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2024
Luca Moleri (Weizmann Institute of Science)
Gaseous radiation detectors. The case of Thin Gap Chambers and Thick Gaseous Electron Multipliers

Experiments in high energy physics, particle astrophysics and imaging applications in the medical and homeland security field, all require instruments capable of detecting ionizing radiation and produce precise measurements of events' energy, position and time. Since the very beginning of the fundamental particle physics' era, gases have been used as interaction media for particle detection. After about a century gaseous detectors are still at the heart of most high energy physics experiments, providing a cost effective way to cover very large areas. At the Weizmann Institute of Science in Israel we are continuing a decades' long tradition that started with the group of George Charpak at CERN with the development of multi-wire proportional chambers (MWPC) and continues with modern micro-pattern gaseous detectors (MPGD) driven by the continuous technological developments in the industry. In the era of digital electronics and quantum computers, the tiny analog signal produced by ionization and charge drift in a gas is still an indispensable tool for investigating the innermost laws of matter. We propose an insight into the physics of gaseous detectors through the particular case of the experience at the Weizmann Institute of Science in Israel, including Thin Gap Chambers for the muon trigger system of the ATLAS experiment at CERN [1,2] and the development of new detector concepts based on Thick Gas Electron Multipliers (THGEM) [3].

  • [1] https://atlas.cern/Discover/Detector/Muon-Spectrometeri
  • [2] Nagai, K., 1996. Thin gap chambers in ATLAS. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 384(1), pp.219-221.
  • [3] Bressler, S., Moleri, L., Jash, A., Tesi, A. and Zavazieva, D., 2023. The Thick Gas Electron Multiplier and its derivatives: Physics, technologies and applications. Progress in particle and nuclear physics, p.104029.
  • 2023
    Massimiliano Fiorini and Roberto Calabrese (INFN Ferrara)
    The LHCb RICH detector: past, present and future

    Present about the original RICH of Run1-2 (using HPDs), the present RICH for Run3-4 (using MaPMTs), and ideas on a future upgrade of the RICH with new photodetectors for operation at the high-luminosity LHC


    Abner Soffer (Tel Aviv Univ.)
    Searching for supersymmetry with R-parity violation and a light neutralino at B factories

    Supersymmetry is a theoretically attractive extension of the standard model. Supersymmetric particles with masses in the 100-1000 GeV range were motivated by the “hierarchy problem" of the standard model, and their expected discovery constituted a strong motivation for construction of the LHC. While such particles have not been discovered, wide regions of supersymmetry parameter space are still allowed, prompting development of new theoretical and experimental ideas. In particular, Belle II has a unique sensitivity to supersymmetry with a GeV-scale neutralino when a symmetry called R-parity is violated in certain ways. In this talk I will discuss the theoretical background, describe existing limits on the parameters of such a model, and detail the searches we propose to conduct at Belle II.

    2022
    Peter Krizan (KMI/Jožef Stefan Institute)
    Instrumentation for advances in ET medical imaging

    Positron emission tomography (PET) is an in-vivo method for imaging of biological processes via detection of pairs of 511 keV annihilation gamma rays. A recent paradigm shift in medicine from the treatment of obvious diseases to an early diagnosis and prevention is leading to more stringent requirements on PET sensitivity, while the advances in the targeted radionuclide therapy and theranostics require a need for more widespread and accurate PET. Promising advances in the instrumentation required for this evolution come again from particle physics. In the seminar we will discuss two innovation areas, flexible limited angle PET scanners and scanners based on Cherenkov radiation.


