Measurement of (n, p) cross-sections for shortlived products by 13.4–14.9 MeV neutrons

Measurement of (n, p) cross-sections for shortlived products by 13.4–14.9 MeV neutrons

Pergamon Ann, Nucl. Energy, Vol. 25, No. 1-3, pp. 23-45, 1998 © 1997 Elsevier Science Ltd. All rights reserved PlI: S0306-4549(97)00040-6 Printed in ...

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Pergamon

Ann, Nucl. Energy, Vol. 25, No. 1-3, pp. 23-45, 1998 © 1997 Elsevier Science Ltd. All rights reserved PlI: S0306-4549(97)00040-6 Printed in Great Britain 0306-4549/97 $17.00 + 0.00

MEASUREMENT OF (n, p) CROSS-SECTIONS FOR SHORTLIVED PRODUCTS BY 13.4-14.9 MeV NEUTRONS YOSHIMI K A S U G A I , 1, HIROSHI YAMAMOTO,1 KIYOSHI K A W A D E 1 and T O S H I Y U K I IIDA 2 IDepartment of Energy Engineering and Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-01, Japan 2Department of Electronic, Information Systems and Energy Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565, Japan (Received 13 March 1997)

Abstract--The 28 (n, p) activation cross-sections that lead to short-lived nuclei with half-lives of between 20 s and 18 min were measured in the energy range 13.4-14.9MeV using an activation method. The measured isotopes were 19F, 28,29Si, 37C1, 5°Ti, 52,53,54Cr, 6°,62Ni, 66,6SZn, s6'SSSr, 97M0, 101,102,104Ru' 104,105, lOSpd' 107Ag' ll6Cd and 119,12°Sn. The intense 14MeV neutron source facility (OKTAVIAN) at Osaka University was used for irradiation. The ?'-rays emitted from the irradiated samples were measured with high-purity germanium (HPGe) detectors. All cross-section values were obtained relative to the standard reaction cross-section of 27A1 (11, t~) 24Na. The present results wexe compared with previous data and the evaluated data of JENDL-3 and ENDF/B-VI. Ten reactions were obtained at multi-pointenergies for the fn'st time. By using intense neutron sources and making careful corrections, reliable results could be obtained. Most of the data obtained previously at multi-point-energies have shown reasonable agreement within 25%. In comparing I0 experimental reactions with the evaluated data, significant discrepancies of more than 25% were seen for three reactions. © 1997 Elsevier Science Ltd 1. INTRODUCTION Knowledge of the nuclear response of 14 MeV neutrons is required for the design of fusion reactors. This includes all neutron-induced reaction cross-sections, y-ray production cross-sections, energy distributions of emitted charged particles, and decay data for *Present address: Department of Reactor Engineering, Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki-ken 319-1 l, Japan. 23

24

Y. Kasugai et al.

radioactive isotopes. Evaluated data files such as JENDL-3 and ENDF/B-VI are used in calculations on nuclear transmutation rates, nuclear heating, radiation damage due to gas formation in potential first wall materials, induced activity and so on. Future success in fusion research and development depends on maintaining and improving existing data base by using the new experimental data. The safety margin within the design can become too large for the manufacture of fusion devices if the database contains a large degree of ambiguity. The database has not often included reaction cross-sections of short-lived products. From the view point of gas production, we need to know all (n, p) reaction cross-sections including both short- and long-lived products. The values of the half-lives of the products do not matter. Recently the need for the cross-section data producing short-lived nuclei has been recognized, and evaluations of reaction cross-sections of short-lived products have begun. However the cross-section data have often not been measured to a reasonable level of accuracy, and there are no data available for some reactions because of the difficulty in measuring short-lived activities. The evaluated data need to be improved experimentally. The cross-section data for short-lived products were measured systematically using an intense D - T neutron source (OKTAVIAN) at Osaka University. In the present work 28 cross-sections for (n, p) reactions leading to short-lived nuclei with half-lives of between 20s and 18rain were measured at neutron energies of between 13.4 and 14.9 MeV using an activation method. A survey of values for (n, p) cross-sections in the literature shows that the previous values were obtained mostly around 14.7 MeV, and these values show considerable disagreement each other. As an extreme example, the previous values for the 6°Ni (n, p) 6°~Co reaction differ by a factor of 13. Isomer crosssections have not yet been evaluated for the isotopes of 6°,62Ni, 86Sr, 97Mo l°2Ru, 1°4,1°5pd, l°7Ag and 119,12°Sn. In this paper, the experimental procedure is given in Section 2. A complete set of crosssection data are shown in digital form and in the figures in Section 3. Our data are compared with previous experimental values and the evaluations of JENDL-3 and ENDF/BVI. The conclusion is given in Section 4.

2. EXPERIMENT 2.1. Irradiation and flux determination

The D - T neutrons were generated by bombarding Ti-3T mounted on a rotating target with a d + beam of 5 mA and 300 keV using the OKTAVIAN facility at Osaka University. A pneumatic sample transport system as shown in Figs 1 and 2 was used to irradiate the samples. The transfer time was about 2-4 s. The angles of irradiation with respect to the d ÷ beam were between 0 and 155°, which covered the neutron energies in the range 14.9-13.4 MeV. In the early stage of the experiments, the samples were irradiated at angles of 0, 45, 70, 95, 120 and 155° (set 1 shown in Fig. 1). In the present arrangement the samples were irradiated at angles of 0, 50, 75, 105, 125 and 155° (set 2 shown in Fig. 2). Another pneumatic tube was also set at - 9 5 ° in set 1 ( at -105 ° in set 2) in order to examine the arrangement of pneumatic tubes. When the pneumatic tubes were correctly set, the obtained cross-sections of the irradiations at 95 and - 9 5 ° (or at 105 and -105 °)

