Status and future planes of 16 O(n,α) 13 C reaction cross-section investigation at IPPE

Transcription

1 Status and future planes of 16 O(n,α) 13 C reaction cross-section investigation at IPPE V.Khryachkov, I.Bondarenko, V.Pronyaev, P.Prusachenko, A.Sergachev, N.Semenova, T.Khromyleva IPPE, Obninsk, Russia

2 Cross section, mb Status of 16 O(n,α) reaction experimental data to Dandy-68 -Davis-63 -Walton-57 -Seitz En, MeV

3 Cross section (mb) Evaluations for 16 O(n,α) reaction ENDF/B-VI.8 -ENDF/B-VII.0 -BROND-2.2 -JENDL-3.3 -CENDL ,5 4,0 4,5 5,0 5,5 6,0 6,5 7,0 7,5 8,0 8,5 9,0 Neutron Energy (MeV)

4 1. Target 2. Full absorption 3. Electrodes 4. Gas a-particles 5. Protons 6. Wall effect Classical spectrometer n

5 Gaseous target

6 Stop Input 1 Input 2 Experimental set up Anode Grid PA TFA R 2 h Cathode 238 U R 1 PA SA D DLA WFD PC Anode R 0 TFA

7 Pulse amplitude (channel) particle Pa Pc Fission fragment Td Tr Time (channel) Signals example Anode 90% of amplitude Cathode 10% of amplitude Cathode Anode DSP allow you to analyse: 1) Amplitude of anode pulse (P A ); 2) Amplitude of cathode pulse (P C ); 3) Time when cathode signal appear (T SC ); 4) Time when anode signal appear (T SA ); 5) Time when anode signal reach satiation (T EA ); 6) Time of charges motion in ionizing chamber T d =(T EA - T SC ); 7) Time of anode signal rise T r = (T EA - T SA ) 8) Birth place X=(D-T d *v e )

8 Drift time, channel Track vertical position determination 100 cathode T d O(n, ) 13 C Anode pulse amplitude, channel

9 dt distribution for 16 O(n,α) α-particles 600 N t dt, channel

10 Type of particle determination p Alphas

11 Rise time, channel Pulse shape discrimination 16 O(n, ) 13 C, En=7.1 MeV detector gas Kr(97%)CO 2 (3%) background particles Anode pulse amplitude, channel

12 α-particles specter 7000 N Initial spectra - Spectra after supression Anode pulse amplitude, channel

13 Advantages of the method Dead time for main and monitor channel is equally The simple response function of the spectrometer Achieved a big mass of the target A simple method for determining the mass of nonradioactive target Developed numerical methods to effectively suppress backgrounds Wall effect is absent

14 Cross section, barn Result 0,30 0,25 ENDF B VI IPPE ,20 0,15 0,10 0,05 0,00 4,5 4,8 5,1 5,4 5,7 6,0 6,3 6,6 6,9 7,2 7,5 En, MeV

15 Neutron yield, rel.un. Neutron yield, rel.un. Neutron yield, rel.un. Energy resolution fwhm (kev) Neutron source - EG-1 accelerator (d,d) reaction En=4-7 MeV 200 Neutron source: D(d,n) 3 He Ed in 1040 g/cm 2 TiD ,5 5,0 5,5 6,0 6,5 7,0 Neutron energy (MeV) En=5 MeV En=180 kev 0 4,5 5,0 5,5 6,0 6,5 7,0 7,5 8,0 Neutron energy, MeV En=6 MeV En=138 kev 0 4,5 5,0 5,5 6,0 6,5 7,0 7,5 8,0 Neutron energy, MeV En=7 MeV En=114 kev 0 4,5 5,0 5,5 6,0 6,5 7,0 7,5 8, Neutron energy, MeV

16 Cross section, barn Convoluted ENDF vs IPPE experiment 0,30 0,25 Convoluted ENDF B VII IPPE ,20 0,15 0,10 0,05 0,00 4,5 4,8 5,1 5,4 5,7 6,0 6,3 6,6 6,9 7,2 7,5 En, MeV

