400054 1.8200E-08 1.2520E+02 1.2000E+00 2117800400055 1.8500E-08 1.2090E+02 2.3000E+00 2117800400056 1.8800E-08 1.2490E+02 2.0000E+00 2117800400057 1.9600E-08 1.1700E+02 2.0000E+00 2117800400058 1.9600E-08 1.1880E+02 1.1000E+00 2117800400059 1.9600E-08 1.2480E+02 1.9000E+00 2117800400060 2.0600E-08 1.1870E+02 1.9000E+00 2117800400061 2.1300E-08 1.1620E+02 9.0000E-01 2117800400062 2.1600E-08 1.1420E+02 1.9000E+00 2117800400063 2.2300E-08 1.1070E+02 1.8000E+00 2117800400064 2.3600E-08 1.0770E+02 1.8000E+00 2117800400065 2.4100E-08 1.0690E+02 1.8000E+00 2117800400066 2.5300E-08 1.0260E+02 1.7000E+00 2117800400067 2.6600E-08 1.0510E+02 1.7000E+00 2117800400068 2.8100E-08 9.6000E+01 1.5000E+00 2117800400069 2.9600E-08 9.5500E+01 1.5000E+00 2117800400070 3.1100E-08 9.9100E+01 1.5000E+00 2117800400071 3.2100E-08 9.5300E+01 1.7000E+00 2117800400072 3.4000E-08 9.0300E+01 1.6000E+00 2117800400073 3.6000E-08 8.8400E+01 1.6000E+00 2117800400074 3.8200E-08 8.6500E+01 1.5000E+00 2117800400075 4.3200E-08 8.3000E+01 1.5000E+00 2117800400076 4.4700E-08 8.1200E+01 1.7000E+00 2117800400077 4.5800E-08 8.2300E+01 1.2000E+00 2117800400078 4.7700E-08 7.7400E+01 1.7000E+00 2117800400079 5.1500E-08 7.8100E+01 1.7000E+00 2117800400080 5.3800E-08 7.6600E+01 1.1000E+00 2117800400081 5.5200E-08 7.6000E+01 1.7000E+00 2117800400082 5.9000E-08 7.0500E+01 1.7000E+00 2117800400083 6.1000E-08 7.2700E+01 1.1000E+00 2117800400084 6.4000E-08 7.1000E+01 1.7000E+00 2117800400085 6.4500E-08 7.1400E+01 1.1000E+00 2117800400086 6.6600E-08 7.1700E+01 2.1000E+00 2117800400087 8.7600E-08 6.4700E+01 2.1000E+00 2117800400088 1.0200E-07 5.9000E+01 2.2000E+00 2117800400089 1.2000E-07 5.7300E+01 2.5000E+00 2117800400090 1.4300E-07 5.2800E+01 3.1000E+00 2117800400091 ENDDATA 78 0 2117800400092 ENDSUBENT 91 0 2117800499999 SUBENT 21178005 20080206 21932117800500001 BIB 4 6 2117800500002 REACTION (79-AU-197(N,THS)79-AU-197,,SIG,,,DERIV) 2117800500003 STATUS Text of 1-st reference, p.69. 2117800500004 (DEP,21178004) 2117800500005 ANALYSIS Intercept on the cross-section axis indicates a total 2117800500006 scattering cross-section of 9.+-2 b. 2117800500007 HISTORY (20080206C) M.M. 2117800500008 ENDBIB 6 0 2117800500009 NOCOMMON 0 0 2117800500010 DATA 3 1 2117800500011 EN DATA DATA-ERR 2117800500012 EV B B 2117800500013 0.0253 9. 2. 2117800500014 ENDDATA 3 0 2117800500015 ENDSUBENT 14 0 2117800599999 ENDENTRY 5 0 2117899999999