IV. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 54 (2021)

RIKEN Accel. Prog. Rep. 54 (2021)

Operation of the Pelletron tandem accelerator
T. Ikeda,∗1 M. Hamagaki,∗1 and H. Sato∗1Ion beams with an energy range of MeV are available
from the tandem accelerator (Pelletron 5SDH-2, 1.7 MVmax.) in the Nishina R&D Building, which is managed
by the Detector Team of RNC. This accelerator is also
registered as joint-use equipment in Wako campus formaterial analysis. As shown in the configuration of theaccelerator and beam lines (Fig. 1), two ion sources areavailable. One is the RF charge-exchange ion source,called Alphatross, for experiments using He ion beams.
The other is the Source of Negative Ions by Cesium Sputtering (SNICS), which can generate almost all other ions.
Thus far, ion species of H, He, Li, B, C, N, O, Si, Ti, Ni,Cu, and Au have been accelerated at 0.5–1.7 MV.
There are four beam lines named BL-E/Wnn (nn denotes the bending angle). In 2020, BL-E15 was restarted
for a user group in the field of material science to perform the analysis of Rutherford backscattering (RBS)
spectrometry. In the west side, BL-W15 (multipurposeline) was used for a micrometer-sized ion beam based on
glass capillary optics with an end window. This was forhorizontal microbeam irradiation experiments. The irradiation port was developed to have a simple connection
to the BL-W15 line. It took a few hours to mount themicrobeam port, including the vacuum pumping. At theend of 2020, BL-W30 was under construction for newmicrobeam irradiation studies of the biological samples
in air or solution.
From January 1 to December 31, 2020, the total machine time (MT) including a machine study was only

Fig. 1. Pelletron tandem accelerator and beam lines in theNishina R&D Building.

Fig. 2. (a) Apparatus for the RBS spectrometry connectedto the Pelletron accelerator. (b) Online analysis.
∗1

RIKEN Nishina Center

Table 1. Beam conditions and experiments conducted in thetandem accelerator.
Ion

Energy[MeV]

H+He2+

2.0–3.0
2.28

14Beam current
Operation
Experiment time [days]
[pnA]
1–120
0.25–5

Irradiation
RBS

84

Table 2. Approved conditions at the RIKEN Pelletron.
Ion

Maximum Energy

Ion

Maximum Energy

HHeLi/Be

3.5 MeV
5.1 MeV
6.8 MeV

BCother

10.2 MeV
12 MeV
0.6 MeV/nucleon

12 days, where the condition test of the ion sources isnot included. In addition to the total MT, development
activities were suppressed in 2020.
The ion species accelerated in this year were the lightions H+ and He2+ with energies ranging from 2.0 to3.0 MeV, as summarized in Table 1. The RBS experiments always used the energy of 2.28 MeV, following
convention. Points 1–6 below list the studies that used
the beam lines, along with the number of days of MT.
All the studies, including those with zero days of MT,
were routine experiments before 2020.
(1) Microbeam performance study with H ions using
glass capillaries at BL-W15 and W301,2) (7 days)(2) Microbeam (He ion) irradiation for single cells at
BL-W303) (0 days)(3) RBS/ERDA experiments using carbon ions (4days)(4) Educational experiment of proton capture by carbon/boron nucleus for Nishina School (0 days)(5) Development of charged-particle/gamma-ray detector to be used for RIBF experiments (0 days)(6) Other development using protons (1 day)
The maximum energies of accelerated ions are summarized in Table 2. Since 2019, the regulation of the maximum energy of carbon ions was changed from 7.2 MeV
to 11.9 MeV, where 12 C6+ is accelerated with the fullvoltage of 1.7 MV.
A commercial RBS apparatus (Charles Evans and Associates Model RBS-400) is shown in Fig. 2(a). A goniometer to rotate the sample is fixed inside the chamber,which is in a vacuum level of the order of 10−7 Torr. TheHe2+ beam intensity was less than 10 nA. Improvementsin the vacuum level and beam intensity are in progress.
References

1) T. Ikeda et al., Nucl. Instrum. Methods Phys. Res. B 470,42 (2020).
2) T. Ikeda, Quantum Beam Sci. 4, 22 (2020).
3) T. Ikeda et al., RIKEN Accel. Prog. Rep. 53, 215 (2020).

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