Radioisotope production in target fragmentation with high-energy heavy ions at HIMAC A. YOKOYAMA*), T. MURAE, N. KINOSHITA,H. KIKUNAGA
Faculty of Science and Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan T. OHKI, M. SmGEKAWA,Y. KaSAMA'rSU, A. SHINOHARA
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 5600043, Japan S. SHmATA
National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi 263-8555, Japan T. SAITO
Radioisotope Research Center, Osaka University, Toyonaka, Osaka 560-0043, Japan In order to improve utilisation of the multitracer method, two aspects of the method were pursued in this study. The production of radioisotopes from target fragmentation of 197Aunuclei was performed with high-energetic heavy ions of 12C (180, 290, 400 MeV/u) and 4~ (290, 650 MeV/u) at HIMAC facilities. The yields of products were measured by using a thick-target-thickcatcher method and off-line y-ray spectrometry with Ge semiconductor detectors. Besides, a special apparatus for practice of the radioisotope production was designed in application of the tracers for separation of the products from target material with high efficiency and the target material and shape for the design was investigated in a trial examination. 1 Introduction Heavy-ion reactions on heavy targets in the energy range above 100 MeV/u are of much interest in view of a variety of reaction products covering a wide range of mass and charge. Most of the products from the reactions are considered to be formed via fragmentation process [1,2]. Fragmentation process of atomic nuclei with energetic ions is thus very useful for production of radioisotopes. Especially a variety of combination of high-energy heavy ions and targets makes it possible to produce simultaneously abundant nuclides that are useful in several fields such as biological, medical, and environmental sciences. In order to improve utilisation of the multitracer method, two aspects of the method were pursued in this study. Firstly, for accurate estimation of yields of the nuclides produced in the process, the compilation of the data and construction of a systematics for the process are needed. Secondly, continuous separation of the products from target material with high efficiency was tried in order to design a special apparatus for application of the tracers. *)E-mail address:
[email protected] Czechoslovak Journal of Physics, Vol. 53 (2003), Suppl. A
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Our group including the authors had been engaged in a series of experiments on target fragmentation of natcu, 93Nb, 141pr, 197Au nuclei etc. using high-energetic heavy ions of 12C (180 - 400 MeV/u), 2Ssi (290 - 800 MeV/u), and 4~ (290 - 650 MeV/u) from the HIMAC facility (Heavy Ion Medical Accelerator in Chiba) of the National Institute of Radiological Sciences, Japan. The accelerator does not supply intensity of the heavy ions sufficient for a practical production of the tracers. It is, however, utilised due to a simulation study for a future plan of RIKEN (The Institute for Physical and Chemical Research, Japan) using heavy ions of the similar bombarding energies. A part of the data has been already published elsewhere [3]. This paper reports chiefly on the target fragmentation on 197Au or natpt, the nuclei of which are so large that we could enjoy a variety of nuclides produced in the fragmentation.
2 Experimental For the yield measurement, the 197Autarget was bombarded with 12C (180, 290, and 400 MeV/u) and 4~ (290 and 650 MeV/u) ions from the HIMAC facility. The target foils of gold were sandwiched between catcher foils of aluminium or Kapton. Typical beam intensity was 0.1-0.2 particle nA (-1013 as total ions) for lZc projectile and 0.010.02 particle nA (-1012) for 4~ ions. The target foils and the catcher foils of an irradiated stack were separately assayed by ]'-ray spectrometry using Ge semiconductor detectors for identification of the product nuclides and measurement of their radioactivity. A computer code BOB [4] and decay curve analysis program were applied to the measured y-spectra in order to determine the cumulative yields of the product nuclides for each sample at the end of the bombardment. The yields were converted to cross-sections in terms of milibarns using nuclear data in ref. [5]. For the practice of multitracer production, we are planning to extract the products continuously into solution, which is circulated from an irradiation chamber to a reservoir outside the chamber. Prior to design of the apparatus, we performed a simulation experiment with a glass tube containing target material of platinum powder, and catcher material of agar. After the irradiation of the tube with lZc ions of 400 MeV/u, the agar was
Fig. 1. The observed radionuclides are depicted with gray squares in the nuclear chart, while stable nuclides and primordial radionuclides with black squares. A412
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Radioisotope production at HIMAC
heated to solution and separated from the target with a filter. The products recoiling out from the target were assayed in similar off-line 7-ray spectrometry as described above. 3 Results
and discussion
We observed 105 nuclides including nuclear isomers as fragments from the gold target. Formation cross sections of the products are listed in Table 1. The observed radionuclides are depicted with grey squares in Fig. 1. It is interesting to find some radionuclides
i
i
9
102
....