Measurement of (n,p) cross-sections

25

o 95°'" 700 45° 120~ ] ~ ~~ calibrati°n

~

T

large ~~m~-

0o

ml-

-95°T

Fig. 1. Pneumaticsample transport system of set 1. should show good agreement. The distance between the T-target and irradiation positions was 15cm. Typical neutron fluxes at each the irradiation position were 0.91.5xl0Sn/cm2s. An additional tube for calibration is shown in Figs 1 and 2. It was placed at a distance of 1.5cm from the T-target and was used to produce the intense activity needed to calibrate HPGe detectors. This method for efficiency calibration is described in detail in Section 2.3. The ratio of the neutron flux at 1.5 cm to that at 15 cm was about 50. The neutron flux at the sample position was measured using the 27AI (n, p) 27Mg reaction. The cross-section of 27A1 (n, p) 27Mg was determined by referring to the standard 27A1 (n, or) 24Na reaction (ENDF/B-VI). The samples were sandwiched between two A1 foils of 10 × 10 mm and 0.2 mm thickness, and were put in a sample cartridge shown in Fig. 3. The fluctuation in the neutron flux during the irradiation was monitored at an interval of 3 s using a fission counter. The effective neutron energies of the incident neutrons at each irradiation position were determined by the reaction ratio of 9°Zr (n, 2n) 89Zr (Pavlik et al., 1982) to that of 93Nb (n, 2n) 92mNb (Lewis and Zieba, 1980; Nethaway, 1985). The experimental result and calculation of the kinematics in case of kinematic energy of d ÷ beams; Ea = 100, 130 and

155°

d÷lmam

T

target~ 'J

ion

-1 o s °

Fig. 2. Pneumaticsample transport system of set 2.

26

Y. Kasugai et al.

-Sample & Cartrige

Cl3

~

AI

~PN~Sample Fig. 3. Sample cartridge and sample.

150 keV are shown in Fig. 4. The measured effective neutron energies were well reproduced with the value of Ed = 130 keV. This result can be reasonably understood by considering the energy loss of d ÷ beam in the T-target and the T (d, n) 4He excitation function. The uncertainty in the neutron energy is estimated to be + 50 keV from the d + beam diameter of 25 mm, sample size, the distance of 15 cm and the uncertainty in the Nb/ Zr method. 15.0

~

r

. j.

~

~

eZ 14.5

,

'

:E

I~

14.0

C "~

13.5

Z

--

- -

13.0 -150

'~I,,~_

- - Ed=100keV |

Ed=13okov I

1-:

,I

I

I

I

I

I

-100

-50

0

50

100

150

Angle(degree)

200

Fig. 4. Angular dependence of D-T neutron energy. The calculated neutron energies forEd = 100, 130 and 150 keV are shown. The measured neutron energies were well reproduced when the value of Ed was chosen to be 130 keV.

Measurement of (n,p) cross-sections

27

2.2. Sample preparation Mass separated isotopes from the Oak Ridge National Laboratory and of natural abundance were used as samples. Powder samples were wrapped in powder papers. Each sample was 10x 10 mm with a thickness of about 1-2 mm, typical sample masses were 2070mg. The foil samples were rectangular in shape 10x 10mm and 0.1q).2mm thick. The isotopic compositions of samples used are shown in Table 1.

2.3. Activity measurement Gamma-rays emitted from the irradiated samples, and the AI foils for neutron fluence monitoring, were measured with 12 and 16% HPGe detectors, respectively, at 5 cm from the surface of the HPGe detectors. When low energy ),-rays below 100 keV were to be measured, a low-energy-photon-spectrometer (LEPS) with a thin Be-window was used. The characters of Ge detectors used in this work are listed in Table 2. Each detector was covered with 5-mm thick acrylic absorbers in order to reduce/~-rays. The full-energy peak Table 1. Sample properties Target nucleus

Chemical Weight form (mg)

19F 285i 29Si 37C1 5°Ti 52Cr 53Cr 54Cr 6°Ni 62Ni 66Zn 6SEn 86Sr 88Sr 97Mo

(CFz)n Si SiO2 CzH3CI TiO2 Cr Cr20 3 Cr20 3 Ni Ni ZnO ZnO SrCO3 Sr Mo

lmRu I°2Ru I°4Ru 104pd 1°SPd l°Spd l°7Ag 116Cd

Ru Ru Ru Pd Pd Pd Ag CdO

60 47 37 16 30 38 70 43

l!9Sn

SnOz

65

12°Sn

SnO2

65

190 70 60 50 50 85 50 30 70 40 80 370 90 80 50

Abundance (%) Natural (19F: 100) Natural (28Si: 92.23, 29Si: 4.67, 3°Si: 3.10) 2ssi: 4.12, 29Si: 95.65, 3°Si: 0.23 Natural (35C1: 75.77, 37C1:24.23) 46Ti: 0.27, 47Ti: 0.25, 4STi: 2.40, 49Ti: 0.33, 5°Ti: 96.75 Natural (S°Cr: 4.35, 52Cr: 83.79, 5aCr: 9.50, 54Cr: 2.36) 5°Cr: 0.027, 52Cr: 1.665, 53Cr: 98.23, 54Cr: 0.077 S°Cr: 0.06, 52Cr: 2.26, S3Cr: 0.90, 54Cr: 96.78 58Ni: 0.29, 6°Ni: 99.65, 61Ni: 0.03, 62Ni: 0.03, 64Ni: < 0.08 58Ni: 8.45, 5°Ni: 6.12, 61Ni: 1.40, 62Ni: 97.01, 64Ni: 0.20 64Zn: 0.86, 65Zn: 98.41, 67ZH: 0.20, 63Zn: 0.53, 7°Zn: < 0.005 Natural (64Zn: 48.6, 65Zn: 27.9, 67Zn: 4.1, 63Zn: 18.8, 7°Zn: 0.62 84Sr: 0.08, 86Sr: 97.02, 87Sr: 0.78, 88Sr: 2.12 Natural (S4Sr: 0.56, 86Sr: 9.86, S7Sr: 7.00, SSSr: 82.58) 92Mo: 0.22, 94Mo: 0.24, 95Mo: 0.59, 96Mo: 1.34, 97Mo: 94.25, 9SMo: 3.07, l°°Mo: 0.30 99Ru: 0.24, I°°Ru: 0.64, lmRu: 96.03, l°2Ru: 2.73, I°4Ru'. 0.36 99Ru: 0.12, l°°Ru: 0.15, lmRu: 0.37, l°2Ru: 98.95, l°4Ru: 0.41 99Ru: 0.10, I°°Ru: 0.13, lmRu: 0.23, l°2Ru: 0.49, l°4Ru: 99.05 l°4pd: 96.02, l°SPd: 4.48, l°6pd: 1.15, l°SPd: 0.79, 11°Pd: 0.56 l°4pd: 0.41, l°5Pd: 96.58, l°SPd: 2.35, l°3pd: 0.46, ll°pd: 0.20 l°4pd: 0.15, l°Spd: 0.31, l°6pd: 0.39, l°Spd: 98.79, ll°Pd: 0.36 1°7Ag: 99.09, l°9Ag: 0.91 l°6Cd: 0.07, I°SCd: 0.02, ll°Cd: 0.24, lllCd: 0.58, ll2Cd: 0.74, 113Cd:0.73, l l4Cd. 2.65, l l6Cd" 94.97 II6Sn: 0.40, 117Sn: 0.85, llSSn: 3.63, 119Sn: 84.48, 12°Sn: 9.98, ll2Sn: 0.44, 124Sn: 0.20 ll6Sn: 0.13, 117Sn: 0.11, 118Sn: 0.61, ll9Sn: 0.66, 12°Sn: 0 34, 122Sn 0.84, 124Sn: 0.10

