PRACTICAL USE NEUTRON RADIOGRAPHY
WITH BABY CYCLOTRON
Y.Nozaki, N.Saito, Y.Fukushima, T.Nakamura
J .Furuta,* E.Hiraoka,* J .Sekita**, A.Murakoshi**,T.Yamada***, S.Wakasa***, T.Tanaka***, H.Yoshida***National Space Development Agency of Japan, Radiation
Center of Osaka pref*., Tesco Corporation**, The Japan
Steel Works,LTD***.
Abstract
A fundamental test for Neutron Radiography Testing(NRT) were performed by Baby Cyclotron and a newly
manufactured moderator and a collimetor !1•21 In the case ofcollimat\01'1 ratio -L/D=67. 3, 2. 5X10° n/ cm2• sec. thermal neutron
flux were obtained at the exit of the collimator by proton
It shows that the Baby Cyclotron has
beam of 16 MeV, 50 uA.
the possibility of practical use as a neutron generato-r
for NRT.
Experimentand Results

The specifications of Baby Cyclotron and the experimental layout are shown in Table 1 and Fig.1, respectively.
a) .Measurement of l dose r.ate
r-ray spectrum at the exit of the collimator wasThemeasured by the Nai(Tl) scintillation probe.
result showed that energy distribution extended to widerange and ~-rays were mainly induced in the vicinity ofthe target. Bismuth disc was placed in front of thecollimator in order to reduce r-ray and r dose rate at
the exit of the collimator were measured by TLD invarious cases. The results are shown in Table 2.
b) Measurement of thermal neutron flux
Thermal neutron flux at the exit of the collimator
was measured by Au foil activation method in variouscases. The results are also shown in Table 2.
n/~ ratio,which is the figure of merit of the imagefrom Table 2. The results arequality, was obtained(In general,n/r)l.OX 10s is desirable.)shown in Table 3.

c) Imaging test
Imaging tests were performed in various cases. In thecase of L/D=67.3 and l6MeV proton beam,the best resultof R value=lO of the ASTM indicator was obtained.

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The following results became clear rrom the experiments.
i) The neutron flux generated by 16 MeV proton isapproximately five times larger than that of 8 MeV
deuteron.
ii) Thermal neutron flux at the exit of the collimator(L/D=67.3) was 2 x 10 5 n/c~.sec. in the case of 16 MeV
50 pA proton.
iii) n/0 ratio was between 3.0 x lOs and 2.0 x 10 6 •iv) R value=lO of the ASTM indicator was obtained.
that Baby Cyclotron has enoughAbove results show
ability for practical use for NRT.
Referencesl)N.D.Tyufyakov and A.S.Shtan,Principle of Neutron Radiography,Atomzdat Publisher,Moscow,(1975)
2)E.Hiraoka et al~J.Non-Destructive Inspection,27(1978)
Table lSpecifications ofBaby Cyclotron~RC 107 AParticlepdpd

Energy(MeV)

II7.5

168Thermal Neutron Flux
dose rateandTable 2oProton

ProtonDeuteron

Energy( MeV)

16117 .s

Beam Current().lA)

soso502S252523

2323

Particle

BC 16 B.
".

Para!'!'in(mm)~CurrenHJlAl

50

50

5050

Bismu'th(mm)•. 3 X~lO. 1=~ro.2(t7~=~ .3);

to 7

t.S X 10 7

8.3 X 10'

1.e X to'

2.S X 10 5';)

~ ~:;iOlo.3(No.4~:·ti;!~~. ~)~~ ~0. (ti;~!;. :;)..·]~
-5

3.0 X

2 .) X 10'
2.0 X 10 3:-.lo.4

2 .t

No.5

2. 4

Particle

Energy(MeV)

Proton,.

Protont6. Proton

16(KA'n::R(AI.)
lloder•tor;

Front llode.-.tar;

Fig. 1~perimental

Polyethylen ..
P:trat'fln
or IIISIIII.Ith

Layout-160-ration/ 0Table 3["t---.C.U.""t2~

3 ...

2. 5

No.J

"~to 8~~;:~ 7 . J 1.5 X to'~lI

II

L(mm)

L/0n/r ratio

820

27.3

2.2 X 10 61870

62.3

3.6 X lOS

2020

67-.3

3.0 X 10~