Performance of a resonant Schottky pick-up in the ... · Performance of a resonant Schottky pick-up...
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Ⅱ-9. Instrumentation - 179 - RIKEN Accel. Prog. Rep. 49 (2016) Performance of a resonant Schottky pick-up in the commissioning of Rare RI Ring † F. Suzaki, ∗1,∗2 Y. Abe, ∗1 Z. Ge, ∗1 K. Hiraishi, ∗3 Y. Ichikawa, ∗3 I. Kato, ∗2 H. Miura, ∗2 T. Moriguchi, ∗3 D. Nagae, ∗1 S. Naimi, ∗1 T. Nishimura, ∗2 S. Omika, ∗2 A. Ozawa, ∗3 S. Suzuki, ∗3 T. Suzuki, ∗2 N. Tadano, ∗2 Y. Tajiri, ∗3 Y. Takeuchi, ∗2 T. Uesaka, ∗1 M. Wakasugi, ∗1 T. Watanabe, ∗1 K. Yamada, ∗1 T. Yamaguchi, ∗2 Y. Yamaguchi, ∗1 J. Zenihiro, ∗1 and Y. Yano ∗1 The Rare RI Ring is a storage ring dedicated to the measurement of the masses of unstable nuclei to study their nuclear structure and nucleosynthesis 1) . We em- ploy the isochronous mass spectrometry method aim- ing at a relative mass precision of 10 −6 . For such high- precision measurement, reaching the isochronous con- dition in the ring up to a precision of 10 −6 is essential. As a monitor for the tuning of the isochronous field, we adopt a resonant Schottky pick-up. Figure 1 a) shows the resonant Schottky pick-up installed in the ring. When the beam passes through the resonant Schot- tky pick-up, an electromagnetic field is induced in the resonant cavity. Figure 1 b) shows the magnetic field induced at the resonance frequency f res . The change of magnetic flux is detected by a pick-up loop inside the cavity. Similar resonant Schottky pick-ups have been used at GSI 2) in Germany and IMP 3) in China. From the results of an offline test, we obtained f res = 171.43 MHz, shunt impedance R sh = 161 kΩ, and unloaded quality factor Q 0 = 1880 4) . In June 2015, we commissioned the Rare RI Ring using a Kr beam with an energy of 168 MeV/u. In the commissioning, we successfully observed the signals of a single Kr ion in the Schottky spectrum, as shown in Fig. 2. The upper part of Fig. 2 is a spectrogram of Kr. In this plot, the horizontal and vertical axes are the resonance frequency and time, respectively. The frequency shift is considered to be caused by the mo- mentum change due to the interactions with the resid- ual gas in the ring. The vacuum was still of the order of 10 −5 Pa without the baking procedure. The lower part of Fig. 2 is a zoomed FFT spectrum in a frame of 32 ms. The frequency width is 224 Hz at FWHM; therefore, the frequency resolution is 1.29×10 −6 . The measured signal power is P = −68.9 dBm, where P is obtained by integrating the peak in the Schottky spectrum after subtracting thermal noise background. For comparison, we calculated the expected signal power P cal by using the following equation which rep- resents the signal power of a single ion with charge q 2) : P cal =1/8(qef ) 2 R load , where e = elementary charge, f = revolution frequency, and R load is calculated from the equation R load = R sh /Q 0 × Q load . Taking into † Condensed from the article in Proceedings of HIAT2015, Yokohama, Japan ∗1 RIKEN Nishina Center ∗2 Department of Physics, Saitama University ∗3 Institute of Physics, University of Tsukuba account the gains of two amplifiers and transmission losses, P cal = -66.1 dBm. The observed Schottky sig- nal power P is in good agreement with the expected P cal . In conclusion the performance of the resonant Schottky pick-up is sufficient in terms of sensitivity and resolution. Resonant Cavity Beam Fig. 1. a) A photograph of the resonant Schottky pick-up. ɹ b) Magnetic field in the resonant cavity induced by the beam. Fig. 2. Upper: A spectrogram of a single 78 Kr ion. ɹɹ Lower: A zoomed FFT spectrum in a frame of 32 ms. References 1) Y. Yamaguchi et al., Nucl. Instrum. Methods Phys. Res. B 317, 629 (2013). 2) F. Nolden et al., Nucl. Instrum. Methods Phys. Res. A 659, 69 (2011). 3) J. X. Wu et al., Nucl. Instrum. Methods Phys. Res. B 317, 623 (2013). 4) F. Suzaki et al., JPS Conf. Proc. 6, 030119 (2015). a) b) Resonant Cavity
Transcript of Performance of a resonant Schottky pick-up in the ... · Performance of a resonant Schottky pick-up...