Y. Kasugai et al.

28

Table 2. Character of the Ge detector used for the cross-section measurement Detector p-type HPGe n-type HPGe n-type HPGe

Volume (cm3)

Efficiency (%)

FWHM (keV)

Object of measurement

60 30 89

12 4 16

1.75a 0.61b 2.00a

E), > 80 keV E~/< 80 keV A1 nonitor foil

aAt 1332keV. bat 122 keV efficiencies at 5 cm were calibrated with sources of 241Am, 133Ba, 6°Co, 24Na, 152Eu, and 56Co. Coincidence summing effects were taken into consideration. The efficiency data between 50 and 340keV were fitted with a function using a six-fitting parameter, and those between 340 and 3000 keV using a seven-fitting parameter. The errors in the efficiency curves are estimated to be 1.5% above 300keV, 3% between 300 and 80 keV, and 5% below 80 keV. In order to obtain good statistics we very often had to put the irradiated samples with weakly induced activities on the surface of the HPGe detectors at 5 mm. However, it is difficult to obtain the detection efficiency curve at 5 mm to a good accuracy using the above-mentioned multi y-ray emitters because corrections for the true coincidence sum effect are large at low distances and it is difficult to correct the sum effects precisely. In order to measure induced low-level activities efficiently and to avoid such the sum effects, the ratios of the efficiencies at 5 mm and 5 cm were measured for various activities and applied to convert the detection efficiency at 5 mm to that at 5 cm. We call the procedure of detection efficiency conversion from 5 mm to 5 cm a calibration method. The calibration measurements were carried out by using either extra or the same samples irradiated with a rather intense neutron flux at the calibration tube which was set at 1.5cm and 0 ° . This method improved the detection efficiency by a factor of about 7 compared with the measurements at 5 cm. This calibration procedure brought an additional error of only 1.0% to the results. The details are described elsewhere (Kawade et al., 1989).

2.4. Decay data

In Table 3, associated decay data of half-life, y-ray energy and y-ray emission probability (absolute intensity in photons per disintegration) are listed together with measured reactions and Q-values. Most of the decay data were taken from the Table of Radioactive Isotopes (Browne and Firestone, 1986). Data obtained since publication of the Table of Radioactive Isotopes are also listed in the table. The half-lives of 2SA1, 37S, 52V, 6°mCo, 97mNb and l°4mRh were measured by us (Miyachi et al., 1988; Yamamoto et al., 1991). Cheung et al. (1978) reported that 12°In has two isomers with similar half-lives of 46.2 and 47.3 s. We remeasured the half-lives to be 42.4(8) and 45.6(7)s, respectively (Kgsugai et al., 1993). The previous data of 12°Sn (n, p) cross-sections were measured without the separation of two isomers. The 1039keV 7-ray emission probability of 66Cu was evaluated to be 7.4+ 1.9%. Recently a new value of 9.23+0.09% has been obtained (Miyahara et al., 1993). Our cross-section data of 66Zn (n, p) 66Cu show a lower value than previous data because the new value of y-ray intensity is 20-30% higher than

Measurement of (n,p) cross-sections

29

Table 3. Measured reactions and decay parameters a Reaction 19F(n,p)190 28Si(n,p)28Al 29Si(n,p)29Al

37Cl(n,p)37S S°Ti(n,p)5°m + gSc 52Cr(n,p)52V 53Cr(n,p)Sav 54Cr(n,p)54V 6°Ni(n,p)6°mCo 6ZNi(n,p)62mCo

62Ni(n,p)62gCo 66Zn(n,p)66Cu 68Zn(n,p)68Cu 86Sr(n,p)S6mRb 88Sr(n,p)SSRb

97Mo(n,p)97mNb l°lRu(n,p)l°lTc l°2Ru(n,p)~°2mTc l°4Ru(n,p)l°aTc l°4pd(n,p)l°4mRh l°SPd(n,p)l°SmRh I°Spd(n,p)l°SgRh l°7Ag(n,p)l°Tmpd

116Cd(n,p) 116gAg l l9Sn(n,p)ll9gln 119Sn(n,p)l lamln 12°Sn(n,p)12°mlIn

12°Sn(n,p)12°m21n

Tl/2

ET(keV)

I~,(%)

Q(MeV)

26.91 s 2.241 m 6.56 m 5.05 m 1.710 m 3.75 m 1.61 m 49.8 s 10.42 m 13.91 m 1.50 m 5.10 m 3.75 m 1.017 m 17.8 m 58.75 m 14.2 m 4.35 m 18.3 m 4.26 m 42.4 s 6.0 m 21.3 s 2.68 m 2.4 m 18.0 m 43.5 s 45.6 s

197.1 1779.0 1273.4 3104.0 523.8 1431.0 1006.2 834.8 58.6 1163.5 1129.1 1039.4 525.7 556.1 1836 743.4 306.8 475.1 358 51.4 129.6 581.0 214.9 513.5 763.1 743.4 1171.3 197.1

95.9 + 2.1 100 91.3 94.2 + 0.6 88.7 + 1.8 100.0 90 ± 2 97.1 :i: 1.7 2.0 + 0.1 68.1 ± 1.4 11.3 ~: 0.7

-4.04 -3.86 - 1.89 -4.08 -6.11 -3.19 -2.65 -6.26 -2.46 -4.48 --4.46 - 1.86 -4.56 - 1.55 -4.53 - 1.89 -0.84 -3.74 -4.83 -1.79 -0.086 -3.65 -0.53 -5.21 - 1.55 - 1.89 -4.52 -4.52

9.23 ± 0.09 b 75 ~: 15 98.19 :~ 0.01 21.4 ± 1.2 97.95 & 0.10 88 + 4 85.3 ~: 2.0 79 :~ 10 48.3 • 0.5 20.0 • 0.4 59 ± 12 69 ± 2 76 ± 4 99.08 ± 0.15 97.95 + 0.10 96.1 ± 1.0 80.6 ± 3.1

aTaken from Table of Radioactive Isotopes (Browne and Firestone, 1986). bTaken from Miyahara et al. (1993).

the values used previously. V i e n n o t et al. (1991) used the value o f 8 + 1%. By using the new value for the 7 - r a y intensity, their d a t a are revised to a value 15% lower.

