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Title: Optical transmission characterization of fused silica materials irradiated at the CERN Large Hadron Collider
The Target Absorbers for Neutrals (TANs) represent one of the most radioactive regions in the Large Hadron Collider. Seven 40cm long fused silica rods with different dopant specifications, manufactured by Heraeus, were irradiated in one of the TANs located around the ATLAS experiment by the Beam RAte of Neutrals (BRAN) detector group. This campaign took place during Run 2 data taking, which occurred between 2016 and 2018. This paper reports a complete characterization of optical transmission per unit length of irradiated fused silica materials as a function of wavelength (240 nm–1500 nm), dose (up to 18 MGy), and level of OH and H2 dopants introduced in the manufacturing process. The dose delivered to the rods was estimated using Monte Carlo simulations performed by the CERN FLUKA team. more »« less
The High Luminosity LHC (HL-LHC) provides the opportunity to study heavy ion, proton-nucleus, photon-nucleus and photon-photon collisions with unprecedented luminosities at the TeV scale. The LHC heavy ion community has mapped out an extensive range of physics measurements at the HLLHC that will push forward our understanding of both QCD, QED and even electroweak physics. The measurement of forward neutrons and photons in Zero Degree Calorimeters (ZDCs) is essential for event classification and triggering. In order to reach the required luminosities, the LHC interaction regions will be redesigned, necessitating the need to build new ZDCs that will be both narrower and much more radiation tolerant. This challenge motivated the formation of a joint project between ATLAS and CMS to build new ZDCs for Run 4, JZCaP. The ZDCs are based on radiation-hard fused silica rods that produce Cherenkov light. These rods have been developed by Heraeus Quartzglas in collaboration with JZCaP and the LHC BRAN and FLUKA groups. The Run 4 ZDCs (HL-ZDCs) are the first joint detector project between CMS and ATLAS. This talk will present the capabilities of the new ZDCs and recent R&D highlights.
Cadmium telluride (CdTe) solar cells are a promising photovoltaic (PV) technology for producing power in space owing to their high-efficiency (> 22.1 %), potential for specific power, and cost-effective manufacturing processes. In contrast to traditional space PVs, the high-Z (atomic number) CdTe absorbers can be intrinsically robust under extreme space radiation, offering long-term stability. Despite these advantages, the performance assessment of CdTe solar cells under high-energy particle irradiation (e.g., photons, neutrons, charged particles) is limited in the literature, and their stability is not comprehensively studied. In this work, we present the PV response of n-CdS / p-CdTe PVs under accelerated neutron irradiation. We measure PV properties of the devices at different neutron/photon doses. The equivalent dose deposited in the CdTe samples is simulated with deterministic and Monte Carlo radiation transport methods.
Thin-film CdTe solar cells were synthesized on a fluorine-doped tin oxide (FTO) coated glass substrate (≈ 4 cm × 4 cm). CdS:O (≈ 100 nm) was reactively RF sputtered in an oxygen/argon ambient followed by a close-spaced sublimation deposition of CdTe (≈ 3.5 μm) in an oxygen/helium ambient. The sample was exposed to a 10 min vapor CdCl2 in oxygen/helium ambient at 430˚C. The samples were exposed to a wet CuCl2 solution prior to anneal 200ºC. A gold back-contact was formed on CdTe via thermal evaporation. The final sample contains 16 CdTe devices. For neutron irradiation, we cleaved the CdTe substrate into four samples and exposed two samples to ≈ 90 kW reactor power neutron radiation for 5.5 hours and 8.2 hours, respectively, in our TRIGA (Training, Research, Isotopes, General Atomics) reactor.
We observed a noticeable color change of the glass substrates to brown after the neutron/gamma reactor exposure. Presumably, the injected high-energy neutrons caused the breaking of chemical bonds and the displacement of atoms in the glass substrates, creating point defects and color centers. The I-V characteristics showed noticeable deterioration with over 8 hour radiations. Specifically, the saturation current of the control devices was ≈ 25 nA increasing to 1 μA and 10 μA for the 5.5-hour and 8.2-hour radiated samples, respectively. The turn-on voltage of the control devices (≈ 0.85 V) decreased with the irradiated sample (≈ 0.75 V for 5.5-hour and ≈ 0.5 V for 8.2-hour exposures), implying noticeable radiation damage occurred at the heterojunction. The higher values of the ideality factor for irradiated devices (n > 2.2) compared to that of the control devices (n ≈ 1.3) also support the deterioration of the p-n junction. We observed the notable decrease in shunt resistance (RSH) and the increase in series resistance (Rs) with the neutron dose. It is possible that Cu ions introduced during the CuCl2 treatment may migrate into CdTe grain boundaries (GBs). The presence of Cu ions at GBs can create additional leakage paths for photocarrier transport, deteriorating the overall PV performance.