17 Cross section, barn Convoluted ENDF*1,8 and IPPE experiment 0,35 0,30 Convoluted (ENDF B VII)*1,8 IPPE ,25 0,20 0,15 0,10 0,05 0,00 4,5 4,8 5,1 5,4 5,7 6,0 6,3 6,6 6,9 7,2 7,5 En, MeV

18 Cross section, barn 0,6 0,5 V.Pronyaev evaluation Pronyaev Pronyaev (convoluted) IPPE experiment 0,4 0,3 0,2 0,1 0,0 4,0 4,5 5,0 5,5 6,0 6,5 7,0 7,5 En, MeV

19 Cross section, barn 0,6 0,5 Pronyaev evaluation and ENDF B VII Pronyaev ENDF B VII 0,4 0,3 0,2 0,1 0, En, MeV

20 Cross section, mb Comparison of IPPE data Dandy-68 -Davis-63 -Walton-57 -Seitz-55 -Harissop IPPE En, MeV

21 Cross section, barn Cross section, barn Cross section, barn Davis data vs new experiments 0,7 IRMM - ENDF B VI=JEFF JENDL JEF 2.2 0,6 - Zhang - Bichsel - Davis - Friesenhahn 0,5 0,4 0,3 0,2 0,1 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0 5,5 6,0 En, MeV 0,30 0,25 0,20 0,15 ENDF B VII JENDL 4 Davis IPPE 2011 Qaim Suhaimi Lippincott Frye Jr Wyman Woelfe 0,34 0,32 0,30 0,28 0,26 0,24 0,22 0,20 0,18 0,16 0,14 0,12 0,10 0,08 0,06 0,04 20 Ne(n, 0 )+ 20 Ne(n, 1 ) 0,02 4,0 4,5 5,0 5,5 6,0 6,5 7,0 10 B(n,2 +t) En, MeV Boner IPPE ,10 0,05 0, Neutron energy, MeV

22 Cross section, barn IRMM 2007 and IPPE 2009 data 0,35 IRMM+IPPE 2007 IPPE ,30 0,25 0,20 0,15 0,10 0,05 0, Neutron energy, MeV

23 Energy resolution fwhm (kev) Neutron energy spread IRMM IPPE Neutron energy, MeV

24 Cross section, barn Comparison of the IPPE 2009 and IRMM 2012 data 0,30 IPPE 2009 IRMM ,25 0,20 0,15 0,10 0,05 0, Neutron energy, MeV

25 Cross section, barn (IRMM 2007 )/(IRMM 2012 )=1,17 0,35 IRMM 2007 IRMM ,30 0,25 0,20 0,15 0,10 0,05 0, Neutron energy, MeV

26 IRMM correction d v ga D v cg - v cg 1 v v cg ga * d D v cg _ Exp v cg v cg _ Exp ' 1,105 ' 1,17???

27 U, arb.u. IPPE correction TS C TS A Tcg TS Aexp 40 T0 exp 20 T0 0 Tga Time, channel v cg v cg _ Exp ' 0,985 (IRMM correction is included!)

28 Conclusion New data was obtained for 16 O(n,α) 13 C reaction cross section. For neutron energy higher then 5,8 MeV there are big discrepancy of IPPE data and ENDF B VII. Shape of ENDF B VII excitation function is correct but normalization for high energy region is too low. Uncorrected IRMM data (before 2008) has the same level as IPPE data in all energy region. Correction which was done in IRMM is right but there are another correction the same scale with opposite sign. Davis s data is always has correct shape but absolute value at high energy can be significant shifted.

29 Plans Improvement of the experimental setup (golden electrodes, new gas pressure control system). New accelerator in 2015 (data up to 9 MeV). New digitizers. System for on line neutron specter measurement Using H(n,p) reaction as a monitor. Experiment at n-tof facility (good energy resolution; low energy neutron background is absent; energy up to 20 MeV).

30 Thank you for attention!