2.5. Corrections I n d e d u c i n g the cross-sections the following p r i n c i p a l c o r r e c t i o n s were m a d e : (1) fract i o n a l c o n t r i b u t i o n o f low energy neutrons, (2) fluctuation o f n e u t r o n flux, (3) c o u n t i n g loss due to coincidence sum effect, (4) d e v i a t i o n o f 7 - r a y d e t e c t i o n efficiency d u e to s a m p l e thickness, (5) s e l f - a b s o r p t i o n o f 7-rays. D e t a i l s o f the c o r r e c t i o n s are given below.

Fractional contribution of low energy neutrons.

T h e incident n e u r o n s p e c t r a are n o t m o n o e n e r g e t i c . T h e r e are low energy c o m p o n e n t s b e l o w the D--T p e a k o w i n g to scattering. T h e n e u t r o n s p e c t r u m was t a k e n at 70 ° with respect to the d + b e a m d i r e c t i o n b y m e a n s o f a two crystal m e t h o d ( T a k a h a s h i et al., 1986). T h e s p e c t r u m is s h o w n in Fig. 5.

Y. Kasugai et al.

30

10 s

. . . .

~

. . . .

~

. . . .

n . . . .

10 4

°'j / o

X Ur" 0 -a Q~

Q

10 3

z

~ _ _ ~ . . . .

_ ..~_ _ _ ,

. . . .

~./Energ., y, Cut-off

~

10 2

0

5

10

20

15

Neutron Energy(MeV) Fig. 5. Neutron spectra measured at 70° with respect to d + beam directed by the two-crystal method.

When a cut-off energy between the D-T peak and the low energy components was set at 10 MeV, the low energy components were about 15%. To determine the cross-sections around 14MeV accurately, the contribution of low energy neutrons should be taken into account. (n, p) reactions in particular are largely affected by the low energy components, because the reactions have low threshold energy and the excitation functions range down to the low energy region. The contributions of low energy neutrons to total reaction rate, FC, were estimated by using following equation,

FC=

E-i=O

}

O(Ei) • a(Ei) + ~xCrx [Ei-----0

where ~(Ei) and ~x are neutron flux at the neutron energy Ei and Ex, respectively, and tr(Ei) and trx are cross-sections at Ei and Ex. Summation is taken from Ei=0 to Ec = 10 MeV, Here we assumed that neutrons above Ec are nearly monoenergetic with an energy Ex. A correction factor (Fs) for FC is given by

F~-

1 - FC(n, X) 1 - F C ( n , or)

where FC(n, p) and FC(n, a) are the FCs for the (n, p) reaction of interest and the standard 17AI (n, a) Z4Na reaction, respectively. The FCs were calculated by using excitation functions from JENDL-3, and from Yamamuro's calculation (Yamamuro, 1990), in the case of no experimental excitation function. When there are no evaluation data, FCs were

Measurement of (n,p) cross-sections

31

estimated from the slope of partial excitation function measured. In Fig. 6, the values of FC are plotted as a function of relative slope; RS, defined as

RS =

/a at 14.0 MeV

where (A~r/AE) is the slope of the excitation function and a is a cross-section at 14 MeV. The values of RS are almost on a smooth curve. This curve serves to estimate quickly FCvalues when no excitation curve is known.

Fluctuation of neutron flux. The neutron flux varies during the irradiation due to the consumption of tritium in a target and to the fluctuation of d + beams. This effect contribute to the final result by less than 3% in the opeartion of O K T A V I A N and uncertainty is less than 0.5%. Counting loss due to coincidence sum effect. If a radioactivity decays with de-excitation via cascade y-rays, there is a certain probability for the simultaneous detection of y-rays. To estimate the count loss due to true coincidence-sum effect, the total efficiency at 5 cm was measured by using sources of 54Mn, 57Co, 65Zn and 137Cs. When the counting rate is over 103 s -1, the counts were lost due to the pile-up effect. Since counting rates were less than 103 s -1 in most cases, this effect was negligibly small. Deviation of y-ray detection efficiency due to sample thickness. The mean position of the samples was a little different to the position owing to the thickness of samples. The correction was made by means of effective-length of the Ge detectors (Kawade et al., 1981). The thicknesses of the samples are 0.1-2 mm. When the thickness of the samples is 2 mm, this effect contributes to the final results by 6%. Self-absorption of y-rays in the sample material. When the source-to-detector distance is large, the one-dimensional treatment is reasonably accepted. The thickness of the sample is usually less than 100 mg/cm 2, hence the correction factor (fa) is approximately given by 15

:3

. . . .

10

i

. . . .

i

. . . .

i

. . . .

i

. . . .

L

. . . .

I

. . . .

i

. . . .

0

~ e-0

0

0

o s

0 It..

O.,Q, -3o

-2o

40

o

~o

20

30

40

so

Slope at 14 MeV (%/MeV) Fig. 6. Fractional contributions (FC) of low energy neutrons as a function of slope of excitation function at 14.0 MeV.

32

Y. Kasugai et al.

fa

=

al~t 1 1 - exp(-a/zt) "-" 1 - 0.5alzt

where o is the density of the sample (g/cm3), t is thickness (cm) and /z is the mass absorption coefficient (cm2/g). When there are two different reactions producing the same activity in the irradiated sample, the cross-sections of two competing reactions were separately deduced by irradiating the two kind of samples which have different constitutions of isotopes.

Interfering reaction.