We estimated the radiation dose of CdTe in comparison to Si (conventional PV) using a UUTR model (e.g., MCNP6 2D UTR Reactor simulations). In this model, we simulated Si and CdTe at the center point of the triangular fuel lattice and used an “unperturbed flux” tally in the water. Our simulations yielded a dose rate of 6916 Gy/s of neutrons and 16 Gy/s of photons for CdTe, and 1 Gy/s of neutrons and 21 Gy/s of photons for Si (doses +/- <1%). The large dose rate of neutrons in CdTe is mainly attributed to the large thermal neutron absorption cross-section of 113Cd. Based on this estimation, we calculate that the exposure of our CdTe PVs is equivalent to several million years in LEO (Low-Earth Orbit), or about 10,000 years for Si in LEO. Currently, we are working on a low-dose neutron/photon radiation on CdTe PVs and their light I-Vs and microstructural characterizations to gain better understanding on the degradation of CdTe PVs.
Manipulation and structural modifications of 2D materials for nanoelectronic and nanofluidic applications remain obstacles to their industrial‐scale implementation. Here, it is demonstrated that a 30 kV focused ion beam can be utilized to engineer defects and tailor the atomic, optoelectronic, and structural properties of monolayer transition metal dichalcogenides (TMDs). Aberration‐corrected scanning transmission electron microscopy is used to reveal the presence of defects with sizes from the single atom to 50 nm in molybdenum (MoS2) and tungsten disulfide (WS2) caused by irradiation doses from 1013to 1016ions cm−2. Irradiated regions across millimeter‐length scales of multiple devices are sampled and analyzed at the atomic scale in order to obtain a quantitative picture of defect sizes and densities. Precise dose value calculations are also presented, which accurately capture the spatial distribution of defects in irradiated 2D materials. Changes in phononic and optoelectronic material properties are probed via Raman and photoluminescence spectroscopy. The dependence of defect properties on sample parameters such as underlying substrate and TMD material is also investigated. The results shown here lend the way to the fabrication and processing of TMD nanodevices.
Look, David C.; Leedy, Kevin D.; Santia, Marco D.; Badescu, Stefan C.(
, Communications Materials)
null
(Ed.)
Abstract Disorder arising from random locations of charged donors and acceptors introduces localization and diffusive motion that can lead to constructive electron interference and positive magnetoconductivity. At very low temperatures, 3D theory predicts that the magnetoconductivity is independent of temperature or material properties, as verified for many combinations of thin-films and substrates. Here, we find that this prediction is apparently violated if the film thickness d is less than about 300 nm. To investigate the origin of this apparent violation, the magnetoconductivity was measured at temperatures T = 15 – 150 K in ten, Sn-doped In 2 O 3 films with d = 13 – 292 nm, grown by pulsed laser deposition on fused silica. We observe a very strong thickness dependence which we explain by introducing a theory that postulates a second source of disorder, namely, non-uniform interface-induced defects whose number decreases exponentially with the interface distance. This theory obeys the 3D limit for the thickest samples and yields a natural figure of merit for interface disorder. It can be applied to any degenerate semiconductor film on any semi-insulating substrate.
Rasel, Md Abu Jafar; Stepanoff, Sergei; Haque, Aman; Wolfe, Douglas E.; Ren, Fan; Pearton, Stephen J.(
, Journal of Vacuum Science & Technology B)
Radiation damage in electronic devices is known to be influenced by physics, design, and materials system. Here, we report the effects of biasing state (such as ON and OFF) and pre-existing damage in GaN high electron mobility transistors exposed to γ radiation. Controlled and accelerated DC biasing was used to prestress the devices, which showed significant degradation in device characteristics compared to pristine devices under ON and OFF states after γ irradiation. The experiment is performed in situ for the ON-state to investigate transient effects during irradiation until the total dose reaches 10 Mrad. It shows that threshold voltage, maximum transconductance, and leakage current initially decrease with dosage but slowly converge to a steady value at higher doses. After 10 Mrad irradiation, the OFF-state device demonstrates larger RON and one order of magnitude increased leakage current compared to the ON-state irradiated device. The micro-Raman study also confirms that the ON-state operation shows more radiation hardness than OFF and prestressed devices. Prestressed devices generate the highest threshold voltage shift from −2.85 to −2.49 V and two orders of magnitude higher leakage current with decreased saturation current after irradiation. These findings indicate that high electric fields during stressing can generate defects by modifying strain distribution, and higher defect density can not only create more charges during irradiation but also accelerate the diffusion process from the ionizing track to the nearest collector and consequently degrade device performances.