400
MoV/u
180
MeV/u
i
II
9,," 1!/l!! It/ ~,i-- ,! 9
/
101
~-~j~..~
,,: i
e.)
10(
50
I EPAXII
100 150 Product mass number
200
Fig.2. Mass distributions of the target fragmentation of gold at the total energy of 2.2GeV (180MeV/u) and 4.8GeV (400MeV/u). The data are compared with the systematics of EPAX II. 102
i
120~
~
;2 9 0 ~ ~ .~ 101
o
10~ 0
,
,
100
,
200
,~
P r o d u c t Mass / u
Fig.3. Recoil yields of the products from Pt powder in a simulation examination. The yields were derived from the extracted radioactivities to the total. Czech J. Phys. 53 (2003)
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Table 1. Formation cross sections in mb for the Au-197 target with C-12 or Ar-40 projectile.
Nuclide Half-Life Ar 41 K 43 Sc 46 Sc 47 Sc 48 V 48 Cr 51 Mn52 Co 55 Co 56 Fe 59 Ni 56 Zn 65 Ga 66 Ga 67 Zn 69 As 71 Zn 72 Ga 72 As 72 Se 75 Br 76 Br 77 Kr 79 Rb 81 Rb 82 Rb 83 Sr 85 Y 86 Y 87 Y 88 Zr 89 Nb 90 Nb 96 Mo93 Tc 94
g
g
m
g g g g m g g g g g m g
1.83 H 22.3 H 83.83D 3.34 D 43.7 H 15.97D 27.7 D 5.59 D 17.53 H 77.1 D 44.5 D 6.1D 244.1 D 9.49 H 3.26 D 56.4M 2.7 D 46.5 H 14.1 H 26 H 119.8 D 16.2 H 2.38D 35.04H 4.58 H 6.47H 86.2 D 64.84D 14.74H 3.35D 106.6D 3.27D 14.6H 23.35 H 6.85H 4.88 H
180 MeV/u C-12 8.54 • 7.51 •
0.97 0.86 0.88 0.48 0.73 2.42
0.61 0.35
• 0.03 • 0.13 • 0.10 • 0.08 • 0.05 • 0.09
3.52 • 0.28 2.28 • 0.70
400MeV/u C-12 7.50 •
0.45
3.32 • 0.99 • 1.65 •
0.12 0.19 0.08
3.60 •
0.19
7.38 •
0.52
290MeV/u Ar-40 19.45 • 22.7 + 15.18 • 6.12 • 6.92 •
14.5 • 2.57 2.49 1.06 4.69 6.43 5.48
• d: • • • •
0.14 0.26 0.39 0.21 0.30 0.29
3.60 1.45 3.31 6.96 9.50
• 0.44 • 0.10 • 0.20 • 0.36 • 0.74
7.0 •
1.1
9.86 ~- 0.71
5.59 •
0.86
6.62 •
0.35
9.82 • 11.42 • 7.02 •
0.43 0.46 0.51
14.62 • 17.4 •
0.78 1.6
6.13 7.99 5.88 5.30
0.28 0.34 0.28 0.46
6.50 9.53 7.95 8.46
0.88 0.45 0.41 0.72
• • • •
• • • •
14.9 • 17.74 •
0.79 2.5 0.87 0.29 0.32
650MeV/u Ar-40
5.65 •
0.38
6.34 •
0.41
4.85 •
0.31
1.4
1.0 0.94 104 • 13 14.36 • 0.82 10.44 • 0.64
41.0 32.3 27.3 24.3
+ 5.0 • 1.6 • 2.0 • 1.2
18.42 • 21.3 •
0.86 3.7
19.49 •
0.68
15.86 • 12.91 •
0.75 0.71
6.22 • 8.59 •
0.39 0.57 (continued)
in the n e u t r o n - r i c h r e g i o n o f the n u c l e a r chart if o n e looks at the region o f m a s s n u m b e r s less than about a h a l f o f the target n u c l e u s . This result is not p r e d i c t e d b y the s y s t e m a t ics o f f r a g m e n t a t i o n like E P A X II f o r m u l a [6] d e s c r i b e d below. Isobaric yields for the s y s t e m s w i t h 180 M e V / u and 400 M e V / u 12C w e r e d e d u c e d f r o m the cumulative yields w h i c h are c o n s i d e r e d to c o r r e s p o n d to m o r e than 90 % o f the former. The yields are d e p i c t e d in Fig. 2 and c o m p a r e d there w i t h the calculation b y E P A X II formula, w h i c h w a s p r o p o s e d b y S t i m m e r e r and B l a n k as a s y s t e m a t i c s for limA414
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Table 1 (continued).
