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Instruments, Volume 8, Issue 2 (June 2024) – 8 articles

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16 pages, 7436 KiB  
Article
Microparticle Hybrid Target Simulation for keV X-ray Sources
by Rolf Behling, Christopher Hulme, Panagiotis Tolias, Gavin Poludniowski and Mats Danielsson
Instruments 2024, 8(2), 32; https://doi.org/10.3390/instruments8020032 - 22 May 2024
Viewed by 327
Abstract
The spatiotemporal resolution of diagnostic X-ray images obtained with rotating-anode X-ray tubes has remained limited as the development of rigid, high-performance target materials has slowed down. However, novel imaging techniques using finer detector pixels and orthovolt cancer therapy employing narrow X-ray focal spots [...] Read more.
The spatiotemporal resolution of diagnostic X-ray images obtained with rotating-anode X-ray tubes has remained limited as the development of rigid, high-performance target materials has slowed down. However, novel imaging techniques using finer detector pixels and orthovolt cancer therapy employing narrow X-ray focal spots demand improved output from brilliant keV X-ray sources. Since its advent in 1929, rotating-anode technology has become the greatest bottleneck to improvement. To overcome this limitation, the current authors have devised a novel X-ray generation technology based on tungsten microparticle targets. The current study investigated a hybrid solution of a stream of fast tungsten microparticles and a rotating anode to both harvest the benefits of the improved performance of the new solution and to reuse known technology. The rotating anode captures energy that may pass a partially opaque microparticle stream and thereby contributes to X-ray generation. With reference to fast-rotating anodes and a highly appreciated small focal spot of a standardized size of 0.3 for an 8° target angle (physical: 0.45 mm × 4.67 mm), we calculated a potential output gain of at least 85% for non-melting microparticles and of 124% if melting is envisioned. Microparticle charging can be remediated by electron backscattering and electron field emission. The adoption of such a solution enables substantially improved image resolution. Full article
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10 pages, 1543 KiB  
Article
Design and Performance of a Low-Energy Gamma-Ray Trigger System for HERD
by Luis Fariña, Keerthana Lathika, Giulio Lucchetta, Monong Yu, Joan Boix, Laia Cardiel-Sas, Oscar Blanch, Manel Martinez and Javier Rico
Instruments 2024, 8(2), 31; https://doi.org/10.3390/instruments8020031 - 4 May 2024
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Abstract
The High Energy cosmic-Radiation Detection (HERD) facility has been proposed as one of the main experiments on board the Chinese space station. HERD is scheduled to be installed around 2027 and to operate for at least 10 years. Its main scientific goals are [...] Read more.
The High Energy cosmic-Radiation Detection (HERD) facility has been proposed as one of the main experiments on board the Chinese space station. HERD is scheduled to be installed around 2027 and to operate for at least 10 years. Its main scientific goals are the study of the cosmic ray spectrum and composition up to the PeV energy range, indirect dark matter detection, and all-sky gamma-ray observation above 100 MeV. HERD features a novel design in order to optimize its acceptance per weight, with a central 3D imaging calorimeter surrounded on top and on its four lateral sides by complementary subdetectors. A dedicated trigger, dubbed the ultra-low-energy gamma-ray (ULEG) trigger, is required to enable the detection of gamma rays down to ~100 MeV. The ULEG trigger design is based upon the search for energy deposition patterns on the tracker and the anticoincidence shield, compatible with the conversion of a gamma ray within the tracker volume and resulting in enough tracker hits to allow for a good-quality gamma-ray direction reconstruction. We describe the current status of the design of the ULEG trigger system. We also characterize its performance in detecting gamma rays as inferred from Monte Carlo studies. Full article
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15 pages, 757 KiB  
Article
A Concept for a Multipurpose Time-of-Flight Neutron Reflectometer at Compact Neutron Sources
by Raul-Victor Erhan, Victor-Otto de Haan, Christoph Frommen, Kenneth Dahl Knudsen, Isabel Llamas-Jansa and Bjørn Christian Hauback
Instruments 2024, 8(2), 30; https://doi.org/10.3390/instruments8020030 - 24 Apr 2024
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Abstract
The design of a time-of-flight neutron reflectometer proposed for the new generation of compact neutron sources is presented. The reflectometer offers the possibility to use spin-polarized neutrons. The reflectometer design presented here takes advantage of a cold neutron source and uses neutrons with [...] Read more.
