Neutron sensitivity of the endcap RPC modules in Belle detector

Abe, K.; Hoshi, Y.; Nagamine, T.; Neichi, K.; Onodera, K.; Takahashi, T.; Yamaguchi, A.; Yuta, H.

doi:10.1109/tns.2003.814571

Cited by 8 publications

(4 citation statements)

References 4 publications

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“…Neutrons are highly penetrating, difficult to shield, and often not simulated accurately by default Monte Carlo simulation codes. Neutrons degraded the KLM detector performance in Belle [74,75] and the DIRC detector performance in the BaBar Experiment [76]. With even higher beam currents and luminosity at SuperKEKB, neutrons from beam backgrounds are expected to be a critical issue at Belle II, as discussed in Section 10.4 of Ref.…”

Section: Neutron Background Measurementsmentioning

confidence: 99%

First measurements of beam backgrounds at SuperKEKB

Lewis

Jaeglé

Nakayama

et al. 2019

Nuclear Instruments and Methods in Physics Research Section A:

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The high design luminosity of the SuperKEKB electron-positron collider is expected to result in challenging levels of beam-induced backgrounds in the interaction region. Properly simulating and mitigating these backgrounds is critical to the success of the Belle II experiment. We report on measurements performed with a suite of dedicated beam background detectors, collectively known as BEAST II, during the so-called Phase 1 commissioning run of SuperKEKB in 2016, which involved operation of both the high energy ring (HER) of 7 GeV electrons as well as the low energy ring (LER) of 4 GeV positrons. We describe the BEAST II detector systems, the simulation of beam backgrounds, and the measurements performed. The measurements include standard ones of dose rates versus accelerator conditions, and more novel investigations, such as bunch-by-bunch measurements of injection backgrounds and measurements sensitive to the energy spectrum and angular distribution of fast neutrons. We observe beam-gas, Touschek, beam-dust, and injection backgrounds. As there is no final focus of the beams in Phase 1, we do not observe significant synchrotron radiation, as expected. Measured LER beam-gas backgrounds and Touschek backgrounds in both rings are slightly elevated, on average three times larger than the levels predicted by simulation. HER beam-gas backgrounds are on on average two orders of magnitude larger than predicted. Systematic uncertainties and channel-to-channel variations are large, so that these excesses constitute only 1-2 sigma level effects. Neutron background rates are higher than predicted and should be studied further. We will measure the remaining beam background processes, due to colliding beams, in the imminent commissioning Phase 2. These backgrounds are expected to be the most critical for Belle II, to the point of necessitating replacement of detector components during the Phase 3 (full-luminosity) operation of SuperKEB.

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Section: Neutron Background Measurementsmentioning

confidence: 99%

First measurements of beam backgrounds at SuperKEKB

Lewis

Jaeglé

Nakayama

et al. 2019

Nuclear Instruments and Methods in Physics Research Section A:

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“…As such, neutrons have proven to be a particularly pernicious background at B-factories. In previous experiments, neutrons degraded the KLM detector performance at Belle [7,8] and the DIRC detector performance in the BaBar Experiment [9]. Given the beam current and luminosity upgrades at Su-perKEKB, neutron backgrounds are expected to be a critical issue at Belle II.…”

Section: Introductionmentioning

confidence: 99%

First 3D vector tracking of helium recoils for fast neutron measurements at SuperKEKB

Hedges,

Vahsen,

Jaegle

et al. 2021

Preprint

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We present results from the first deployment of novel, high definition, compact gas Time Projection Chambers (TPCs) with pixel chip readout as part of the BEAST II beam background measurement project at SuperKEKB. The TPCs provide detailed 3D imaging of ionization from neutron-induced nuclear recoils in a helium and carbon dioxide target gas mixture at standard temperature and pressure. We present the TPC performance and the neutron backgrounds observed during the initial stage of collider commissioning. We find excellent electron background rejection, leading to background-free nuclear recoil measurements above 50 keV ee , despite the extreme high-background environment. We measure an angular resolution better than 20 • for recoil tracks longer than 1.7 mm, corresponding to an average ionization energy of approximately 100 keV ee . We also obtain the full 3D vector direction of helium recoils by utilizing charge profile measurements along the recoil axis, with a correct head/tail assignment efficiency of approximately 80%. With this performance, we present comparisons between measured and simulated event rates, recoil energy spectra, and directional distributions originating from beam-gas and Touschek beam losses at SuperKEKB. We utilize head/tail recognition to distinguish neutron components travelling with positive radial velocity in the Belle II coordinate system from those travelling in the opposite direction. Finally, we present a novel method of discriminating beam-gas interactions from Touschek beam losses that can eliminate the need for dedicated accelerator runs for background measurements. This method is still statisticslimited. However, future studies should be able to verify this method, which in turn could lead to neutron background analysis runs symbiotic with normal Belle II operation. The capabilities demonstrated here also suggest that high definition recoil imaging in gas TPCs is applicable to low energy, low-background experiments, such as directional dark matter searches.

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“…The extension of the rate capabilities can be achieved with the industrial glass electrodes, i.e. around 2 kHz cm −2 [4]. The glass-electrode RPCs are easy to handle and built on an industrial scale.…”

Section: Introductionmentioning

confidence: 99%

Simulation of the neutron response of a glass-resistive plate chamber in the energy range 10⁻¹⁰ MeV<E_n<10 GeV

2007

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The neutron sensitivity of a glass-resistive plate chamber (RPC) has been simulated using GEANT4 MC codes for the neutrons in the energy range 10 −10 MeV-10 GeV. The glass-RPC has many advantageous features such as high rate capability, it is easy to handle and can be built on an industrial scale. For an evaluation of their efficiency, a simulation test of the glass-RPC detectors has been performed in order to investigate their performance for neutrons detection. When compared to previous works on bakelite-RPC the results are comparatively higher. As the density of the glass electrode is higher than the bakelite electrode, relatively higher sensitivity results at higher neutron energies were obtained using these types of RPCs. For an isotropic neutron source using a GEANT4 Standard MC package, sensitivity, s n < 3.894 × 10 −2 at <10 GeV by double-gap glass-RPC has been observed. For the same neutron source with a GEANT4 Low MC package, double-gap glass-RPC sensitivity, s n < 4.042 × 10 −2 at <10 GeV has been measured. Similar but lower simulation results of the RPC detector have been observed for parallel neutron source configurations. The obtained simulated results were applied to the large hadron collider (LHC)/(CMS) compact muon solenoid radiation environment both in the endcap and barrel regions. The average sensitivities, expected hit rates in those regions were estimated. Additionally, a comparison between the present glass-RPCs with the previous bakelite-RPCs neutrons simulation results has been performed.

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Neutron sensitivity of the endcap RPC modules in Belle detector

Cited by 8 publications

References 4 publications

First measurements of beam backgrounds at SuperKEKB

First measurements of beam backgrounds at SuperKEKB

First 3D vector tracking of helium recoils for fast neutron measurements at SuperKEKB

Simulation of the neutron response of a glass-resistive plate chamber in the energy range 10⁻¹⁰ MeV<E_n<10 GeV

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Neutron sensitivity of the endcap RPC modules in Belle detector

Cited by 8 publications

References 4 publications

First measurements of beam backgrounds at SuperKEKB

First measurements of beam backgrounds at SuperKEKB

First 3D vector tracking of helium recoils for fast neutron measurements at SuperKEKB

Simulation of the neutron response of a glass-resistive plate chamber in the energy range 10−10 MeV<En<10 GeV

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Simulation of the neutron response of a glass-resistive plate chamber in the energy range 10⁻¹⁰ MeV<E_n<10 GeV