Instruments

20 pages, 3862 KiB

Open AccessFeature PaperArticle

Investigating Slit-Collimator-Produced Carbon Ion Minibeams with High-Resolution CMOS Sensors

by Lennart Volz, Claire-Anne Reidel, Marco Durante, Yolanda Prezado, Christoph Schuy, Uli Weber and Christian Graeff

Instruments 2023, 7(2), 18; https://doi.org/10.3390/instruments7020018 - 06 Jun 2023

Cited by 1 | Viewed by 1447

Abstract

Particle minibeam therapy has demonstrated the potential for better healthy tissue sparing due to spatial fractionation of the delivered dose. Especially for heavy ions, the spatial fractionation could enhance the already favorable differential biological effectiveness at the target and the entrance region. Moreover, spatial fractionation could even be a viable option for bringing ions heavier than carbon back into patient application. To understand the effect of minibeam therapy, however, requires careful conduction of pre-clinical experiments, for which precise knowledge of the minibeam characteristics is crucial. This work introduces the use of high-spatial-resolution CMOS sensors to characterize collimator-produced carbon ion minibeams in terms of lateral fluence distribution, secondary fragments, track-averaged linear energy transfer distribution, and collimator alignment. Additional simulations were performed to further analyze the parameter space of the carbon ion minibeams in terms of beam characteristics, collimator positioning, and collimator manufacturing accuracy. Finally, a new concept for reducing the neutron dose to the patient by means of an additional neutron shield added to the collimator setup is proposed and validated in simulation. The carbon ion minibeam collimator characterized in this work is used in ongoing pre-clinical experiments on heavy ion minibeam therapy at the GSI. Full article

(This article belongs to the Special Issue Medical Applications of Particle Physics)

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14 pages, 2838 KiB

Open AccessArticle

Geant4 Simulation of Muon Absorption in Concrete Layers

by David Joffe and Christian Perez

Instruments 2023, 7(2), 17; https://doi.org/10.3390/instruments7020017 - 31 May 2023

Viewed by 1783

Abstract

Muography requires a detailed understanding of the absorption of muons in the material situated between the muon source and the detector. A large-statistics (>3 billion event) Geant4 simulation was run to simulate the absorption of muons in different thicknesses of concrete layers and to determine the effect of the material on the energies of muons that were not absorbed. The Geant4 simulation included a simple detector placed directly behind the absorbing material. A Geant4 simulation was also run for the same detector for alpha sources with no absorbing material and the results of this simulation were compared to the signals from the physical detector built in the laboratory and measured using standard alpha sources. The large-statistics simulations using muons of different energies were compared to the predictions of muon absorption from existing literature. The results of the simulations were in good agreement with both the measured signals from the laboratory as well as the predictions from the literature and the general method is found to be well-suited for studies used for muography involving material layers of uniform thickness. Full article

(This article belongs to the Special Issue Muography, Applications in Cosmic-Ray Muon Imaging)

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15 pages, 871 KiB

Open AccessArticle

Quenching Circuit Discriminator Architecture Impact on a Sub-10 ps FWHM Single-Photon Timing Resolution SPAD

by Frédéric Nolet, Valérie Gauthier, Samuel Parent, Frédéric Vachon, Nicolas Roy, Nicolas St-Jean, Serge A. Charlebois and Jean-François Pratte

Instruments 2023, 7(2), 16; https://doi.org/10.3390/instruments7020016 - 09 Apr 2023

Cited by 1 | Viewed by 1720

Abstract

In the field of radiation instrumentation, there is a desire to reach a sub-10 ps FWHM timing resolution for applications such as time-of-flight positron emission tomography, time-of-flight positron computed tomography and time-resolved calorimetry. One of the key parts of the detection chain for these applications is a single-photon detector and, in recent years, the first single-photon avalanche diode (SPAD) with a sub-10 ps timing resolution was presented. To reach such a timing resolution, the SPAD was read out by an operational amplifier operated in open-loop as a comparator. This paper presents a comparison between comparators and inverters to determine which type of leading-edge discriminator can obtain the best single-photon timing resolution. Six different quenching circuits (QCs) implemented in TSMC 65 nm are tested with SPADs of the same architecture and in the same operation conditions. This allows us to compare experimental results between the different QCs. This paper also presents a method to measure the SPAD signal slope, the SPAD excess voltage variation and simulations to determine the added jitter of different leading-edge discriminators. For some discriminator architectures, a cascode transistor was required to increase the maximum excess voltage of the QC. This paper also presents the impact on the single-photon timing resolution of adding a cascode transistor for a comparator or an inverter-based discriminator. This paper reports a 6.3 ps FWHM SPTR for a SPAD read out by a low-threshold comparator and a 6.8 ps FWHM SPTR for an optimized 1 V inverter using a cascode transistor for a higher excess voltage. Full article

(This article belongs to the Special Issue Feature Papers in Instruments 2021–2022)

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14 pages, 5415 KiB

Open AccessArticle

Design and Manufacture of a Test Device for Radiosynthesizer Vacuum Pumps

by Victor Amador Diaz, Scott E. Snyder and Amy L. Vavere

Instruments 2023, 7(2), 15; https://doi.org/10.3390/instruments7020015 - 06 Apr 2023

Viewed by 1804

Abstract

Vacuum pump wear is the most prevalent failure mode of the IBA Synthera^® automated radiochemistry system. Rebuilding or replacing the pump causes equipment downtime and increases the radiation exposure of the service personnel. We built a dedicated test device to assess new or rebuilt pumps prior to installation, thus reducing downtime and radiation exposure during repairs. The Testbed incorporates a microprocessor that actuates the pump, valves, and pressure sensor; communicates with the user through lights, buttons, and an alphanumeric screen; and outputs test results to a laptop. The Testbed increases productivity and safety in the radiochemistry laboratory. Full article

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6 pages, 9154 KiB

Open AccessProject Report

Fast Timing Detectors and Applications in Cosmic Ray Physics and Medical Science

by Christophe Royon, William d’Assignies D., Florian Gautier, Tommaso Isidori, Nicola Minafra and Alexander Novikov

Instruments 2023, 7(2), 14; https://doi.org/10.3390/instruments7020014 - 23 Mar 2023

Viewed by 1234

Abstract

We use fast silicon detectors and the fast sampling method originally developed for high energy physics for two applications: cosmic ray measurements in collaboration with NASA and dose measurements during flash beam cancer treatment. The cosmic ray measurement will benefit from the fast sampling method to measure the Bragg peak where the particle stops in the silicon detector and the dose measurement is performed by counting the number of particles that enter the detector. Full article

(This article belongs to the Special Issue Timing Detectors)

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Instruments, Volume 7, Issue 2 (June 2023) – 5 articles

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