Yang, S., Tate, A., Longo, R., Sabate Gilarte, M., Cerutti, F., Mazzoni, S., Grosse Perdekamp, M., Bravin, E., Citron, Z., Kühn, B., Nürnberg, F., Cole, B., Fritchie, J., I.Gelber, Hoppesch, M., Jackobsen, S., Koeth, T., Lantz, C., MacLean, D., Mignerey, A., Murray, M., Palm, M., Phipps, M., Popescu, S., Santiago, N., Shenkar, S., and Steinberg, P. Optical transmission characterization of fused silica materials irradiated at the CERN Large Hadron Collider. Retrieved from https://par.nsf.gov/biblio/10472693. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 1055.C Web. doi:10.1016/j.nima.2023.168523.
Yang, S., Tate, A., Longo, R., Sabate Gilarte, M., Cerutti, F., Mazzoni, S., Grosse Perdekamp, M., Bravin, E., Citron, Z., Kühn, B., Nürnberg, F., Cole, B., Fritchie, J., I.Gelber, Hoppesch, M., Jackobsen, S., Koeth, T., Lantz, C., MacLean, D., Mignerey, A., Murray, M., Palm, M., Phipps, M., Popescu, S., Santiago, N., Shenkar, S., & Steinberg, P. Optical transmission characterization of fused silica materials irradiated at the CERN Large Hadron Collider. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1055 (C). Retrieved from https://par.nsf.gov/biblio/10472693. https://doi.org/10.1016/j.nima.2023.168523
Yang, S., Tate, A., Longo, R., Sabate Gilarte, M., Cerutti, F., Mazzoni, S., Grosse Perdekamp, M., Bravin, E., Citron, Z., Kühn, B., Nürnberg, F., Cole, B., Fritchie, J., I.Gelber, Hoppesch, M., Jackobsen, S., Koeth, T., Lantz, C., MacLean, D., Mignerey, A., Murray, M., Palm, M., Phipps, M., Popescu, S., Santiago, N., Shenkar, S., and Steinberg, P.
"Optical transmission characterization of fused silica materials irradiated at the CERN Large Hadron Collider". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 1055 (C). Country unknown/Code not available: Nucl.Instrum.Meth.A 1055 (2023) 168523. https://doi.org/10.1016/j.nima.2023.168523.https://par.nsf.gov/biblio/10472693.
@article{osti_10472693,
place = {Country unknown/Code not available},
title = {Optical transmission characterization of fused silica materials irradiated at the CERN Large Hadron Collider},
url = {https://par.nsf.gov/biblio/10472693},
DOI = {10.1016/j.nima.2023.168523},
abstractNote = {The Target Absorbers for Neutrals (TANs) represent one of the most radioactive regions in the Large Hadron Collider. Seven 40cm long fused silica rods with different dopant specifications, manufactured by Heraeus, were irradiated in one of the TANs located around the ATLAS experiment by the Beam RAte of Neutrals (BRAN) detector group. This campaign took place during Run 2 data taking, which occurred between 2016 and 2018. This paper reports a complete characterization of optical transmission per unit length of irradiated fused silica materials as a function of wavelength (240 nm–1500 nm), dose (up to 18 MGy), and level of OH and H2 dopants introduced in the manufacturing process. The dose delivered to the rods was estimated using Monte Carlo simulations performed by the CERN FLUKA team.},
journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
volume = {1055},
number = {C},
publisher = {Nucl.Instrum.Meth.A 1055 (2023) 168523},
author = {Yang, S. and Tate, A. and Longo, R. and Sabate Gilarte, M. and Cerutti, F. and Mazzoni, S. and Grosse Perdekamp, M. and Bravin, E. and Citron, Z. and Kühn, B. and Nürnberg, F. and Cole, B. and Fritchie, J. and I.Gelber and Hoppesch, M. and Jackobsen, S. and Koeth, T. and Lantz, C. and MacLean, D. and Mignerey, A. and Murray, M. and Palm, M. and Phipps, M. and Popescu, S. and Santiago, N. and Shenkar, S. and Steinberg, P.},
}
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