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Negative Pion Induced Reactions in Bismuth at 0.87 GeV
(Commemoration Issue Dedicated to Professor Takuji Yanabu
on the Occasion of his Retirement)
Nishi, Tomota; Fujiwara, Ichiro; Imanishi, Nobutsugu;
Moriyama, Hirotake; Otozai, Kiyoteru; Arakawa, Ryuichi;
Saito, Tadashi; Tsuneyoshi, Toshihiro; Takahashi, Narito;
Iwata, Shiro; Hayashi, Shigeki; Shibata, Seiichi; Kudo,
Hisaaki; Yoshida, Kunio
Bulletin of the Institute for Chemical Research, Kyoto
University (1982), 60(2): 132-139
1982-08-31
http://hdl.handle.net/2433/76985
Right
Type
Textversion
Departmental Bulletin Paper
publisher
Kyoto University
Bull. Inst. Chem.
Negative
Res., Kyoto
Pion
Univ.,
Induced
Vol. 60, No. 2, 1982
Reactions
in Bismuth
at 0.87
GeV
Tomota NISHI,*Ichiro FUJIWARA,*
Nobutsugu IMANISHI,*
Hirotake MORIYAMA,**
Kiyoteru OTOZAK***
Ryuichi ARAKAWA,****
Tadashi SAITO,****
Toshihiro TSUNEYOSHI,****
Narito TAKAHASHI,****
Shiro IwATA,*****
Shigeki HAYASHI,*****
Seiichi SHIBATA,******
Hisaaki Kup(),*******and Kunio YosIIIDA********
Received
March15, 1982
Crosssectionsof more than forty radioactiveproducts have been measuredfor the negative
pion induced reactionsin bismuthat O.87GeV. Many of the radionuclideswere measured by
direct 7-ray spectroscopyof the irradiated targets; the yieldsof the deep spallationand the binary
fissionproductswere measuredafter the radiochemicalseparations. The mass yield curve was
derivedby using the estimatedcharge dispersioncurves. Generaltrends of pioninducedreactions
such as the slope of massyieldcurve (^-,7%/amu)show a good accordance with those of the
proton induced reactions. However,the estimatedbinaryfissioncrosssection of --50 mb is considerablylowerthan that reportedfor 1GeV p+Bi.
KEY WORDS: Nuclear reaction/ 209Bi+0. 87 GeV sr-/ Charge dispersion/
Mass yield/ Spallation/ Fission/
I. INTRODUCTION
The interactions of pions with complex nuclei have been the subject of a number of
publications.1-7)Those studies, most of which concentrated on reactions with light nuclei
(A<70), have shown some different featues from the proton induced reactions, indicating
the importance of the pion-nucleon resonances. However, further studies with heavy
nuclei seem desirable, which will provide additional tests for the conclusions concerning
the difference between the pion and the proton induced reactions.
In the present study, yields of more than forty nuclides from the interactions of 0.87
GeV r- with bismuth were measured. Yield patterns deduced by constructing mass-yield
curve are compared with the other experimental and the calculated ones. Binary fission
cross section was also measured and compared with those of proton induced reactions in
Bi, Th, and U.,")
IJIM,ff—AIL ,4tM{,117N,
7EM4X, lllf
Al
g1}12-7..513, k, *E913A-,
* Institute of AtomicEnergy, KyotoUniverity,Uji, Kyoto,611.
** Faculty of Engineering
, KyotoUniversity,Kyoto 606.
*** Kobe Womens'University,Suma,Kobe 654.
****Faculty of Science,OsakaUniversity,Osaka560.
*****ResearchReactor Institute, KyotoUniversity,Kumatori,Osaka 590-04.
******Institutefor Nuclear Study, Universityof Tokyo,Tanashi,Tokyo188.
*******Faculty of Science,TokyoMetropolitanUniversity,Tokyo158.
********Institutefor SolidState Physics,Universityof Tokyo,Tokyo 106.
( 132)
ir-Induced Reaction in Bi
II. EXPERIMENTAL
Irradiations at 0. 87 GeV were carried out at the T1 line on the National Laboratory
for High Energy Physics(KEK).
Pions were produced from 8 GeV protons impinging
on a beryllium internal target. Bending and focusing magnets directed these beams to
a lead slit. The desired beam passed through the slit was once more bended in order
to reduce the background due to neutral particles and led to the targets. Beam purity
with respect to pions and noninteracting muons and electrons was measured by the use
of a Cerenkov counter, and 90% for rr- at O.87 GeV.
The targets were 40 mm diam metallic bismuth disks. The thickness is 4. 0 g cm'z.