2.6. Error estimation

The following contributions to the uncertainties in the cross-sections were taken into account. They stemmed from experimental errors. Typical values of relative errors are shown in parentheses 1. low energy neutrons (< 2%) 2. neutron-flux fluctuation (< 0.4%) 3. detector efficiency; described in Section 2.3 4. efficiency conversion ratio between close and standard position (1.0-2.0%) 5. true coincidence sum (< 0.6%) 6. random coincidence sum(< 0.1%) 7. sample weight (< 0.1%) 8. self-absorption of y-ray (0.2-4%) 9. Statistical error of y-ray count (1-20%) 10.y-peak evaluation (< 0.5%) The following were considered as contributing to the errors in the nuclear data: 1. reference cross-section for 27A1 (n, t~) 24Na (3.0%) 2. absoluter y-ray intensity (0.3-10%) 3. half-life (0-10%) The total relative errors (~t) were derived by combining the experimental error (Be) and the error of nuclear data (St) in quadratic:

In many cases major sources of error are statistical errors in the ?,-ray counts. In some cases errors in the nuclear data were dominant. When good counting statistics were achieved and the error of half-life and y-ray intensity were small, the total error was 3.6%.

3. RESULTS AND DISCUSSION Numerical data from the present cross-section are given in Table 1 and graphs are given in Fig. 7, together with the data previously reported and with the evaluations of JENDL-3 and ENDF/B-VI.

Measurement of (n,p) cross-sections

33

Table 4. Results of activation cross-section data

En (MeV)

a (mb)

8~ (%)

~r (%)

tSt (%)

3.6 3.6 3.7 3.6 3.6 3.6

3.7 3.7 3.7 3.7 3.7 3.7

5.2 5.2 5.2 5.2 5.2 5.2

4.5 4.3 4.2 4.2 4.4 3.9

3.0 3.0 3.0 3.0 3.0 3.0

5.4 5.2 5.2 5.2 5.3 4.9

1.9 1.9 2.1 1.9 2.0 1.9

3.0 3.0 3.0 3.0 3.0 3.0

3.6 3.6 3.7 3.6 3.6 3.6

8.4 8.3 7.9 11.4 10.2 7.7

3.0 3.0 3.0 3.0 3.0 3.0

8.9 8.8 8.5 12 11 8.3

4.0 4.1 4.5 4.2 4.2 4.6

3.6 3.6 3.6 3.6 3.6 3.6

5.4 5.5 5.7 5.5 5.5 5.8

3.8 3.6 3.4 3.4 3.6 3.2

3.0 3.0 3.0 3.0 3.0 3.0

4.8 4.7 4.5 4.5 4.7 4.4

4.6 6.2 6.4 6.7 7.2 3.7

3.7 3.7 3.7 3.7 3.7 3.7

5.9 7.2 7.4 7.7 8.1 5.2

5.3 5.6

3.6 3.6

6.3 6.6

19F(n,p)190 (TI/2 = 26.91 s) 14.87 17.8 14.58 18.6 14.28 19.4 13.88 19.5 13.65 20.8 13.40 22.7 28Si(n,p)2SA1 (T1/2= 2.241 rain) 14.87 219 14.64 229 14.35 229 14.02 254 13.70 265 13.40 254 29Si(n,p)29A1 (Tl/z = 6.56 min) 14.87 130.8 14.58 131.6 14.28 131.7 13.88 132.7 13.65 130.6 13.40 125.6 37CI(n,p)37S (T1/2= 5.05 min) 14.87 24.8 14.64 22.3 14.35 22.4 14.02 24.9 13.70 25.9 13.40 25.6 5°Ti(n,p)5°m + gSc (TI/2 = 1.710 min) 14.87 14.4 14.58 13.5 14.28 13.0 13.88 12.0 13.65 10.6 13.40 10.2 52Cr(n,p)52V (T1/2= 3.75 min) 14.87 74.4 14.64 73.6 14.35 79.1 14.02 80.4 13.70 78.3 13.40 85.6 53Cr(n,p)S3V (T1/2= 1.61 min) 14.87 42,8 14.64 45,6 14.35 44.4 14.02 41.2 13.70 44,9 13.40 39.4 54Cr(n,p)Sav (T1/2= 49.8 s) 14.87 21.3 14.58 21.6

34

Y. Kasugai et al. Table 4. continued

En (MeV)

a (mb)

14.28 20.8 13.88 17.5 13.65 13.4 13.40 15.0 6°Ni(n,p)6°mCo (TI/2 = 10.42 min) 14.87 74 14.02 95 13.40 100 62Ni(n,p)62mCo (T1/2 = 13.91 min) 14.87 19.5 14.64 18.3 14.35 16.7 14.02 17.5 13.70 11.9 13.40 13.1 62Ni(n,p)629Co (T1/2= 1.50 min) 14.87 26 14.64 33 14.35 25 14.02 21 13.70 17 13.40 16 66Zn(n,p)66Cu (TI/2 = 5.10 min) 14.87 59.2 14.64 56.2 14.35 53.8 14.02 57.7 13.70 49.7 13.40 59.3 68Zn(n,p)68mCu (TI/2 = 3.75 min) 14.87 5.5 14.64 4.6 14.35 4.9 14.02 4.2 13.70 4.2 13.40 12.0 86Sr(n,p)a6mRb (T1/2 = 1.017 min) 14.87 12.9 14.58 13.2 14.28 12.1 13.88 12.7 13.65 11.1 13.40 10.1 88Sr(n,p)S8Rb(Tl/2 = 17.8 min) 14.87 23 14.64 20 14.35 22 14.02 18 13.70 12 13.40 14

8e (%)

t~r (%)

t~t (%)

6.9 6.0 6.4 6.7

3.6 3.6 3.6 3.6

7.8 7.0 7.3 7.6

8.0 8.0 8.0

5.9 5.9 5.9

10 10 10

6.9 7.1 6.5 5.2 11 5.3

3.6 3.6 3.6 3.6 3.6 3.6

7.8 8.0 7.4 6.4 12 6.4

17 23 19 16 40 15

6.9 6.9 6.9 6.9 6.9 6.9

19 24 20 17 41 17

9.2 8.4 7.8 7.7 9.4 5.4

3.2 3.2 3.2 3.2 3.2 3.2

9,7 9.0 8.4 8.3 10 6.3'

