ETL 4UH-HC PELLETRON
K.Kudoh, T .1Ushijima, I.Nashiyama, H. Watanabe
H.Sekiguchi, M.Kageyama, T.Kinoshita, T.Michikawa andE.Teranishi
N .Kobayashi,Electrotechnical Laboratory,., ~Tsukuba, Ibarakil. Introduction

A 4MV electrostatic accelerator of single-ended type (4UH-HC
Pelletron of NEC) was installed at ETL at the beginning of thisAssembling and beam tests with full specifications- wereyear.
successfully completed during the first half period of the year.
At present, normal operations and application works are put intopractice.
This accelerator is designed for high-current beam and nanosecond pulsed beam operation for the purpose of monoenergetic
neutron production, fine beam analyses and ion beam irradiation.
2. Accelerator Description and PerformanceThis accelerator is a horiz9ntal-type single-ended accelerator
equi:'pped with 4·column units, ·a rotat..ing sh~ft for power eJ:eneration at the high-voltage terminal, 4 metal-pellet chains (2 pairs)
to deliver maximum current of 500 pA and 60 optical fibers forcommunications between the tank base and the high-voltage terminal(ion source control and read-back).
Two types of ion source can be mounted - (A) duoplasmatron ion
source for light-ion and pulsed proton beam production and (B) anoscillating electron type (Danfysik 910) ion source for heavy-ion
production.
A mini-computer (NOVA 4/X 128 kB, 12.5 MB disc) is equipped forcontrolling and monitoring of a NMR gaussmeter, a switching magnetand (in future) terminal electronics.
HighPerformances of this accelerator is shown in Table 1.
current proton beam was monitored with a Faraday cup located at
The characteristics of
5 m downstream from the switching magnet.
pulsed proton beam were measured by detecting j radiation-from AlIn Fig.l is shown the time spectrum of the 4 MeV ·+p reaction.
pulsed proton beam obtained by this method.
The energy calibration and the energy stability test of theproton beam have been made by observing the threshold energy o.f
the monoenergetic neutron production by 7 Li(p,n)7Be and 4~Sc(p,n)
In Fig.2, neutron yields= 1.8804 MeV and 2.908 MeV).
~STi (Eas a f~thion of incident proton energy are plotted in the ca~e of
Li+p (target thickness of 124 yg/cm on Ta).

3. Application Studies
As already reported 1 ), establishment of neutron fluence standards and experimantal studies using ion beams are performed atETL.
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ETL is to participate in the internation al intercompa rison ofmonoenerge tic neutron fluence standards (En = 144-, 565-keV, 2.5-,5.0-, 14.8-MeV).
Absolute fluences of neutrons produced by 7 Li(p,n)7Be and T(p,n) 3 He are measured with proton-rec oil detectors. In
Fig.3 is shown the output pulse-heigh t distributio n of methanefilled proportiona l counter in the Gase of 400 keV monoenerge ticneutrons.
Irradiation studies of CTR wall materials - refractory metals
and low Z coating materials - are carried out by applying ion beam
analysis methods - RBS, nuclear reaction and electron spectroscop yo
Referenc-e1) Proceedings of the 3rd Symposium on Accelerator Science andTechnology. p.287 (1980).
Table 1. Performance s of ETL 4UH-HC Pelletron
Maximum column voltage:t-laximum beam energy
Maximum beam current
Voltage stability
Pulsed proton beam

4.4 MV
4.0 MeV (proton)>100 JAA (proton)+ 2 kV
FWHM <2 nsPeak current 1 mAAl(p,'l)

NE213

::

FIIHM 2.37 ns: - (nomina~)
1002040

UME (ns)

Fig.l Time spectrum of pulsed proton
beam obtained by y detection from Al+p.

LU' Thiele Target

7Li (p,n) 7:se

CH4 prop. counter..

.§., -OL-~~~--~--~--~---

1879

1880

1881

1882

1883

1884

BP (kel')Fig.2 Neutron yields from 7 Li(p,n) 7 Be asa function of incident proton beam energy.

500

1000

CHAIIIIEL IIUHllER

Fig.3 Output pulse-height distribution o~CH 4 proportional counter by 400 keV neutrons.
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