Nuclide Tc Tc Ru Mo Rh Rh Rh Rh Ag Ag In In Sb Te Te Te Xe Xe Te I I I Xe Xe Ba Cs Cs Ba Ce Pm Eu Gd Gd Gd Tb Tb
95 g 96 g 97 99 99 g 99 m 100 g 101 m 105 g ll0m 109 g 111 g 117 119 g 119 m 121 g 122 123 123 m 121 123 132 g 125 g 127 g 128 129 132 131 g 139 g 143 147 147 149 153 151 g 152 g
Half-Life 20 H 4.28D 2.9 D 2.75 D 16.1 D 4.7 H 20.8 H 4.34 D 41.29D 249.9D 4.2 H 2.83D 2.8 H 16.05 H 4.69 D 16.8 D 20.1 H 2.08 H 119.7 D 2.12 H 13.2 H 2.3 H 16.9 H 36.41 D 2.43 D 32.1 H 6.48 D 11.8 D 137.7 D 265 D 24 D 38.1 H 9.4 D 242 D 17.6 H 17.5 H
180 MeV/u C- 12 3.89 5.86 2.49 2.29 3.20 5.83 6.67
10.8 9.91 14.9 12.0 2.08 11.02 12.00
+ + .4.4• + +
.4+ + • • • +
0.13 0.28 0.16 0.23 0.30 0.67 0.30
1.2 0.46 1.1 1.3 0.12 0.49 0.86
400MeV/u C- 12
9.7 • 1.5 10.41 + 0.80 8.20 + 0.40
1.2
20.6
• 1.4
0.13
13.58 +
0.66
19.22 +
0.96
11.40 + 0.89 13.17 • 0.64 21.3 + 1.0
12.77 16.45 10.85 19.9
0.68 0.98 0.82 1.0
16.5 18.52 21.52 26.6
17.4 + 19.4 + 23.07 •
.4.4+ +
2.7 3.7 0.94
650MeV/u Ar-40 16.02 + 5.26 •
0.81 0.54
12.73 4- 0.65
19.0 -4- 1.5 24.3 + 1.4
13.07 • 0.65 11.60 4- 0.82 0.29 +
+
•
9.31 .4- 0.46
0.17
24.5
24.5 4.43 4- 0.30 5.91 4- 0.30
0.45 •
4- 1.2 + 0.84 + 0.99 • 1.0
290MeV/u Ar-40
13.14 4- 0.65
15.45 +
24.1 15.9
0.79
19.5
.4- 2.0
27.7
+ 1.5
25.4 43.1
+ +
20.9
• 1.4
.4- 1.3 4- 2.4
20.10 +
0.92
19.5 • 1.1 7.90 • 0.43 24.6 27.1
+ 1.3 • 2.2 1.3 2.3
1.7 43.7
+ 3.0 (continued)
i t i n g f r a g m e n t a t i o n [6]. T h e l i m i t i n g b e h a v i o u r a p p e a r s to b e a t t a i n e d i f o n e c o m p a r e s t h e y i e l d s o f t h e s y s t e m s o f d i f f e r e n t i n c i d e n t e n e r g i e s . It w a s f o u n d t h a t t h e s y s t e m a t i c s reproduces the measured values fairly well as a general trend, while there was some deviation from the measured
v a l u e s . T h e d e v i a t i o n is still a n o p e n q u e s t i o n a n d n o w u n d e r
investigation from a point of view of contribution from the other possible mechanisms. In the simulation experiment for the practice of continuous production of the tracers, t h e r e c o i l y i e l d f r o m t h e P t t a r g e t w a s p l o t t e d vs. p r o d u c t m a s s i n F i g . 3. T h e d a t a a r e
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Table 1 (continued).