12.0 8.5 7.5 8.0 8.4 12.0

20.2 20.2 20.2 20.2 20.2 20.2

24 22 22 22 22 24

3.8 4.0 4.9 3.6 4.0 4.1

3.0 3.0 3.0 3.0 3.0 3.0

4.9 5.0 5.7 4.7 5.0 5.0

12 11 10 11 21 11

6.4 6.4 6.4 6.4 6.4 6.4

14 13 12 131 23 I3 ( c ontinuetO i

~r I

II

~j

II

II

II

~

II

~

~o

~Z

~P

i

L~

36

Y. Kasugai et al.

Table 4. continued

En (MeV)

o (mb)

8~ (%)

~r ( °fo)

t~t ( °fo)

8.0 8.3

5.2 5.2

9.6 10

10 9.8 ll l0 13 13

6.1 6.1 6.1 6.1 6.1 6.1

12 12 13 12 14 14

5.3 6.3 6.7 6.3 7.2

5.1 5.1 5.1 5.1 5.1

7.4 8.2 8.4 8.1 8.7

10

20

23

12 16 17 17 16

11 11 11 11 11

1.9

18

11

16 18 20 20 19 20

0.95 0.85 0.59 0.48 0.46 0.43

19 29 34 32 32 32

5.1 5.1 5.1 5.1 5. I 5.1

20 24 34 32 32 32

13.65 13.40

7.3 7.7 116Cd(n,p)116gAg (TI/2 = 2.68 min) 14.87 2.30 14.58 1.69 14.28 1.48 13.88 1.33 13.65 0.90 13.40 0.78 ll9Sn(n,p)119gin (Tl/2 = 2.4 min) 14.87 6.25 14.58 5.36 14.28 5.12 13.88 4.08 13.40 3.00 i 19Sn(n,p)119mln (T1/2= 18.0 rain) 14.87 4.69 12°Sn(n,p)12°~qn (T1/2= 43.5 s) 14.87 4.8 14.58 4.0 14.28 3.4 13.88 2.6 13.65 2.8 13.40

12°Sn(n,p)12°m2In (TI/2 = 45.6 s) 14.87 14.58 14.28 13.88 13.65 13.40

*~: exprimental error, 8r: error of nuclear data, 8t: total error, t~t2 = tie2 + ~r 2.

Generally speaking from the comparison with previous data as seen in Fig. 7, the data obtained at multiple neutron energy points show reasonable agreement with the present results in comparison with those obtained at one energy point. This reason can be understood as follows. Most of the one-energy-point data were obtained by irradiating samples at a close distance from the neutron sources because the neutron sources were weak. When the neutron sources are weak, it i s h a r d l y possible to keep enough distance between the irradiated samples and the neutron sources. In general, it is difficult to determine the character of neutron field (for example, neutron energies etc.) at close distances. To obtain multiple-energy-point data, intense neutron sources are needed. F o r the activity measurement, it is not clear whether enough attention was paid to the true coincidence sum effect, although weakly induced activities due to weak neutron sources should have been measured at a distance close to a detector. Hence, the one-energy-point data may be measured without paying enough attention to the neutron fields and activity measurements.

Measurement of (n,p) cross-sections

19F(n, p)190 60

.IQ

E

v

c-

0 0 0

50 40

-

0 -

V

o~

if)

if)

0

o

2SSi(n, p)2SAI

I

•O [] [] X

--

• • i --

30

I

Preseflt P.N.Ngoc '80 L. Hannapel'79 R.A.Sig9 '76 R. Prasad'71 W. Schantl'70 A. Pasquarelli'67 J. Csikai'67 B. Mitra '66 M. Bormann'65 J. Picard'65 J. Kantele'62 - ENDF/B-VI J£NDL-3

I

I

300 ..Q

E

v

¢-

._o

200

o O3 0o

Present

Ikeda'88 Csikai'86 P.N.Ngoc '80 V+T Shchebolev'77 J.C.Robertson J. Ooresler'73 R. Prasad'71 JJ. ~ngh '70 N. Ranakumar J.M.F.Jeronymo'63 CS. Khurana'65 JENDL-3

O0

£ o

10 I

,

13

I

+

100

I

14

I

15

13

Neutron Energy(MeV) Fig. 7.1 Cross-section for the ]9F(n, p)190 reaction.

I

I

I

I

14

15

Neutron Energy(MeV) Fig. 7.2 Cross-section for the 28Si(n, p)28AI reaction.

29Si(n, p)29AI I

I

t

20

0

37

3701(n, p)37S .L

40

I

s

z

~,

i

j

i

150 J:)

~

E

30

v

¢O (b

,4,--i

P,

100

:~

CO

O [] r~ X Z~ O O V

Or) (/)

£ o

Present I P,M. Gopych '90 | Y. Ikeda '88 | P.N. Ngoc '80 | M. Herman '80 l R. Vaenskae '79 | V.T. Shchebolev '77| R. Prasad '71 | W. Schantl '70 l N. Ranakumar '68 1 JENDL-3 I

50

I

13

,

I

14

20 •

£ 0 ,

I

15

Neutron Energy(MeV) Fig. 7.3 Cross-section for the 29Si(n, p)29Al reaction.

10 ~* 0 X

0

I

13

J

I

14

Present

J.P.Gupta'8S P.N.Ngoc '80 M. Hyvoenen'78 S.C,Mathur'75 R. Prasad'71 A. Pasquarelli'S7 J.E.Strain'65 R.S.Scalan'58 A.V.Cohen'56 JENOL-3

J

15

Neutron Energy(MeV) Fig. 7.4 Cross-section for the 37Cl(n, p)37S reaction.

38

Y. Kasugai et al.

5°Ti(n, p)5°rn+gsc 25

I •

.(3 v

20

tO

Present

I

RP~,~K'85 I JP Gupta'ss I

A O

I Ribansky '83

|

09 09 0

~

I

....... '"

I| +

.Q

I |

E tO

T

0 (1)

O3

I

100

T

v Schwerer '76 JENDL-3

15

'

|

Hoan Dac LUC 86

x

E

52Cr(n, p)~2V

I

0

co

10

• O

50

09 09 0

0

Present

M. Viennot '91 Y Ikeda '88 S.K. Ghorai '87 Hoan Dac Luc '86 I, Ribansky '85 O.L Artem'ey '80 M. Vafkonen '76 J Dresler 7 3 R. Prasad '71 I.G. Clator '69 - ENDF/8 VI JENDL-3

X

0 --

0

I

~

13

I

~

14

I 15

13

Neutron Energy(MeV) Fig. 7.5 Cross-section for the 50Ti(n' p)5Om+ gSc reaction.

