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NSE160-123

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Nuclear Science and Engineering
ISSN: 0029-5639 (Print) 1943-748X (Online) Journal homepage: http://www.tandfonline.com/loi/unse20
Measurement of Differential Cross Section for the
64
61
Zn(n,α) Ni Reaction at 2.54, 4.00, and 5.50 MeV
Guohui Zhang, Jiaguo Zhang, Rongtai Cao, Li’an Guo, Jinxiang Chen, Yu. M.
Gledenov, M. V. Sedysheva, G. Khuukhenkhuu & P. J. Szalanski
To cite this article: Guohui Zhang, Jiaguo Zhang, Rongtai Cao, Li’an Guo, Jinxiang Chen, Yu.
M. Gledenov, M. V. Sedysheva, G. Khuukhenkhuu & P. J. Szalanski (2008) Measurement of
64
61
Differential Cross Section for the Zn(n,α) Ni Reaction at 2.54, 4.00, and 5.50 MeV, Nuclear
Science and Engineering, 160:1, 123-128, DOI: 10.13182/NSE160-123
To link to this article: http://dx.doi.org/10.13182/NSE160-123
Published online: 10 Apr 2017.
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Date: 27 October 2017, At: 04:41
NUCLEAR SCIENCE AND ENGINEERING: 160, 123–128 ~2008!
Measurement of Differential Cross Section for the
64 Zn(n,a) 61 Ni
Reaction at 2.54, 4.00, and 5.50 MeV
Guohui Zhang,* Jiaguo Zhang, Rongtai Cao, Li’an Guo, and Jinxiang Chen
Downloaded by [University of Missouri-Columbia] at 04:41 27 October 2017
Peking University, Ministry of Education and School of Physics
Key Laboratory of Heavy Ion Physics, Beijing 100871, China
Yu. M. Gledenov and M. V. Sedysheva
Joint Institute for Nuclear Research, Frank Laboratory of Neutron Physics
Dubna, 141980, Russia
G. Khuukhenkhuu
National University of Mongolia, Nuclear Research Centre, Ulaanbaatar, Mongolia
and
P. J. Szalanski
University of Łódź, Institute of Physics, Łódź, Poland
Received May 11, 2007
Accepted January 19, 2008
Abstract – By using a twin-gridded ionization chamber, differential cross-section data of the 64 Zn(n,a) 61 Ni
reaction were measured at neutron energies of 2.54, 4.00, and 5.50 MeV. The experiment was performed
at the 4.5-MV Van de Graaff accelerator of the Institute of Heavy Ion Physics, Peking University, China.
Monoenergetic neutrons of 2.54 MeV were produced through the T(p,n) 3 He reaction with a solid Ti-T
target, and those of 4.00 and 5.50 MeV were produced through the D(d,n) 3 He reaction with a deuterium
gas target. The absolute neutron flux was determined through the 238 U(n,f) reaction and a BF3 long
counter was used as the neutron flux monitor. Results of the present work are combined with our previous
data between 5.0 and 6.5 MeV and compared with other measurements and evaluations.
method is not feasible because the residual nucleus 61 Ni
is stable.
In our previous works, differential cross sections of
the 64 Zn~n, a! 61 Ni reaction were measured at 5.00, 5.7,
and 6.5 ~Ref. 2! and 5.03 and 5.95 MeV ~Ref. 3! by
using a twin-gridded ionization chamber. In the present
study, we extended our measurements to 2.54, 4.00, and
5.50 MeV to obtain the information on the near threshold
and systematic behavior of this reaction.
I. INTRODUCTION
Zinc is a reactor constituent element with a significant fraction, and its neutron cross section should be
given appropriately. However, even for the major isotope 64 Zn ~48.6% isotopic abundance!, the evaluated neutron reaction data can be found only in the JEF library 1
~JEF-2.2 and JEFF-3.10A!, and there are large discrepancies among the existing evaluations and a few measurements for the 64 Zn~n, a! 61 Ni reaction cross section.2–7
For the measurement of this cross section, the activation
II. EXPERIMENT
The experiment was performed at the 4.5-MV Van
de Graaff accelerator of Peking University, China. A solid
*E-mail: guohuizhang@pku.edu.cn
123
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124
ZHANG et al.