The particle fluence was determined by the two element (12) scintillator telescope,
which is the same diam as the targets, in front of the targets. Beam intensity was about
2 x 104 sec-' for r- at 0. 87 GeV. Pion exposure durations were from ten minutes to a few
days in length to emphasize the production of residual radioactivities of varying half life.
During the longer irradiations, temporal variations in the beam intensity were recorded
and taken into consideration for the saturation values of the various activities. For the
nuclides of the shorter half life, some tens of the shorter term exposures were repeated
with the use of a pneumatic transport system and counts were accumulated to improve
statistics.
Table 1. Relevant Nuclear Properties of Measured Nuclides.12)
Nuclide
Half life
Radiation in
AbundanceNuclideHalflife Radianin
zo6Bi6.
24 d803.0.
205Bi
15.3 d1764.0.325193Hgm
2° Bi11
. 2 h984.0.
20313i11
. 8 h820.0.
niBig
1.8 h629.1.00*198Aug2.
294Pbm
66.9 in912.0.965196Aug6.
263Pb52.
1 h279.0.81194Au
201Pb
9.4 h331.0.791
200Pb
21.5 h148.0.284
199Pb90.
m367.0.648161Er
198Pb2.4
h173.0.2816'Er
/95Pb17
. m384.0.894lb°He5.
202T112
.
d440.1.00ismy8.
2007126
. 1 h1206.0.307155Dy10.2
199T17
.4 h455.0.136
198T1m
1.87 h587.0.520152Tb
198T1g5
.3 h676.0.
194T1m 32.8 m749.1.00113Ag
203Hg
46 .8 d279.0.81599Mo
'991-1gm 42 .6 m158.0.58491Sr
195Hr40
. h262.0.44
989
1961-1g69.
572
199Au3.
296/98Aum
193Au
166Tm
5 h61.0.
11. 1 h258.
13 d158.0.
2.27 d215.0.
70 d412.0.
18 d356.
39.5 h329.
15.8 h186.0.
29.6 h243.
3.24 h827.0.
29.4 h729.
h729.0.
1 h326.
h227.0.652
152Dy2.38
h257.
17.5 h344.
139Ncl=
5.5 h738.
5.3 h298.
66.7 h141.
9. 75 h556.
108
* Assumed abundance .
( 133 )
Abundance
908
0.698
394
787
947
0.88
0.5913
100
0.368
609
0.50
50
0.95
1.00*
0.69
1.00
0.0824
0.95
0.615
T. NISHI, I. FUJIWARA,N. IMANISHIet al
All countings
ment.
Induced
were
done with a Ge (Li) detector
radioactvitities
chemical
separations."'
together
with nuclear
data
peak efficiencies
of the
distributed
homogeneously
determined
by a neutron
the Kyoto
University
in the targets
The r-rays
were
of interest
system in a low-background
counted
in the spectra
used in the analysis of the
directly
and after
were summarized
experimental
data."'
environthe
radio-
in Table
The
I
photo
detector
was determined
with the known radioactive
source
in a sample as same as the targets.
The chemical yields were
activation method after the measurements
of radioactivities
at
reactor.
III. RESULT AND DISCUSSION
The absolute production
cross sections of the residual products
of O. 87 GeV 7r- with Bi are given in Table II. The uncertainties
mental
data
arise predominantly
smaller
contrbutions
arise from
from determination
corrections
for
photon
of the
photo
absorption
from the interactions
listed for the experipeak
in
peak efficiency of the detector and variations in beam intensity during
They do not include possible systematic uncertainties
in r-ray abundances.
Table II.
intensities,
the
target,
and
photo
the irradiation.
In the following
Summary of Measured Cross Sections.
NuclideYield
type*Cross
msebctionDmeteejitoip
NuclideYieldtype*CrolnsmsebctionDmeetezig
2o6BiI76
295BiI114
2o4BiI36.
20313iI33.
soiBigI19.
so.ipbmI24.
2°3PbI63.
soipbC67.
2oopbC68.
199PbC66.
199PbC45
195PbC17
292T1I16.
2ocriI
199T1I29.
198T1'C35.
199T1gC
194T1mI9.0±
2osHgI<1.
loollgmI
195HgmI
*
'
. 9 ± 4.7Ge195HggI10.
. ±11.GelosHeC29.
3± 7 .6Ge199AuI<0.
1±11. 7Ge199AumI<0
0± 3.6Ge199AugI<0
9 ± 2.4Ge196AugI<1.
8±10. 2Ge194AuI6.4±
9 ± 5.8GeiosAuC'37.
