Bucking coil implementation on PMT for active canceling of magnetic field

Abstract

Aerogel and waterČerenkov detectors were employed to tag kaons for a Λ hypernuclear spectroscopic experiment which used the (e, e ′ K + ) reaction in experimental Hall C at Jefferson Lab (JLab E05-115). Fringe fields from the kaon spectrometer magnet yielded ∼ 5 Gauss at the photomultiplier tubes ( PMT ) for these detectors which could not be easily shielded. As this field results in a lowered kaon detection efficiency, we implemented a bucking coil on each photomultiplier tubes to actively cancel this magnetic field, thus maximizing kaon detection efficiency.

Development of water Čerenkov detector for on-line proton rejection in Ξ− hypernuclear spectroscopy via the (KGogami1, Amano2, Kanatsuki3 et al. 2016Nuclear Instruments and Methods in Physics Research Section A: Self Cite5060View full textAdd to dashboardCite

“…We measured the magnetic field around positions where PMTs of the waterČerenkov detector will be, and found that there is about B y = 5 G at maximum *2 . In the study of [6], the gain of a PMT (Hamamatsu H7195), which is the similar PMT type to ours (Hamamatsu H11284-100UV), is reduced by 60% in the case that the magnetic field of B y = 5 G is yielded on the PMT. Therefore, the magnetic field on the PMTs should be suppressed in order to avoid a deterioration of the proton-rejection power which is caused by PMT-gain reductions.…”

“…Therefore, the magnetic field on the PMTs should be suppressed in order to avoid a deterioration of the proton-rejection power which is caused by PMT-gain reductions. For the waterČerenkov detector in S-2S, we plan to adopt the bucking coil method which was proven to work to recover the PMT gain against the similar strength of magnetic field (B y ≃ 4-6 G) in an experiment of Λ hypernuclear spectroscopy with the (e, e ′ K + ) reaction [6].…”

“…A waterČerenkov detector was used in experiments of Λ hypernuclear spectroscopy with the (e, e ′ K + ) reaction at Jefferson Lab (JLab) [6]. There are accumulated studies about the waterČerenkov detector in the (e, e ′ K + ) experiment at JLab [11], and our design and choices of materials for a prototype were inspired by them [12].…”

“…Background-particle suppression withČerenkov detectors was well established in past Λ hypernuclear experiments in a similar momentum range [4][5][6]. In the J-PARC E05 experiment, background-particle suppression is also designed to be performed with a combination of Cerenkov detectors.…”

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“…Then, the capability of on-line particle identification by theČerenkov detectors would be deteriorated. In order to ease the stray-magnetic field on PMTs, we are going to use both magneticfield shields and bucking coils [22]. We tested an implementation of the bucking coil on a PMT (Hamamatsu H11284-100UV [23]) which will be used for the waterČerenkov detector.…”