Ti-T target and a deuterium gas target were used as neutron sources. The thickness of the Ti-T target was
0.80 mg0cm 2. Monoenergetic neutrons were produced
through the T~ p, n! 3 He reaction with the solid target.
The energy of the accelerated protons was 3.35 MeV.
The corresponding neutron energy was 2.54, and the energy spread was 0.03 MeV. The deuterium gas target was
also used to produce neutrons through the D~d, n! 3 He
reaction. The length of the gas cell was 2.0 cm, and the
deuterium gas pressure was 2.65 to 2.80 atm. The cell
was separated from the vacuum tube by a 5-mm-thick
molybdenum film. The energies of the accelerated deuterons were 1.77 and 2.84 MeV. The corresponding neutron energies were 4.00 and 5.50 MeV, and the energy
spreads were 0.21 and 0.13 MeV, respectively.
The setup of the experiment and the structure of the
twin-gridded ionization chamber were the same as that
in Ref. 3. The shape of the electrodes of the chamber is
square, and the area is 19 ⫻ 19 cm 2. The cathode and the
anode are aluminum boards coated with tungsten layer.
The material of the grid wire is tungsten coated with
gold. The diameter and the spacing of the grid wires are
0.1 and 2.0 mm, respectively. The distances from the
cathode to the grid, grid to anode, and anode to shield
were 4.4, 2.2, and 1.1 cm, respectively. The working gas
of the ionization chamber was Kr ⫹ 2.68%CO 2 . The
pressures of the working gas were 0.90, 1.25, and 1.55 atm
for the 2.54, 4.00, and 5.50 MeV measurements, respectively. The grid of the chamber was grounded. The high
voltages for the cathode and the anode were ⫺1300 and
⫹1000 V, respectively, for the 2.54-MeV measurement;
⫺1500 and ⫹1200 V, respectively, for the 4.00-MeV
measurement; and ⫺1700 and ⫹1350 V, respectively,
for the 5.50-MeV measurement.
Two 64 Zn samples ~mass 4.05 6 0.05 mg and thickness 266.3 mg0cm 2 each! attached back-to-back to the
common cathode were used for simultaneous alpha event
measurements of forward ~0 to 90 deg! and backward
~90 to 180 deg! angles. The isotopic abundance of the
64 Zn samples was 99.4%. Each sample was vacuumevaporated on a tantalum backing 4.8 cm in diameter
and 50 mm in thickness.
The 64 Zn samples were placed at the first position of
the sample changer of the gridded chamber. Two tantalum films set back-to-back at the second position of the
sample changer were used for background measurements. The electrodes of the gridded chamber were perpendicular to the beam line.
The absolute neutron flux was determined by measuring the fission rate with a 238 U foil ~diameter 4.50 cm,
mass 7.85 6 0.10 mg, and abundance 99.999%! placed
at the third position of the sample changer. The 238 U~n, f !
cross section was taken from the ENDF0B-VII.0 library.
Two compound alpha sources were used for the adjustment of electronics and the energy calibration of the data
acquisition system. The alpha sources were placed at the
fourth position of the sample changer.
Fig. 1. Two-dimensional spectrum for forward alphaparticle measurement at En ⫽ 5.50 MeV.
Fig. 2. Alpha-particle energy spectrum for En ⫽ 5.50 MeV
~0.7 ⱕ cos uL , 0.8!.
A long counter employing a BF3 neutron counter
was used as relative neutron flux monitor. The axis of
the long counter and the center of the gridded ionization
chamber were set at 0 deg to the beam line. The distance
from the front side of the long counter to the neutron
target was ;2.9 m.
For the 2.54-MeV measurement, the distance from
the solid Ti-T target to the common cathode of the twin
chamber was 23.9 cm. The proton beam current was as
high as 9.0 mA. But, because of the small cross section
of the 64 Zn~n, a! 61 Ni reaction, the total beam time was
as long as ;56.5 h ~foreground measurement ; 26 h,
background ; 16 h, neutron flux calibration ; 14.5 h!.
