Transcript Diapositive 1

2011 Student Practice in JINR Fields of Research
NEUTRON EMISSION FROM
SPONTANEOUS FISSION
OF HEAVY ELEMENTS
Students:
RIHA Thomas
TARGA Alexandre
Supervisor:
Alexander I.
SVIRIKHIN
Flerov Laboratory of Nuclear Reactions,
JINR Dubna, 2011
Main goal of project
- Preparation of the detection system of VASSILISSA
separator for experiments aimed to investigation of
neutron properties of spontaneous fissioning heavy
nuclei
Vassilissa Separator
SHELS
Separator
Spontaneous
Fission detection
VASSILISSA
Separator
Fusion
Description of detectors
Calibration
Calibration
Spontaneous Fission
Energy
[MeV]
Energy
[MeV]
Alpha decay
6
120
E = 0,005*Nch
100
ftop
80
5.5
fbot
60
E = 0,0559*Nch + 37,318
40
abot
5
E = 0,0483*Nch+ 35,749
20
0
atop
E = 0,005*Nch
4.5
0
500
1000
number of channels
1500
900
1000
1100
number of channels
1200
Calibration
Calibration
fission fragments
fission fragments
Detector Efficiency
Count
1800
1600
Nn = 1249,8e-0,027t
R² = 0,972
1400
1200
1000
tav= 41 [μs]
800
600
400
200
0
0
20
40
60
80
time [μs]
100
120
140
Detector Efficiency
Neutron multiplicity distribution
Number of neutrons
14000
12000
10000
8000
6000
4000
2000
0
1
2
3
4
5
Number of neutrons/SF
6
7
Detector Efficiency
Detector Efficiency
Corrected neutron distribution
Number of
neutrons
1000
900
800
700
600
500
400
300
200
100
0
1
2
3
4
5
Number of neutrons/SF
6
7
Conclusion
- Neutron detection efficiency
ε = 45 %
- Average living time of neutron before
capturing in 3He-detector
tav = 41 μs
References
- J.R Dunning et al., Interations of neutrons with Matter
Phys. Rev. 48, 265-280 (1935)
- A.Foderaro, The Elements of Neutron Interaction theory
MIT Press, Cambridge, USA (1971)
- J. Martin, Physics for Radiation protection
John Wiley and sons, New York, USA (2000)
- D.C. Hoffman et al., Nucl. Phys., A502 (1989) 21-40
- E.A. Sokol et al., Phys. Instr. Meth., A400(1997) 96-100
- A.V. Yeremin et al., Phys. At. Nucl., 66(2003) 1042-1052
- A.V. Yeremin et al., Phys. Instr. Meth., A539(2005) 441-444
- A.I. Svirikhin et al., Eur. Phys. J. A 44, 393–396 (2010)
Acknowledgement
We would like to express our gratitude
to our supervisor Mr. Alexander I. SVIRIKHIN
for his attention and for his helpful discussions
and to the Vassilissa team as well.
Thank you for your attention!