The design of a time-of-flight neutron reflectometer proposed for the new generation of compact neutron sources is presented. The reflectometer offers the possibility to use spin-polarized neutrons. The reflectometer design presented here takes advantage of a cold neutron source and uses neutrons with wavelengths in the range of 2–15 Å for the unpolarized mode. In general, due to tight spatial restrictions and the need to avoid moving parts inside the beam channel, a multi-channel collimator guide and reflective neutron guide are used for the first section of the instrument. This enables definition of the desired wavelength band and easy selection of one out of three different Q-resolutions. A low background for the collimator system and the reflectometer is ensured by employing a tangential beam channel and an in-channel sapphire filter. The second section is the time-of-flight (TOF) system, which uses a double-disk neutron chopper followed by polarization elements, the sample environment and the neutron detector system. Monte Carlo simulations and neutron beamline intensity measurements are presented. The design considerations are adoptable for neutron sources where space is limited and sections of the instrument are in a high-radiation environment. Full article
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12 pages, 2961 KiB  
Article
Digital Miniature Cathode Ray Magnetometer
by Marcos Turqueti, Gustav Wagner, Azriel Goldschmidt and Rebecca Carney
Instruments 2024, 8(2), 29; https://doi.org/10.3390/instruments8020029 - 24 Apr 2024
Viewed by 509
Abstract
In this study, we introduce the concept and construction of an innovative Digital Miniature Cathode Ray Magnetometer designed for the precise detection of magnetic fields. This device addresses several limitations inherent to magnetic probes such as D.C. offset, nonlinearity, temperature drift, sensor aging, [...] Read more.
In this study, we introduce the concept and construction of an innovative Digital Miniature Cathode Ray Magnetometer designed for the precise detection of magnetic fields. This device addresses several limitations inherent to magnetic probes such as D.C. offset, nonlinearity, temperature drift, sensor aging, and the need for frequent recalibration, while capable of operating in a wide range of magnetic fields. The core principle of this device involves the utilization of a charged particle beam as the sensitivity medium. The system leverages the interaction of an electron beam with a scintillator material, which then emits visible light that is captured by an imager. The emitted scintillation light is captured by a CMOS sensor. This sensor not only records the scintillation light but also accurately determines the position of the electron beam, providing invaluable spatial information crucial for magnetic field mapping. The key innovation lies in the combination of electron beam projection, CMOS imager scintillation-based detection, and digital image signal processing. By employing this synergy, the magnetometer achieves remarkable accuracy, sensitivity and dynamic range. The precise position registration enabled by the CMOS sensor further enhances the device’s utility in capturing complex magnetic field patterns, allowing for 2D field mapping. In this work, the optimization of the probe’s performance is tailored for applications related to the characterization of insertion devices in light sources, including undulators. Full article
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11 pages, 5709 KiB  
Article
Drive Bunch Train for the Dielectric Trojan Horse Experiment at the Argonne Wakefield Accelerator
by Gerard Andonian, Nathan Burger, Nathan Cook, Scott Doran, Tara Hodgetts, Seongyeol Kim, Gwanghui Ha, Wanming Liu, Walter Lynn, Nathan Majernik, John Power, Alexey Pronikov, James Rosenzweig and Eric Wisniewski
Instruments 2024, 8(2), 28; https://doi.org/10.3390/instruments8020028 - 10 Apr 2024
Viewed by 688
Abstract
The recently demonstrated concept of the plasma photocathode, whereby a high-brightness bunch is initialized by laser ionization within a plasma wakefield acceleration bubble, is informally referred to as Trojan Horse wakefield acceleration. In a similar vein, the dielectric Trojan Horse concept incorporates a [...] Read more.
The recently demonstrated concept of the plasma photocathode, whereby a high-brightness bunch is initialized by laser ionization within a plasma wakefield acceleration bubble, is informally referred to as Trojan Horse wakefield acceleration. In a similar vein, the dielectric Trojan Horse concept incorporates a dielectric-lined waveguide to support a charged particle beam-driven accelerating mode and uses laser initiated ionization of neutral gas within the waveguide to generate a witness beam. One of the advantages of the dielectric Trojan Horse concept is the reduced requirements in terms of timing precision due to operation at a lower frequency. In this paper, we present experimental results on the generation and characterization of a four-bunch drive train for resonant excitation of wakefields in a cylindrical dielectric waveguide conducted at the Argonne Wakefield Accelerator facility. The results lay the foundation for the demonstration of a plasma photocathode scheme within a dielectric wakefield accelerating structure. Modifications to improve capture efficiency with improved beam transmission are suggested as well. Full article
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14 pages, 2348 KiB  
Article
Jitter Measurements of 1 cm2 LGADs for Space Experiments
by Ashish Bisht, Leo Cavazzini, Matteo Centis Vignali, Fabiola Caso, Omar Hammad Ali, Francesco Ficorella, Maurizio Boscardin and Giovanni Paternoster
Instruments 2024, 8(2), 27; https://doi.org/10.3390/instruments8020027 - 29 Mar 2024
Viewed by 806
Abstract
This work explores the possibility of using Low Gain Avalanche Diodes (LGADs) for tracker-based experiments studying Charged Cosmic Rays (CCRs) in space. While conventional silicon microstrip sensors provide only spatial information about the charged particle passing through the tracker, LGADs have the potential [...] Read more.