For the 4.00 and 5.50-MeV measurements, the distance
from the center of the gas cell to the cathode was 18.4 cm.
NUCLEAR SCIENCE AND ENGINEERING
VOL. 160
SEP. 2008
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64
Fig. 3. The pulse-height distribution of the
fragments at En ⫽ 2.54 MeV.
Zn~n,a! 61 Ni CROSS SECTION
238 U
125
fission
Fig. 5. Differential cross sections of the first and second
groups of alpha particles in the c.m. system at En ⫽ 4.00 MeV.
The deuteron beam current was ;4.0 mA. The total beam
time for 4.00 MeV was ;24.5 h ~foreground ; 13.5 h,
background ; 4.0 h, flux calibration ; 7.0 h! and for
5.50 MeV was ;14.5 h ~foreground ; 6.5 h, background ; 3.5 h, flux calibration ; 4.5 h!.
III. RESULTS
The cathode-anode two-dimensional alpha-particle
spectrum for the forward-angle measurement at 5.50 MeV
is shown in Fig. 1. Figure 2 is the alpha-particle energy
spectrum for En ⫽ 5.50 MeV ~0.8 ⱕ cos uL , 0.9!. Two
major groups of alpha particles can be found from the
figures. The first group ~with higher energies! corresponds to three energy levels of 61 Ni, i.e., ground state,
Fig. 6. Differential cross sections of the first and second
groups of alpha particles in the c.m. system at En ⫽ 5.50 MeV.
Fig. 4. Differential cross sections of the first group of
alpha particles in the c.m. system at En ⫽ 2.54 MeV.
NUCLEAR SCIENCE AND ENGINEERING
VOL. 160
SEP. 2008
the first excited state at 67 keV, and the second excited
state at 283 keV. The second group corresponds to higher
excited states of 61 Ni at 656 and 909 keV. The yield of
alpha particles feeding to higher excited states will be
much smaller, because of Coulomb barrier effects. Therefore, the present data can be considered to provide the
total alpha production cross section if they are integrated
via energy and angle.
The pulse-height distribution of the 238 U fission fragments at En ⫽ 2.54 MeV is plotted in Fig. 3, from which
the fission counts were derived.
The measured differential cross sections for the
64 Zn~n, a
61
64 Zn~n, a
61
012 ! Ni and
34. . . ! Ni reactions ~corresponding to the first and the second group of alpha
particles, respectively! transferred to the center of mass
126
ZHANG et al.
TABLE I
Differential Cross-Section Data for the First Group
of Alpha Particles of the 64 Zn~n, a! 61 Ni Reaction
at En ⫽ 2.54 MeV in the c.m. System
Downloaded by [University of Missouri-Columbia] at 04:41 27 October 2017
First Group:
64 Zn~n, a
012 !
61 Ni
cos uc
ds0dV
~mb0sr!
Uncertainty
~%!
⫺0.904
⫺0.710
⫺0.515
⫺0.318
0.282
0.93
0.79
0.74
0.58
0.66
10.0
9.0
9.0
9.0
9.0
0.485
0.690
0.896
0.72
0.77
0.83
9.0
9.0
10.0
~c.m.! system are plotted in Figs. 4, 5, and 6. The differential cross section data are listed in Tables I, II, and III.
Although the beam time for En ⫽ 2.54 MeV was as
long as 56.5 h, there were still too few a34. . . particles to obtain the differential cross sections of the
64 Zn~n,a
61
34. . . ! Ni reaction at this energy point.
Uncertainties in Tables I, II, and III and Figs. 4, 5,
and 6 include those due to the statistics of counts ~3.3 to
5%!, the uncertainty from background subtraction ~4 to
6%!, and the uncertainty of determination of 0 and 90 deg
lines ~2 to 5%!. There are also scale errors from the
uncertainty of the atom number of the 64 Zn sample
~1.23%! and 238 U sample ~1.27%!, the uncertainty of
fission counts ~3.0 to 3.4%!, and the uncertainty of 238 U
fission cross section data ~1.0%! ~Ref. 1!.