    音野 瑛俊氏 (九州大学・先端素粒子物理研究センター・助教)
    FASER実験 - LHCの衝突点前方における新物理の開拓

    FASER実験はLHCの衝突点前方の480 m地点に検出器を配置し、MeVからGeV領域の未知粒子探索とTeV領域のニュートリノ研究を目的とする。 原子核分野や宇宙線分野へも新たな知見が得られることが期待されている。 LHCはRun 3を開始し、FASER実験はデータ取得を開始した。本セミナーではその最新状況を紹介する。


    Abner Soffer (Tel Aviv Univ.)
    Searching for long-lived particles at LHC and B factories

    Long-lived particles are predicted by many extensions of the standard model. Particles that fly a measurable distance before decaying inside the detector produce a clear experimental signature that provides very efficient background suppression. In this talk I will describe recent work in this area. This will include a search for a heavy neutral lepton (HNL) at ATLAS, an HNL search at Belle that covers a different mass range, and several proposed searches of long lived particles in additional scenarios.


    Dalziel J. Wilson (U. Arizona)
    Optomechanical Dark Matter Detection

    Recently it has been proposed to search for dark matter using mechanical sensors, exploiting the fact that all dark matter candidates couple to the size or position of atoms. While focus has been directed towards analyzing signal from gravitational wave detectors and equivalence principle tests, a unique opportunity has emerged to develop compact detectors based on cavity optomechanical systems, which have recently achieved force measurements at the quantum limit. I'll discuss this concept from an experimentalist's perspective, highlighting a proposal to search for vector dark matter with optomechanical accelerometers. In this context, our lab is developing a new generation of ultra-sensitive accelerometers based on centimeter-scale silicon nitride membranes.


    Swati Singh (U. Delaware)
    Mechanical sensors for exploring the dark sector

    When properly engineered, simple quantum systems such as harmonic oscillators or spins can be excellent detectors of feeble forces and fields. Following a general introduction to this fast growing area of research I will focus on using optomechanical systems as sensors of weak acceleration and strain fields. Ultralight dark matter coupling to standard model fields and particles would produce a coherent strain or acceleration signal in an elastic solid. I will discuss the feasibility of searching for this signal using various optomechanical systems. I will also show that current mechanical systems have the sensitivity to set new constraints on scalar field candidates for dark energy. Finally, I will briefly overview the promise of quantum noise limited detectors in the search for beyond the standard model physics.

    2021
    Akash V. Dixit (U. Chicago)
    Searching for Dark Matter with Superconducting Qubits

    Detection machanisms for low mass bosonic dark matter candidates, such the axion or hidden photon, leverage potential interactions with electromagnetic fields, whereby the dark matter (of unknown mass) on rare occasion converts into a single photon. Current dark matter searches operating at microwave frequencies use a resonant cavity to coherently accumulate the field sourced by the dark matter and a near standard quantum limited (SQL) linear amplifier to read out the cavity signal. To further increase sensitivity to the dark matter signal, sub-SQL detection techniques are required. Here we report the development of a novel microwave photon counting technique and a new exclusion limit on hidden photon dark mater. We operate a superconducting qubit to make repeated quantum non-demolition measurements of cavity photons and apply a hidden Markov model analysis to reduce the noise to 15.7 dB below the quantum limit, with overall detector performance limited by a residual background of real photons. With the present device, we perform a hidden photon search and constrain the kinetic mixing angle to epsilon < 1.68×10-15 in a band aroudn 6.011 GHz (24.86 μeV) with an integration time of 8.33 s. This demonstrated noise reduction technique enables future dark matter searches to be sped up by a factor of 1,300. By coupling a qubit to an arbitrary quantum sensor, more general sub-SQL metrology is possible with the techniques presented in this work.


    Yasuhito Sakaki (KEK)
    Fixed target experiments using electron and positron beams

    Now that new heavy particles have not been found at the LHC, focusing on light and weakly interacting new particles is one direction to go. Fixed target experiments using accelerators play a part in this. I will explain the basics of the phenomena in fixed target experiments, and how to calculate the number of signal on a target induced by e+ e- beams. Trends in some fixed-target experiments will be introduced. I will discuss some ideas for fixed target experiments at the ILC and KEK.

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