1 Investigation of GeV proton-induced spallation reactions • Motivation • Experiment • PE cluster-emission • Neutron multiplicities • Inelastic reaction cross sections • Production cross sections of LCPs • Decay of hot nuclei as a function of excitation energy • Fission probability • Summary D. Hilscher, C.-M. Herbach, U. Jahnke, V.G. Tishchenko, HMI-Berlin J. Galin, B. Lott, A. Letourneau, A. Péghaire, GANIL D. Filges, F. Goldenbaum, K. Nünighoff, H. Schaal, G. Sterzenbach, FZ-Jülich L. Pienkowski, U. of Warsaw W.U. Schröder, J. Tõke, U. of Rochester D. Hilscher for the NESSI collaboration
36
Embed
1 Investigation of GeV proton-induced spallation reactions Motivation Experiment PE cluster-emission Neutron multiplicities Inelastic reaction cross sections.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
Investigation of GeV proton-induced spallation reactions
•Motivation•Experiment
•PE cluster-emission•Neutron multiplicities
•Inelastic reaction cross sections•Production cross sections of LCPs
•Decay of hot nuclei as a function of excitation energy •Fission probability
•Summary
D. Hilscher, C.-M. Herbach, U. Jahnke, V.G. Tishchenko, HMI-Berlin
J. Galin, B. Lott, A. Letourneau, A. Péghaire, GANIL
D. Filges, F. Goldenbaum, K. Nünighoff, H. Schaal, G. Sterzenbach, FZ-Jülich
L. Pienkowski, U. of Warsaw
W.U. Schröder, J. Tõke, U. of Rochester
D. Hilscher for the NESSI collaboration
2
Nuclear data for the target station of a spallation neutron source
GeV p
60 cm W, Hg, Pb
20 cm
25 n/p GeV
Window Fe .. Ta
Reaction length 18 cm (Pb) Preac = 1-exp(-z/Lreac)
Range 60 cm (1 GeV) nuclear stopping
cooling: 30 MeV/n reactor: 200 MeV/n
GeV proton induced
neutron production, multiplicity distributions
production cross sections of n, 1,2,3H, 3,4 He, 6,7 Li ... energy spectra in thin targets
excitation energy distributions of post INC residues
Validation of models/codes: LAHET, HERMES, INCL, FLUKA
Beam-induced radiation damage in window materials (Fe,Ta)
Cooler synchrotron and storage ring for protons p = 600 - 3400 MeV/c Ekin= 175 - 2600 MeV
6
NESSI detector
U. Jahnke et al., Nucl. Instr. Meth. A 508 (2003) 295C.-M. Herbach et al., Nucl. Instr. Meth. A 508 (2003) 315
BSiB: 162 detectors, particle separation of H, He, IMF, FF via TOF-E
Neutron multiplicity
7
Two step spallation reaction: INC+PE plus evaporation
ER2.5 GeV p + Au FF
()
n
n
n
p
p
n
E*GeV p
8
INC protons
Too many low energetic INC protons, cutoff should be at ~20 MeV
preliminary
9
Pre-equilibrium cluster emission
10
Relative yield of pre-equilibrium composite particle emission
preliminary
11
Production cross sections
preliminary
preliminary
preliminary
12
Coalescence model 2.5 GeV p+Au
jiij rrr
jiij ppp
2
1
cMeVfm
prpr ijij
/300336
00
Improvement of PE composite particle spectra but at the expense of INC nucleon spectra
300
A. Letourneau et al., Nucl. Phys. A 712 (2002) 133
13
Systematics of PE emission
preliminary
The yield of PE deuterons seems to depend on the N/Z ratio only and not in addition also on the nuclear size R
1.2 GeV p + X
d
t
α
3He
TT
TTTT ZN
ZNAN
/1
//
14
Systematics of PE emission
The yield of PE deuterons and tritons seems to depend on the N/Z ratio only and not in addition also on the nuclear size R
TT
TTTT ZN
ZNAN
/1
//
preliminary
15
Neutron multiplicity distributions in thin and thick targets
16
Neutron multiplicity (Z): thin targets
1.2 GeV p + ZT
17
Neutron multiplicity in thin and thick targets
Increase of Mn with target thickness due to inter nuclear cascade
thin targets
A. Letourneau et al., Nucl. Instr. Meth. B170 (2000) 299
18
Validation of HE-transport codes: Neutron multiplicity distributions
Preac probability to produce in BNB Mn neutrons/p in 5, 15, and 15 cm long Hg cylinders with a diameter of 15 cm
While for 1.2 GeV protons Mn distributions are well described by MCNPX and HERMES considerable deviations are observed at 2.5 GeV in particular with the MCNPX code
2.5 GeV p + Hg
D. Filges et al., Eur. Phys. J. A 11 (2001) 467
19
Hadron induced neutron production in thick Pb-targets
Available energy: Ep + 2mpc2
35 cm
15cm
thick target
D. Hilscher et al., Nucl. Instr. Meth. A414 (1998) 100