One can see that the ratio of the counts of a012 to
a34. . . decreases as En increases. At 2.54 MeV, almost all
the events belong to the first group. At 4.00 MeV, there
are some alpha events in the second group, but still much
less than the first group. Yet, at 5.50 MeV, the secondgroup alphas outnumber the first-group alphas. The
second-group alphas are almost isotropic, while the firstgroup alphas are anisotropic. The alpha particles are 90deg symmetric at 2.54 and 4.00 MeV, while slightly
forward peaked at 5.50 MeV.
Angle-integrated cross sections for each group are
listed in Table IV. They were obtained from the differential data via the second-order Legendre polynomial
fitting. For En ⫽ 4.00 and 5.50 MeV, the sum of the two
groups leads to the total ~n, a! reaction cross section.
However, the total alpha cross section at 2.54 MeV was
derived from the total counts of alpha events, and the
second group cross section at this energy point was obtained from the subtraction of the first-group alpha cross
TABLE II
Differential Cross-Section Data for the Two Groups of Alpha Particles of the
at En ⫽ 4.00 MeV in the c.m. System
First Group:
64 Zn~n, a
012 !
61 Ni
64 Zn~n, a! 61 Ni
Second Group:
64 Zn~n, a
Reaction
34. . . !
61 Ni
cos uc
ds0dV
~mb0sr!
Uncertainty
~%!
cos uc
ds0dV
~mb0sr!
Uncertainty
~%!
⫺0.952
⫺0.856
⫺0.760
⫺0.663
⫺0.566
4.32
4.04
3.83
3.78
3.09
8.0
6.5
6.5
6.5
6.5
⫺0.952
⫺0.857
⫺0.760
⫺0.664
⫺0.567
1.58
1.56
1.52
1.55
1.45
10
9.0
9.0
9.0
9.0
⫺0.468
⫺0.370
⫺0.271
0.229
0.330
2.97
2.98
2.85
2.69
2.91
6.5
6.5
6.5
6.5
6.5
⫺0.469
⫺0.371
⫺0.273
0.227
0.329
1.43
1.41
1.44
1.34
1.42
9.0
9.0
9.0
9.0
9.0
0.432
0.534
0.637
0.740
0.844
2.95
3.19
3.57
3.86
3.85
6.5
6.5
6.5
6.5
6.5
0.431
0.533
0.636
0.739
0.843
1.45
1.47
1.32
1.46
1.42
9.0
9.0
9.0
9.0
9.0
0.948
4.31
8.0
0.948
1.46
NUCLEAR SCIENCE AND ENGINEERING
10
VOL. 160
SEP. 2008
64
Zn~n,a! 61 Ni CROSS SECTION
127
TABLE III
Differential Cross-Section Data for the Two Groups of Alpha Particles of the
at En ⫽ 5.50 MeV in the c.m. System
Downloaded by [University of Missouri-Columbia] at 04:41 27 October 2017
First Group:
64 Zn~n, a
012 !
61 Ni
64 Zn~n, a! 61 Ni
Second Group:
64 Zn~n, a
Reaction
34. . . !
61 Ni
cos uc
ds0dV
~mb0sr!
Uncertainty
~%!
cos uc
ds0dV
~mb0sr!
Uncertainty
~%!
⫺0.952
⫺0.857
⫺0.761
⫺0.664
⫺0.567
2.82
2.52
2.38
2.44
2.28
8.0
6.5
6.5
6.5
6.5
⫺0.952
⫺0.857
⫺0.761
⫺0.665
⫺0.568
3.16
3.21
3.16
3.24
3.36
8.0
6.5
6.5
6.5
6.5
⫺0.469
⫺0.371
⫺0.273
0.227
0.328
2.38
1.98
1.96
2.10
2.22
6.5
7.0
7.0
7.2
7.0
⫺0.470
⫺0.372
⫺0.274
0.226
0.327
3.16
3.13
2.99
3.02
3.13
6.5
6.5
6.5
6.5
6.5
0.430
0.533
0.636
0.739
0.843
2.37
2.87
3.07
3.04
3.36
7.0
6.5
6.5
6.5
6.5
0.429
0.532
0.635
0.739
0.843
2.94
3.33
3.06
3.34
3.30
6.5
6.5
6.5
6.5
6.5
0.948
3.41
8.0
0.947
3.15
8.5
TABLE IV
Angle-Integrated Cross Sections for the 64 Zn~n, a012 ! 61 Ni,
64 Zn~n, a
61
64 Zn~n, a! 61 Ni Reactions
34. . . ! Ni, and
s ~mb!
