Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 49 (2016)

Peformance of a fast kicker magnet for Rare-RI Ring†H. Miura,∗1 Y. Abe,∗2 Z. Ge,∗2 K. Hiraishi,∗3 Y. Ichikawa,∗3 I. Kato,∗1 T. Moriguchi,∗3 D. Nagae,∗2 S. Naimi,∗2T. Nishimura,∗1 S. Omika,∗1 A. Ozawa,∗3 F. Suzaki,∗1,∗2 S. Suzuki,∗3 T. Suzuki,∗1 N. Tadano,∗1 Y. Tajiri,∗3Y. Takeuchi,∗1 T. Uesaka,∗2 M. Wakasugi,∗2 T. Yamaguchi,∗1 Y. Yamaguchi,∗2 and Rare-RI ring collaborators
A fast kicker magnet is indispensable for injectingbeams into the rare-RI ring individually1) . Therefore,
we developed a distributed-constant type fast kicker
magnet. The kicker magnet is equivalent to an electronic circuit that is a π-type LC circuit.
Based on the detailed simulations of the equivalent
electronic circuit of the prototype kicker magnet, we
optimized the inductance, capacitance, and mutual inductance. We used these simulation results to develop
a new kicker magnet. The new kicker magnet parameters are designed to be L = 100 nH and C = 350 pF
to improve impedance matching, and an additional capacitance of 2600 pF was attached to the entrance ofthe kicker magnet to prevent reﬂection.
We applied the search coil method to measure themagnetic ﬁeld. The result of the magnetic ﬁeld of thenew kicker magnet at 20 kV is shown in Fig.1. The
propagation time from a trigger signal input, whichcorresponds to 0 ns in Fig.1, until the peak of the kicker
magnet ﬁeld, is approximately 545 ns.
350
300
250
200
150
100
500-5000.015
0.010.005
0200 400 600 800 1000 1200 1400

∗2∗318202224 26 28 30 32
Charge Voltage[kV]34Fig. 2. Number of injected events by the plastic scintillation detector as a function of the charging voltage ofthe kicker magnet.

In June 2015, we carried out the ﬁrst commissioningof the rare-RI ring using a 78 Kr36+ beam with an energy of 168 MeV/nucleon. The kick angle of 11.4 mrad
is required for injection into the rare-RI ring. For thepresent beam condition, a magnetic ﬁeld of 434 G isrequired. Thus, the kicker power supply should becharged up to 26.6 kV.
We tested an individual injection method using thenew kicker magnet. To conﬁrm the injection of thebeam, a plastic scintillation counter was placed in thecentral orbit at the detector chamber after the next
straight section of the rare-RI ring. When the beamis kicked correctly, it is counted by the plastic scintillation counter. We measured the number of counts∗10.025
0.02

Fig. 1. Typical magnetic field of a new kicker magnet.

†by changing the charging voltage, as shown in Fig. 2.
This ﬁgure shows the relative injection eﬃciency because the width of the plastic scintillation counter issmaller than that of the acceptance of the ring.
We tested the ejection of the stored beam using thesame kicker magnet after 700 µs storage. A plastic
scintillation counter was placed at the exit of the ring.
We measured the number of events counted by theplastic scintillator by changing the ejection timing; thecharging voltage of the kicker magnet was 26.6 kV. The
result is shown in Fig. 3. This plastic scintillation has
suﬃcient width to cover the extractable acceptance ofthe ring. From this result, the kicker magnet has aﬂat top of approximately 100 ns because the durationuntil the extraction eﬃciency up to 90 % of the peakis approximately ± 50 ns.
The present result shows that the individual injection method and ejection was successfully performed.

Condensed from the article in Proceedings of HIAT2015,
Yokohama,Japan
Department of Physics, Saitama University
RIKEN Nishina Center
Institute of Physics, University of Tsukuba- 154 -

0.012
0.01
0.008
0.006
0.004
0.002
0150 200 250 300 350 400 450 500 550
ejection time[700000 + ns]

Fig. 3. Number of events counted by the plastic scintillation detector at the exit of the storage ring as a functionof ejection delay timing.

Reference1) Y. Yamaguchi et al., Phys. Scr. T166, 014056 (2015).