Ⅱ-9. Instrumentation
- 179 -
RIKEN Accel. Prog. Rep. 49 (2016)
Performance of a resonant Schottky pick-up in the commissioning ofRare RI Ring†
F. Suzaki,∗1,∗2 Y. Abe,∗1 Z. Ge,∗1 K. Hiraishi,∗3 Y. Ichikawa,∗3 I. Kato,∗2 H. Miura,∗2 T. Moriguchi,∗3
D. Nagae,∗1 S. Naimi,∗1 T. Nishimura,∗2 S. Omika,∗2 A. Ozawa,∗3 S. Suzuki,∗3 T. Suzuki,∗2 N. Tadano,∗2
Y. Tajiri,∗3 Y. Takeuchi,∗2 T. Uesaka,∗1 M. Wakasugi,∗1 T. Watanabe,∗1 K. Yamada,∗1 T. Yamaguchi,∗2
Y. Yamaguchi,∗1 J. Zenihiro,∗1 and Y. Yano∗1
The Rare RI Ring is a storage ring dedicated to themeasurement of the masses of unstable nuclei to studytheir nuclear structure and nucleosynthesis1). We em-ploy the isochronous mass spectrometry method aim-ing at a relative mass precision of 10−6. For such high-precision measurement, reaching the isochronous con-dition in the ring up to a precision of 10−6 is essential.As a monitor for the tuning of the isochronous field, weadopt a resonant Schottky pick-up. Figure 1 a) showsthe resonant Schottky pick-up installed in the ring.When the beam passes through the resonant Schot-tky pick-up, an electromagnetic field is induced in theresonant cavity. Figure 1 b) shows the magnetic fieldinduced at the resonance frequency fres. The change ofmagnetic flux is detected by a pick-up loop inside thecavity. Similar resonant Schottky pick-ups have beenused at GSI2) in Germany and IMP3) in China. Fromthe results of an offline test, we obtained fres = 171.43MHz, shunt impedance Rsh = 161 kΩ, and unloadedquality factor Q0 = 18804).
In June 2015, we commissioned the Rare RI Ringusing a Kr beam with an energy of 168 MeV/u. In thecommissioning, we successfully observed the signals ofa single Kr ion in the Schottky spectrum, as shown inFig. 2. The upper part of Fig. 2 is a spectrogram ofKr. In this plot, the horizontal and vertical axes arethe resonance frequency and time, respectively. Thefrequency shift is considered to be caused by the mo-mentum change due to the interactions with the resid-ual gas in the ring. The vacuum was still of the orderof 10−5 Pa without the baking procedure. The lowerpart of Fig. 2 is a zoomed FFT spectrum in a frameof 32 ms. The frequency width is 224 Hz at FWHM;therefore, the frequency resolution is 1.29×10−6. Themeasured signal power is P = −68.9 dBm, where Pis obtained by integrating the peak in the Schottkyspectrum after subtracting thermal noise background.For comparison, we calculated the expected signalpower Pcal by using the following equation which rep-resents the signal power of a single ion with charge q2):Pcal = 1/8(qef)2Rload, where e = elementary charge,f = revolution frequency, and Rload is calculated fromthe equation Rload = Rsh/Q0 × Qload. Taking into
† Condensed from the article in Proceedings of HIAT2015,Yokohama, Japan
∗1 RIKEN Nishina Center∗2 Department of Physics, Saitama University∗3 Institute of Physics, University of Tsukuba
account the gains of two amplifiers and transmissionlosses, Pcal = -66.1 dBm. The observed Schottky sig-nal power P is in good agreement with the expectedPcal. In conclusion the performance of the resonantSchottky pick-up is sufficient in terms of sensitivityand resolution.
Resonant
Cavity Beam
Fig. 1. a) A photograph of the resonant Schottky pick-up.
b) Magnetic field in the resonant cavity induced by
the beam.
Fig. 2. Upper: A spectrogram of a single 78Kr ion. Lower: A zoomed FFT spectrum in a frame of 32 ms.
References1) Y. Yamaguchi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 629 (2013).2) F. Nolden et al., Nucl. Instrum. Methods Phys. Res. A
659, 69 (2011).3) J. X. Wu et al., Nucl. Instrum. Methods Phys. Res. B
317, 623 (2013).4) F. Suzaki et al., JPS Conf. Proc. 6, 030119 (2015).
a) b)
Resonant Cavity