7± 11. 1Ge165TmC6.
9 ± 3.5Ge161ErC6.
. 4±18. 4GeIKE,.C4.
. 1± 6.5GewileC'2.
5 ± 2.5Ge157DyC4
21.5± 5.0GeissElyC3
0±13. 6GeloopyC2.
2 ± 5.0Ge152TbC'1.
29.0±13.6Ge139NdmI0.
2. 1GeiisAgC2.
6Ge99MoC4.
<2.3Ge91SrC1.
15.4± 5. 1Ge
0 ± 3.7Ge
9 ± 7.2Ge
7Ge
. 7Ge
.4Ge
1Ge
1.7Ge
1± 8.0Ge
7 ± 1.2
7 ± 1. 1
Chem
Chem
1±
7±
. 8±
. 7±
0±
3±
7±
2±
2±
5±
Chem
Chem
Chem
Chem
Chem
Chem
Chem
Chem
Chem
Chem
1.1
0.7
0.4
0.4
0.6
0.5
0.3
1.9
0.9
0.6
The symbols used in this column have the following meanings : "I" is the independent yields ;
"C" is the cumulative yields ; "C'" is the almost cumulative yields .
The symbols used in this column have the following meanings : "Ge" is the direct r-ray
spectroscopy ; "Chem" is the rray spectroscopy after the radiochemical separations.
( 134 )
•
7r-Induced
sections, we will discuss the interactions
1. Near target mass region
In the
near
the secondary
the effects
target
particles
mass region,
to the
of the secondary
Reaction in Bi
in three
attention
measured
particles
mass regions.
should
yields.
Unfortunately,
2 shows a smooth
to the
we
contributions
could
not
of
estimate
Since most of the secondary
however,
they
are expected
to affect
of charge dispersion curve, we obtained a curve for A=
at half maximum 4Z= 1. 60 (Fig. 1) . Assuming the same
charge dispersion curve in the near
was obtained as shown in Fig. 2.
Figure
called
such as fast neutrons.
particles have energies less than a few ten MeV,")
hardly the yields in the mass region A<203.
For the first approximation
202, 203, having the full width
be
target
trend
mass region,
of the
the
production
cross
section
cross section,
contour
decreasing
map
as the
product mass decreases.
In the mass region A>200,
the difference
(Zp—ZA) between
the most probable charge Zp and the position of 13-stability1) increases as the product
I
-o-—
>,
eII0.1—
CJ
—3
—2
I
I
I
I
A•\
—1
0
1
2
3
Z —Zp
Fig. 1.
Charge
dispersion
interaction
and open
of products,
of 0.87 GeV 7- +Bi.
points the independent
r•--
in the near target
the
produced
cumulative
by
yields
pr
-
mass region,
Filled points indicate
yields.
5
1
10
80
N
30
—0--
3
1
75
11 I 1 I I I I I I I I 1-
110115120125
N
Fig. 2. Cross section contour map in millibarn of 0.87 GeV r-+Bi. Dot-dash curve
goes through the position of the most probable charge Zp ; dashed curve the
position of p-stability Z4.14)
( 135 )
—
—
T. NISHI, I. FUJIWARA, N. IMANISHI et at
100
I
7_
•
•
2 10 e; ,1"
2
4
6
8
10 12
14
X
Fig. 3. Yields of 209Bi
pxn) at O.87GeV. The numbers on the abscissaindicate
those of emitted neutrons. Open points represent the measured independent
yields. Solid curve is drawn to aid the eye. Dashed curve, which is arbitrary
on ordinate, is taken from the stopped .7r-experiment.19)
mass decreases.
In the mass region A<200, on the other hand, (Zp —ZA) is almost
constant
5) irrespective of the product mass. This fact probably indicates that
the excitation energies of the spallation products do not depend on the product mass
sensitively.
Figure 3 shows a comparison of reaction yields from 209Bi (7c-, pxn) with O.87 GeV
7r- and stopped rc-.15 The mean numbers of emitted neutrons are
and
for O.87
GeV n and stopped 7r-, respectively. This difference is probably attributed to the different
momenta of the incident pions.
2.
Deep spallation mass region
As shown in Table II, the number of the measured isotopes is not many enough
to construct the charge dispersion curve in the mass region A--,460. However, the values
(Z—ZA) of the measured isotopes are very small compared to (Zi,—ZA) of 2.5 which
has been mentioned above. It can concludes, therefore, that the measured cumulative
yields nearly equal to the total isobaric yields. Regarding the measured cumulative yields
as the total isobaric ones, the mass yield curve was constructed as shown in Fig. 4.
