Neutron induced light-ion production from Iron and Bismuth at 175 ...

Swedish Physical Society
Swedish Nuclear Physics Meeting XXIX
17-18 November 2009, Örebro University, Örebro
Neutron induced light-ion production
from Iron and Bismuth at 175 MeV
Riccardo Bevilacqua 1 , S. Pomp 1 , V. Simutkin 1 , U. Tippawan 2 , P. Andersson 1 , J. Blomgren 1 ,
M. Österlund 1 , M. Hayashi 3 , S. Hirayama 3 , Y. Naito 3 , Y. Watanabe 3 , M. Tesinsky 4 ,
F.-R. LeColley 5 , N. Marie 5 , A. Hjalmarsson 6 , A. Prokofiev 6 , and A. Kolozhvari 7
1 Department of Physics and Astronomy, Uppsala University, Sweden
2 Fast Neutron Research Facility, Chiang Mai University, Thailand
3 Department of Advanced Energy Engineering Science, Kyushu University, Japan
4 Department of Nuclear and Reactor Physics, Royal Institute of Technology, Sweden
5 LPC, ENSICAEN, Université de Caen, France
6 The Svedberg Laboratory, Uppsala University, Sweden
7 Saint Petersburg State University, Russia

• Background and motivation
• Experimental Setup:
2/16 Riccardo Bevilacqua
Outline
Medley at the The Svedberg Laboratory (Uppsala)
• Accepted neutron spectrum
• Preliminary double differential cross sections
for production of protons, deuterons and tritons
• in comparison with model calculations using
TALYS-1.0 code.

3/16 Riccardo Bevilacqua
Background
MEDLEY @ the The Svedberg Laboratory (Uppsala, Sweden)
Large set of measurements of Double Differential Cross Section for
Light-ion production from: Fe, Pb, U, Si, O, C at 96 MeV PUBLISHED
2006 Upgrade of Neutron Beam Line:
now higher energy region under investigation (175 MeV)
2007 Carbon (analysis in Kyushu, some data already presented)
12 November 2008: my presentation at previous meeting (KTH)
2009 February Iron and Bismuth (this talk)
June Silicon (under analysis in Kyushu)
June Oxygen (under analysis in Chiang Mai)
November Uranium (last two weeks!, data in Caen, now)

natural Iron (92% 56 Fe)
3rd highest binding energy per nucleon
56 Fe is (even, even) but not magic!
It is also an important construction material
(why?) Iron and Bismuth
Lead 208 Double Magic
2,8,20,28,50,82,126
However: Bi 209 (83,126)
has just one proton more, and
it is mono-isotopic ( 208 Pb is not!)

5/16 Riccardo Bevilacqua
MEDLEY Setup
@ the The Svedberg Laboratory (Uppsala)
Conventional spectrometer, detects light ions: p, d, t, 3 He, α
Composed of 8 ΔE-ΔE-E telescope
• Angle: 20º -160º in step of 20º
• ΔE detector: Si surface barrier semi-conductor detector
• E detector: CsI(Tl) scintillator
• Using ΔE-ΔE-E technique for particle identification
1000 μm

6/16 Riccardo Bevilacqua
Time of Flight Cut:
Selecting peak neutrons
- 7 Li(p,n) reaction produces: peak neutrons & low-energy tail neutrons
- Peak neutrons are selected via Time of Flight measurements:
cut region was 2σ of TOF peak
- ”Negative” TOF: difference between master trigger
and RF timing signal from the cyclotron

Wrap around
7/16 Riccardo Bevilacqua
Accepted Neutron Spectrum
Includes tail neutrons
down to 80 MeV
CH2 target (C contribution subtracted
using data from C run – october 2007)

8/16 Riccardo Bevilacqua
Particle identification
& Energy calibration
1000 μm
ΔE-ΔE-E
Technique
Comparison
between
measured data
and calculated
energy losses
(SRIM code)

9/16 Riccardo Bevilacqua
Conversion to absolute Cross Sections
H(n,p) elastic peak from CH 2 target at 20 deg.
Cross section data for (n,p) taken from
NN cross section database http://gwdac.phys.gwu.edu
N: Number of counts in the (n,p) elastic peak
M: Molecular mass
t: target thickness [mg/cm 2 ]
Φ: relative neutron flux [n/cm 2 ]
Ω: solid angle from target to telescope [sr]

10/16 Riccardo Bevilacqua
What is (still) missing
1) Thick target correction: (thickness Fe: 375 μm, Bi: 511 μm)
Non-negligible energy loss AND absorption of the
produced light ions distorsion of measured spectra.
This correction has not been performed yet.
The reported results underestimate the values of the
cross sections in the low energy region
(shadowed in the graphs)
2) More statistic is available and it is currently under analysis
3) TALYS calculations are made with 175 MeV monoenergetic neutrons
while preliminary experimental results include low energy tail.

11/16
PRELIMINARY
PRELIMINARY
PRELIMINARY Cross Sections
Fe(n,xp), Fe(n,xd), Fe(n,xt)
PRELIMINARY
PRELIMINARY
PRELIMINARY
PRELIMINARY

12/16
PRELIMINARY
PRELIMINARY
PRELIMINARY Cross Sections
Fe(n,xp), Fe(n,xd), Fe(n,xt)
PRELIMINARY
PRELIMINARY
PRELIMINARY
PRELIMINARY

13/16
PRELIMINARY
PRELIMINARY
PRELIMINARY Cross Sections
Bi(n,xp), Bi(n,xd), Bi(n,xt)
PRELIMINARY
PRELIMINARY
PRELIMINARY
PRELIMINARY

14/16
PRELIMINARY
PRELIMINARY
PRELIMINARY Cross Sections
Bi(n,xp), Bi(n,xd), Bi(n,xt)
PRELIMINARY
PRELIMINARY
PRELIMINARY
PRELIMINARY

15/16 Riccardo Bevilacqua
Conclusions
We have measured light-ions production in the
interaction of 175 MeV neutrons with iron and bismuth
We presented first preliminary cross sections for p, d, t
and we compared them with calculations by TALYS-1.0
Better agreement with experimental results for proton
production, while we observe a general overestimation
for (n,xd) and (n,xt) reactions.
We need to introduce thick target correction
and to perform better TOF cut
(now tail neutrons down to 80 MeV are included)

16/16 Riccardo Bevilacqua
Acknowledgement
Swedish Radiation Safety Authority
Swedish Nuclear Fuel and Waste Management Co
Ringhals Nuclear Power Plant
(70% Vattenfall + 30% E.ON)
This work was supported by the European Commission
within the Sixth Framework Programme through
I3-EFNUDAT (EURATOM contract no. 036434).

Thank you for the attention!