I

]

'

I

'

14

15

Neutron Energy(MeV) F i g . 7.6 C r o s s - s e c t i o n f o r t h e 52Cr(n, p)52V

reaction.

S3Cr(n, p)53V 60

--

54Or(n, p)54V 25

I

j

i

i

50 v

E tO O

40

E

.o_

° ~

09 09

£

O

15

o

30

[] [] X Z~

20

O • I1~ I~

10

- ---

0

Hoang Oac Luc '86 I Ribansky '85 R Pepelnik '85 B.M Bahai '84 0,1. Art em'ev '80 K Sailer '77 f4 L Moila '77 L, Va~konen '76 R Prasad '71 L. 14usaln '61 0./4. Ch~tendem '61 JENOL-3 - ENOF/8-~I

~ 13

! 14

~ 09 09

10

(-)

5

I R1bansky85 B.M. Bahal '84

.N .I .Molla . . . '77 ..... --

~

I 15

Neutron Energy(MeV) Fig. 7.7 Cross-section for the 53Cr(n, p)53V reaction.

0

I

13

i

O --

M Valkon~ ~tS L HuSain '67 - ENOF/B-VI JENOL-3

=

14

15

Neutron Energy(MeV) Fig. 7.8 Cross-section for the 54Cr(n, p)54V reaction.

ooi

Measurement of (n,p) cross-sections

62Ni(n, p)62mco

6°Ni(n,p)6°mCo

1 50

:~

100

• 0 [] O

Present M. Viennot '9 ] J.D. Hemingway A. Paulsen '67

x

,.'.Pro,ss'60

39

t

3O

.Q

E v

20

E O

~

O (1)

CO

e

°I

50

09 09 O

° ° °,°:

0

I

,

13

10 •

(o

I

I

14

15

0 []

o

Fig. 7.9 Cross-section for the 6°Ni(n, p)6°mCo reaction.

~ 13

Neutron Energy(MeV)

"--" .Q

14

15

Neutron Energy(MeV) Fig. 7.10 Cross-section for the 62Ni(n, p)62mCo reaction.

62Ni(n, p)62gCo 50

Present M. Viennot '91 N.I. Molla '77

66Zn(n, p)66Cu

I

O []

40

Y

Present M. Viennot '9] V.N. Levkovskii '69

8O t-~

E

E v

v

tO (..)

30

E O .m

(f) 09 09

20

O (1) 03 09 09 O

0

lO

o

(J

I

13

,

I

14

,

I

15

Neutron Energy(MeV) Fig. 7.11 Cross-section for the 62Ni (n, p)62gCo reaction.

60

40 o [] [3 x z~ o o v

20

0

I 13

,

I 14

Present M. Wennot '82 J.P. Gup~ta '85 C.V SnnNasaRao '82 N.I. Molla '77 JL Casanova'76 R.A Sigg '76 M Valkone '76 J. Doresler '73 R Prasad'7 I

,

I

15

Neutron Energy(MeV) Fig. 7.12 Cross-section for the 66Zn(n, p)66Cu reaction.

40

Y. Kasugai et al.

86Sr(n, p)BSmRb

6BZn(n, p)sarncu 8

I

I

~

20

I

I

I

7 .Q

E

.O

6

E

V

t-

5

0 (1) 03 m

4

o

2

tO o

k

0 ,m

3

.m ,4..-J

• O [] [] X

0

I

~

I

13

~

2

O

5 • O

[]

0

I

14

10

03 tD o)

Present S,K. Ghorai '95 M. Viennot '82 J.L. Barreira '82 C.V Srinwasa Rao '82 R.A. Sigg 76 V.K. Tikku "72

1

0

15

~ 13

15

i OO

i Present

i

v

40

E c

0

.m

t

97Mo(n, p)9;'mNb

N. Hwoenen '78 N.L Molla '77 Doresler '73 V.K. Tikku '72 R. Fr asad '71 P. Ver~lgopala '71 L. Husain '70 V.N Levkovskii '68 F. Strohal '62 E. Bran~itt '61

A.V.

30 -

-

• [] [] [] X

10 r~ v

r,~

E

0

Present Y. Ikeda '88 A. Marcinkov~ki '85 S. Amemlya '85 O.I. Artem'ev '80 C.V. Srinivasa Rao '79 W.D. Lu '70

c

Co,~n'S6

O .m

E.8. Paul '53 JENDL-3

O

O 0u) 3 u) O

I 15

I

J.P. G ~ t = '85

~'~ .Q

,

Fig. 7.14 Cross.section for the 86Sr(n, p)S6mRb reaction.

Sesr(n, p)88Rb 50

I 14

Neutron Energy(MeV)

Neutron Energy(MeV) Fig. 7.13 Cross-section for the 68Zn(n, p)6SmCu reaction.

Present [ M. H y v o e n e n ' 7 8 L. H u s a i n ' 7 0

2O

CO o9

10

O

O I,.-.

I

13

,

I

14

,

I

15

Neutron Energy(MeV) Fig. 7.15 Cross-section for the SSSr(n, p)SSRb reaction.

0

~

L

13

14

15

Neutron Energy(MeV) Fig. 7.16 Cross-section for the 97M0 (n, p)97mNb reaction.

Measurement of (n,p ) cross-sections

l°2Ru(n, p)l°2mTc

l°lRu(n ' p)l°lTc 40

t~ E

I

' • O [] []

30

I

'

15

,

I

I

Present D. Kielan '93 I J.K. Temperley '70 I P.R. Gray '66 JENDL-3 I

I

• O I~

I

-



i

.Q

Present I Kielan '93 P.R. Gray '66 i

E ro

c

O I1) 03 o9 if)

41

10

o

20

03 0~ 0o

£

o

o 0

I

,

13

I

,

14

0

I

I

I

,

13

15

~

14

I

15

Neutron Energy(MeV)

Neutron Energy(MeV)

Fig. 7. l 7 Cross-section for the ]°lRu(n, p) ]°TTc reaction.

Fig. 7.1 8 Cross-section for the l°2Ru(n, p) ]°2mTc reaction.

104pd(n, p)l°4mRh

l°4Ru(n, p)l°4Tc 10

i

,

i

,

I

30 ..O

.0

E

E

Present

O

Levkovskii '71

I

v

E

E O

.£ o



5

20

O

Q)

03 if)

£

• O [] 0

,

13

I

14

Present D. Kilelan '93 P.R. Gray '75 JENDL-3 =

Il

I

I

15

Neutron Energy(MeV) Fig. 7.19 Cross-section for the l°4Ru(n, p) 1°4Tc reaction.