En
~MeV!
2.54
4.00
5.50
First Group:
61
012 ! Ni
64 Zn~n, a
9.1 6 0.9
41.5 6 3.3
31.0 6 2.5
Second Group:
61
34. . . ! Ni
64 Zn~n, a
2.7 6 1.4
18.1 6 1.4
39.5 6 3.1
Total:
64 Zn~n, a! 61 Ni
11.8 6 1.1
59.6 6 3.6
70.5 6 4.0
section from the total alpha cross section. This is the
reason for the larger uncertainty of the second-group
cross section at 2.54 MeV. In Fig. 7, the present cross
sections are compared with existing data.
The present result at 5.50 MeV is very close to our
previous data around 5 MeV, which indicates the reproducibility of the experiments. They are much larger that
the data by Chen et al.5 around 5 MeV. The present data
at 2.54 MeV is much smaller than that by Gledenov et al.4
around 2 MeV, but is consistent with the newer evaluation of JEFF-3.10A. In summary, the present experiment
provides new data for the differential and total alphaproduction cross section on the 64 Zn~n, a! 61 Ni reaction,
which provide systematic information on the energy deNUCLEAR SCIENCE AND ENGINEERING
VOL. 160
SEP. 2008
Fig. 7. Present cross sections of the
tion compared with existing data.
64
Zn~n, a! 61 Ni reac-
pendence and angular distribution when they are combined with our previous data between 5.0 and 6.5 MeV.
ACKNOWLEDGMENTS
This project was supported by National Key Project for
Cooperation Researches on Key Issues Concerning Environment
128
ZHANG et al.
and Resources in China and Russia ~Grant 2005CB724804!,
and by National Natural Science Foundation of China ~Grant
10575006!. The authors acknowledge the crew of the 4.5-MV
Van de Graaff accelerator of Peking University for their kind
cooperation.
REFERENCES
1. Evaluated Nuclear Data File ~ENDF!, Database Version of
October 30, 2007; available on the Internet at http:00www.
nds.iaea.org0exfor0endf00.htm ~2007!.
Downloaded by [University of Missouri-Columbia] at 04:41 27 October 2017
2. J. YUAN et al., “Angular Distribution and Cross-Section
Measurements for 64 Zn~n, a! 61 Ni Reaction at 5.0, 5.7, and 6.5
MeV,” Nucl. Sci. Eng., 144, 108 ~2003!.
3. G. ZHANG et al., “Differential Cross-Section Measurement for the 64 Zn~n, a! 61 Ni Reaction at 5.03 and 5.95 MeV,”
Nucl. Sci. Eng., 156, 115 ~2007!.
4. Yu. M. GLEDENOV et al., “Study of the Fast Neutron Induced ~n, alpha! Reaction for Middle Mass Nuclei,” Proc. Int.
Conf. Nuclear Data for Science and Technology, Trieste, Italy,
May 19–24, 1997, p. 514, Italian Physical Society ~1997!.
5. Y. CHEN et al., “Angular Distribution and Cross Section
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6. J. L. CASANOVA and M. L. SANCHEZ, “Measurement of
the ~n, p!, ~n, alpha!, ~n, 2n! Cross Sections of Zn, Ga, Ge, As,
and Se For 14.1 MeV Neutrons, and ~n, p! Cross Sections Analysis,” An. Fis. Quim., 72, 186 ~1976!.
7. M. BORMANN, U. SEEBECK, W. VOIGHTS, and G.
WOELFER, “Level Densities of Some Medium Weight Nuclei
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NUCLEAR SCIENCE AND ENGINEERING
VOL. 160
SEP. 2008
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