Nuclide Tb Tb Tb Tb Dy Er Er Tm Tm Yb Lu Lu Hf Hf Hf Ta Ta Re Re Os Os Pt Ir Ir Pt Pt Au Au Au Au Au Hg TI
153 154 154 155 157 160 161 165 167 169 170 171 170 173 175 176 178 182 183 183 185 188 186 189 191 197 192 194 195 196 196 197 200
ml m2
g g
m m g
B
g g g g m m
Half-Life 2.34D 9H 22.6 H 5.32D 8.1 H 28.6 H 3.24 H 1.253 D 9.24 D 32.02D 2D 8.22 D 16 H 23.9 H 70D 8.08 H 2.45 H 12.7 H 70 D 13 H 93.6 D 10.2D 15.8 H 13.2D 2.9D 18.3 H 5.03 H 39.5 H 183 D 6.18 D 9.7 H 23.8 H 26.1 H
180 MeV/u C- 12
400MeV/u C- 12
290MeV/u At-40
650MeV/u Ar-40 22.0 4- 1.1 60.7 4- 3.3 32.7 4- 2.2
34.1 30.1
4- 1.7 4- 1.4
29.1 4- 1.9 17.53 4- 0.89
36.0 35.3 34.4 39.4 45.5 47.5
444444-
1.8 1.7 1.7 2.8 2.7 1.7
25.3
45.6 4- 2.2 65.8 4- 4.7
43.1 36.1
32.4 • 1.3 4- 1.3
33.6 4- 2.0 51.0 4- 4.7
49.2 71.0
4- 2.6 4- 3.2
40.4 4- 1.8 68.7 4- 6.8 4- 2.2 4- 3.0
71.2 65.4 32.4 64.7
4444-
3.3 2.9 1.3 2.8
91.8 4- 4.7 15.05 4- 0.85 27.0 4- 3.3
59.4 4- 2.9
71.3
+
4.8
76.1 79.1
• 3.4 4- 2.4
65.7 4- 2.7 59.7 4- 2.0
89.6 4- 9.0 92.9 4- 6.7
211 4- 11 100.3 4- 5.0 109.0 4- 5.5
77.6 4- 3.3 116.3 •
6.0 109.3 4- 6.1 62.3 4- 4.3 93 4- 10
103.0 4- 8.3 126.0 4- 5.9 247 4- 24
119 4- 13 3.61 4- 0.57
192.0 35.8 1.61 8.61
444•
7.5 1.9 0.39 0.84
80.1 4- 3.7
524 4- 20
c o m p a r e d to t h e p r e d i c t i o n w i t h t h e e f f e c t i v e s i z e o f p o w d e r u s i n g t h e r e c o i l d a t a i n ref. [3]. It w a s f o u n d t h a t t h e y i e l d w a s m o r e t h a n 1 0 % f o r t h e m o s t o f m a s s r e g i o n o f t h e observed products although the data does not agree very well with the prediction. The r e s u l t s h o w s a g o o d p o s s i b i l i t y o f t h e e x t r a c t i o n o f m a n y n u c l i d e s f r o m t h e p o w d e r target with high efficiency.
References [1] Lynch, W. G.: A n n . Rev. Nucl. Part. Sci. 37 (1987) 493. [2] K a u f m a n , S. B., Steinberg, E. P., Wilkins, B. D., a n d H e n d e r s o n , D. J.: P h y s . Rev. C22 (1980) 1897. [3] Yokoyama, A. et al.: R a d i o c h i m . A c t a 89 (2001) 703. [4] Baba, H., Sekine, T., Baba, S., a n d Okashita, H.: J A E R I - m e m o No.1227 (1972). [5] R e u s , U. a n d Westmeier, W.: At. D a t a a n d Nucl. Data Tables 29 (1983) 1. [6] Siimmerer, K. a n d Blank, B.: Phys. Rev. C61 (2000) 034607.
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