03 (/) (/) O

10

o 0

r

13

I

14

~

I

15

Neutron Energy(MeV) Fig. 7.20 Cross-section for the l°4pd(n, p) i°4mRh reaction.

42

Y. Kasugai et al.

lOapd(n ' p)l°8gRh

lO5pd(n ' p)l°5mRh 30

I

10

I

@ O

I

I

Present I R. Prasad '71



(9

I

Present I R.L. White '72

..Q v

E tO

v

20

09 09 09

o

cO

°~

{÷{{

O

E O

6O 09 09

10

£

o

o 0

,

13

I

,

14

I 15

0

,

.13

,

O []

R. Prasad '7 I. Wagner '71

15

¢.-

I 15

116Cd(n ' p)l16gAg 3

l

I t

E

v l'0 0

O

.~

10 09 09 O I--.

,

Fig. 7.22 Cross-section for the I°Spd(n, p) l°SgRh reaction.

lO7Ag(n, p)l°7mpd 20

I 14

Neutron Energy(MeV)

Neutron Energy(MeV) Fig. 7.21 Cross-section for the l°SPd(n, p) l°5mRh reaction.

I 13

{{{ { { {

I

I

I

O

R. Pepelnik '85

2

6O 1 0

5

o

0

, 13

I 14

,

I 15

Neutron Energy(MeV) Fig. 7.23 Cross-section for the 1°TAg(n, p) l°Tmpd reaction.

0

I 13

~

I 14

,

I 15

Neutron Energy(MeV) Fig. 7.24 Cross-section for the n6Cd(n, p) 116gAg reaction.

Measurement of (n,p) cross-sections

43

119Sn(n ' p)119mln 15

I

I

O [] [] vE

119Sn(n ' p)llggln 15

1

I Q []• []

S, Lulic '68 Present J. Brozosko '65 I t G.P. Chursin '63 vE

10

tO om ¢..)

0 °m 0

I

S. Lulic '68 Present J. Brozosko '65 I t G.P. Chursin '63

10

O')

O9

u) O

o

(9 0

I 13

,

I

0

i

,

14

I

~

13

15

14

12OSn(n ' p)12oml,m21n

.Q v

E

tO O 0) O9

I Present(45.6s) Present(43.5s) W, Struwe'74 G,P. Chursin '63 A. Poularikas'60

I

5

om

09

o9

o o

$ 0

I 13

I 15

Fig. 7.26 Cross-section for the 119Sn(n, p) ~9gIn reaction.

Fig. 7.25 Cross-section for the llgSn(n, p) ] 19rain reaction.

• • [] [] X

~

Neutron Energy(MeV)

Neutron Energy(MeV)

I

,I

J

I 14

,L

I 15

Neutron Energy(MeV) Fig. 7.27 Cross-section for the t2°Sn(n, p) 120ml'm2In reaction.

44

Y. Kasugai et al.

Table 5. Comparisonwith the previous data

]9F(n,p) 2sSi(n,p) 29Si(n,p) 37Ci(n,p) 5°Ti(n,p) 52Cr(n,p) 53Cr(n,p) 54Cr(n,p) 6°Ni(n,p)m 62Ni(n,p)m 62Ni(n,p)g 66Zn(n,p) 6SZn(n,p)m SSSr(n,p) 97Mo(n,p)m l°lRu(n,p) l°2Ru(n,p)m 1°4Ru(n,p)

JENDL

ENDF

X O A O C C O X

O

Ikeda Viennot

O Borrnann 63 C Csikai 86 O Herman 80 O Mather 75, X Cohen 56

O O C O X

O O A

Others

C A A X O A O*1 A

X O O

A Hyvoenen 78 X Marcinkowski 85 A Kielan 93 A Kielan 93 A Kielan 93

The marks mean that the data are agreement with our results within the values: 0;<7%, C; 7-15%, A;15-25%, and X; > 25%. *l: Revised with recent 17 value of 9.23 ± 9 from 8 ± 1. The following nine reactions, which had been previously measured at one energy, have been obtained in the energy range of 13.4-14.8 MeV for the first time; Srsr (n, p)m, 104pd (n, p)m, lOSpd (n, p)m, lOSpd(n' p)g, lO7Ag (n, p)m, ll6Cd (n, p)g, ll9Sn (n, p)g and 12°Sn (n, p)ml, m2. TWO isomer states of 12°Sn (n, p) were measured separately. Comparison of our data with previous experimental data and evaluation is summarized in Table 2. The data of Ikeda et al. (1988) at FNS agreed with our results to within 7%. Seven of the eight reactions by Viennot et al. (1991) also showed reasonable agreement, within 25%. [In the case of the 66Zn (11, p) reaction, the data of Viennot et al. (1991) agree with our data when their data were revised using recent values for the y-ray intensity (Miyahara et al., 1993).] Most of the data obtained previously at multi-point-energies have shown reasonable agreement within 25%. Seven of the ten evaluation data of JENDL-3 are in agreement with our results to within 25%, but three evaluations deviate by more than 25%. The evaluations of ENDF/B-VI are scarce, so a definite conclusion is not clear.

4. CONCLUSION The 28 (n, p) activation cross-section leading to short-lived nuclei at neutron energies of between 13.4-14.9 MeV was obtained by activation methods. Our results have improved the reliability of cross-sections and have given information on the partial excitation function about 14 MeV. From comparisons of our data with those from FNS all of data agree well to within 7%. Evaluation data of JENDL-3 are in agreement within 25%. However, the evaluations still need to be improved. The 17 reaction cross-sections obtained have not yet been evaluated. Those data need to be evaluated in order to improve reliability of the database by comparison with experimental results.

Measurement of (n,p) cross-sections

45

Acknowledgements--This work was performed under the contract between Nagoya University and Japan Atomic Energy Research Institute and partly supported by a grant-in-aid from the Ministry of Education, Japan. The authors wish to express their sincere thanks to the members of the JAERI Nuclear Data Center. They are also grateful to Prof. A. Takahashi for supporting this work. Messrs. H. Sugimoto, M. Datemichi and S. Yoshida are thanked for their operation of the accelerator.

REFERENCES

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