This work explores the possibility of using Low Gain Avalanche Diodes (LGADs) for tracker-based experiments studying Charged Cosmic Rays (CCRs) in space. While conventional silicon microstrip sensors provide only spatial information about the charged particle passing through the tracker, LGADs have the potential to provide additional timing information with a resolution in the order of tens of picoseconds. For the first time, it has been demonstrated that an LGAD with an active area of approximately 1 cm2 can achieve a jitter of less than 40 ps. A comparison of design and gain layers is carried out to understand which provides the best time resolution. For this purpose, laboratory measurements of sensors’ electrical properties and gain using LED and an Infrared laser, as well as their jitter, were performed. Full article
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12 pages, 5615 KiB  
Article
Development of High-Voltage Electrodes for Neutron Scattering Sample Environment Devices
by Guoliang Sun, Tingting Guo, Bao Yuan, Xiaojing Yang and Guang Wang
Instruments 2024, 8(2), 26; https://doi.org/10.3390/instruments8020026 - 28 Mar 2024
Viewed by 689
Abstract
The sample environment is essential to neutron scattering experiments as it induces the sample under study into a phase or state of particular interest. Various sample environments have been developed, yet the high-voltage electric field has rarely been documented. In this study, Bruce [...] Read more.
The sample environment is essential to neutron scattering experiments as it induces the sample under study into a phase or state of particular interest. Various sample environments have been developed, yet the high-voltage electric field has rarely been documented. In this study, Bruce electrodes with various sectional geometries and chamber sizes were examined by using simulation modeling based on ANSYS Maxwell. A large uniform field region where samples would sit could be achieved in the planar region for all specifications, but the size of the region and the field strength varied with the gap distance between electrodes. The edging effect was inherently observed even for bare electrodes, about 1.7% higher in the sinusoidal region than the planar region, and was significantly deteriorated when a chamber was applied. This effect, however, presented an exponential decrease as the minimum distance between the electrode edge and the chamber shell increased. A compromise between the spatial confinement and the achievable field (strength and uniform region) could be reached according to the unique applicability of neutron instruments. This research provides a theoretical basis for the subsequent design and manufacturing of high-voltage sample environment devices. Full article
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17 pages, 13163 KiB  
Article
The Imaging X-ray Polarimetry Explorer (IXPE) and New Directions for the Future
by Paolo Soffitta
Instruments 2024, 8(2), 25; https://doi.org/10.3390/instruments8020025 - 25 Mar 2024
Viewed by 792
Abstract
An observatory dedicated to X-ray polarimetry has been operational since 9 December 2021. The Imaging X-ray Polarimetry Explorer (IXPE), a collaboration between NASA and ASI, features three X-ray telescopes equipped with detectors sensitive to linear polarization set to 120°. This marks the first [...] Read more.
An observatory dedicated to X-ray polarimetry has been operational since 9 December 2021. The Imaging X-ray Polarimetry Explorer (IXPE), a collaboration between NASA and ASI, features three X-ray telescopes equipped with detectors sensitive to linear polarization set to 120°. This marks the first instance of a three-telescope SMEX mission. Upon reaching orbit, an extending boom was deployed, extending the optics and detector to a focal length of 4 m. IXPE targets each celestial source through dithering observations. This method is essential for supporting on-ground calibrations by averaging the detector’s response across a section of its sensitive plane. The spacecraft supplies power, enables attitude determination for subsequent on-ground attitude reconstruction, and issues control commands. After two years of observation, IXPE has detected significant linear polarization from nearly all classes of celestial sources emitting X-rays. This paper outlines the IXPE mission’s achievements after two years of operation in orbit. In addition, we report developments for future high-throughput X-ray optics that will have much smaller dead-times by using a new generation of Applied Specific Integrated Circuits (ASIC), and may provide 3D reconstruction of photo-electron tracks. Full article
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