The results of Monte Calro intranuclear cascade and evaporation calculation are
also shown in Fig. 4.1" 1, 000 cascades were followed and errors quoted are statistical.
From a comparison between the experimental and the predicted results, it is clear that
the prediction overstimates the production cross sections in the deep spallation mass
region and that it underestimated in the near target mass region.
The slope of the mass-yield curve for O. 87 GeV 7r- Bi is estimated to be 76/)/amu
in Fig. 4 and is compared with those of Cu spallation induced with pions, protons, and
heavy ions" in Fig. 5. The pion results are plotted at an energy corresponding to the
sum of their kinetic energy and the pion rest mass energy. It is interesting that the slope
for Bi +7r- is nearer to the of protons and heavy ions rather than to that of pions.
( 136 )
1
7r-Induced
Reaction
in Bi
4
100—
—
10 —
1
,/—
I
140
150
160
170
180
190
200
A
Fig. 4. Mass yield curve for O.87 GeV 7L- induced spallation of Bi. Solid curve is drawn
to aid the eye. Dashed curve goes through the calculated points.161
E
0
I
I I1 11111
10
I
I I 11111
\
\—\
co
tn
—
5 —
O—
E
1
I
01
Fig. 5.
3.
Binary
11111111
measured
mass region
fission
•
10
mass region
fission.
The
mass yield
yields of some isotopes
A--100,
curve
decay mode for the heavy nuclei.
For neutron
the mode of formation might be described
as
in this region
as the total isobaric
is fairly attributed
to the
( 137)
•
1111111
Slope of the mass yield curve for spallation as a function of incident particle
kinetic energy. Open point represents the result of 0.87 GeV rr+Bi. Solid curve
for Cu+ proton or heavy ion and dashed curve for Cu + 7C- are taken from Ref.71
The pion points are plotted at an energy corresponding to the sum of their kinetic
energy and the pion rest mass energy.
The binary fission is a characteristic
rich nuclides in the mass region A--100,
low-energy
I
1
Kinetic energy, GeV
is shown
yields. The
low-energy
in Fig. 6 regarding
observed
fission.
For
hump
the
in the
lack of better
T. NISHI, I. FUJIWARA, N. IMANISHI et at
40
111111111111111111
30 ——
•
20 ——
—
•
••
•
10 —
0
Fig. 6.
•
•
I I 11 I 1__sIN.1
50
100150
A. amu
10
I II
Comparison of mass yield curves in the binary fission mass region.
Open
points represent the result of 0.87 GeV re-+Bi.
Filled points are the total
isobaric yields for 28 GeV p+Th.5) Solid curve goes through those for
28 GeV p+U.8)
definition
of the
hump,
one can assume
to —100 mb or corresponds
Figure
6 shows
the
to a binary
a compariton
Gaussian
distribution.
fission cross section
of mass yield curves
This
estimated
to that
by the fissionabilities
binary
fission cross
measured
in any detail,
decreasing
section
but suggests further
is considerable
for 1 GeV p+Bi.'"
studies
The
small
However,
when
This difference
on the charge
dispersion
mass yield
from Ref.8,91 The
Bi. This trend can
as the target mass decreases.
of --50 mb
by mica tachnique
amounts
of -.-50 mb.
in this region.
curves of 28 GeV proton induced reactions in U and Th are taken
neutron rich cumulative
yields decrease in the order of U, Th, and
be explained
area
compared
is not
curve
the
known
in this region.
IV. CONCLUSION
Some conclusions
in the
in heavy
study
the
slope
(2)
yield curve show a good accordance
with those of proton;
when compared
to the prediction
of the intranuclear
cascade
however, some discordance
is observed;
and
the estimated binary
for 1 GeV p+ Bi.
target
of O. 87 GeV 7-+Bi:
general
furthermore,
that reported
of pion spallation
present
(1)
(3)
trends
can be drawn
fission cross
such
section
as
or
the
mass
evaporation,
is considerably
lower
than
ACKNOWLEDGEMENT
A part
We
of this work was done
wish to express
encouragement
assistance
our gratitude
in this work.
in the experiment.
under
the
to Professor
Thanks
are
due
Visiting
A. Kusumegi
to Mr.
We are also grateful
( 138 )
Researchers'
for
(KEK)
program
for
K. Hotta(Kyoto
the
encourgement
of KEK.
his interest
and
University)
for
provided
by
ir--Induced
professors
politan
M. Honda,
University)
S. Tanaka
(University
Reaction in Bi
of Tokyo)
and
H. Nakahara
(Tokyo
Metro-
.
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