muCool: A novel low-energy muon beam for future precision experiments

Experiments with muons ($\mu^{+}$) and muonium atoms ($\mu^{+}e^{-}$) offer several promising possibilities for testing fundamental symmetries. Examples of such experiments include search for muon electric dipole moment, measurement of muon $g-2$ and experiments with muonium from laser spectroscopy to gravity experiments. These experiments require high quality muon beams with small transverse size and high intensity at low energy. At the Paul Scherrer Institute, Switzerland, we are developing a novel device that reduces the phase space of a standard $\mu^{+}$ beam by a factor of $10^{10}$ with $10^{-3}$ efficiency. The phase space compression is achieved by stopping a standard $\mu^{+}$ beam in a cryogenic helium gas. The stopped $\mu^{+}$ are manipulated into a small spot with complex electric and magnetic fields in combination with gas density gradients. From here, the muons are extracted into the vacuum and into a field-free region. Various aspects of this compression scheme have been demonstrated. In this article the current status will be reported.Comment: 8 pages, 5 figures, TCP 2018 conference proceeding

Designing the system to measure the depth-dose profile of a proton beam using CsI(Tl) scintillator

In this work, the standard CsI(Tl) scintillator was used to determine the characteristics of a proton beam. By irradiating the scintillator with a proton beam, it was able to subsequently measure the emitted light using a spectrometer. This work presents the dose response of a scintillator and its use to measure the depth-dose profile of a proton beam. The measurement of the dose response showed that the emission light of the scintillator depended on the total dose of the proton beam. For the design of the depth-dose measurement, the setup of the water phantom included a scintillator and a water tank. The depth-dose profile was determined through varying the water depth at various positions along the path of the proton beam until the end of the Bragg peak region. To compare the measured depth-dose profile, the deposited energy was simulated and fitted Birks constant for collecting quenching. Furthermore, the recommended measurement design suggested using a thin scintillator, as it resulted in a narrower shape of the depth-dose profile. Based on experiment and simulation data, a standard CsI(Tl) scintillator was promising for determining the characteristic proton beam.Comment: 10 pages, 7 figures, and 1 tabl

Development of wide range photon detection system for muonic X-ray spectroscopy

We have developed a photon detection system for muonic X-ray spectroscopy. The detector system consists of high-purity germanium detectors with BGO Compton suppressors. The signals from the detectors are readout with a digital acquisition system. The absolute energy accuracy, energy and timing resolutions, photo-peak efficiency, the performance of the Compton suppressor, and high count rate durability are studied with standard $\gamma$-ray sources and in-beam experiment using $^{27}\mathrm{Al}(p, \gamma){}^{28}\mathrm{Si}$ resonance reaction. The detection system was demonstrated at Paul Scherrer Institute. A calibration method for a photon detector at a muon facility using muonic X-rays of $^{197}$Au and $^{209}$Bi is proposed

Study of imaging system in proton computed tomography with data acquisition from a monolithic active pixel sensor

Abstract The first proton therapy system in Thailand has been installed at King Chulalongkorn Memorial Hospital (KCMH) since 2019. Apart from its clinical usage, Suranaree University of Technology (SUT) has initiated the collaborative research work with KCMH to explore a possibility of developing a proton computed tomography (pCT) prototype. Due to the proton’s depth-dose properties, this technique is more effective than photon treatment. Prior to proton therapy, pCT could help with the treatment planning. This technique simplifies proton treatment calculations since both processes involve the same particle interaction with matter. We simulated the experiment setup using G4beamline with the proton beam using a monolithic active pixel sensor (MAPS) as a proton tracker. The sensor’s output revealed that the ratio of data from protons interacting on the sensor was low, so we pre-processed the data with MATLAB by applying a mean filter to replace any empty pixels with the average of their nearby pixels. A 3D reconstruction was performed by stacking all the axial images reconstructed by the back projection method. The result shows that the material densities of reconstructed samples can be identified, however, it is still in the preliminary stage and not yet suitable for clinical trials. It is, however, possible to improve the quality of images and obtain a better 3D reconstruction for the pCT prototype by using a back-projection method.</jats:p

Silicon microchannel frames for high-energy physics experiments

The design of detectors used for experiments in high-energy physics requires a light, stiff, and efficient cooling system with a low material budget. The use of silicon microchannel cooling plates has gained considerable interest in the last decade. In this study, we propose the development of silicon microchannel cooling frames studied within the framework of the major upgrade of the Inner Tracking System (ITS) of the ALICE experiment at CERN. The preliminary results obtained with these frames demonstrate that they can withstand the internal pressure arising from the flow of the coolant with a limited mass penalt

Silicon microchannel frames for high-energy physics experiments

Abstract The design of detectors used for experiments in high-energy physics requires a light, stiff, and efficient cooling system with a low material budget. The use of silicon microchannel cooling plates has gained considerable interest in the last decade. In this study, we propose the development of silicon microchannel cooling frames studied within the framework of the major upgrade of the Inner Tracking System (ITS) of the ALICE experiment at CERN. The preliminary results obtained with these frames demonstrate that they can withstand the internal pressure arising from the flow of the coolant with a limited mass penalty.</jats:p

Room-temperature emission of muonium from aerogel and zeolite targets

Novel emitters of muonium (Mu = mu+ + e-) with high conversion efficiencies can enhance the precision of muonium spectroscopy experiments and enable next-generation searches for new physics. At the Paul Scherrer Institute (PSI), we investigate muonium production at room-temperature as well as in cryogenic environment using a superfluid helium converter. In this paper, we describe the development of compact detection schemes which resulted in the background-suppressed observation of atomic muonium in vacuum, and can be adapted for cryogenic measurements. Using these setups, we compared the emission characteristics of various muonium production targets at room temperature using low momentum (p mu = 11-13 MeV/c) muons, and observed muonium emission from zeolite targets into vacuum. For a specific laser-ablated aerogel target, we determined a muon-to-vacuum-muonium conversion efficiency of 7.23 +/- 0.05(stat)+1.06 -0.76(sys) %, assuming thermal emission of muonium. Moreover, we investigated muonium-helium collisions and from it we determined an upper temperature limit of 0.3 K for the superfluid helium converter

Measurement of the quadrupole moment of Re-185 and Re-187 from the hyperfine structure of muonic X rays

The hyperfine splitting of the 5g -> 4f transitions in muonic 185,187-Re has been measured using high resolution HPGe detectors and compared to state-of-the-art atomic theoretical predictions. The spectroscopic quadrupole moment has been extracted using modern fitting procedures and compared to the values available in literature obtained from muonic X rays of natural rhenium. The extracted values of the nuclear spectroscopic quadrupole moment are 2.07(5) barn and 1.94(5) barn, respectively for 185-Re and 187-Re. This work is part of a larger effort at the Paul Scherrer Institut towards the measurement of the nuclear charge radii of radioactive elements.Available on ArXiv: https://arxiv.org/abs/2003.02481status: publishe