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Abstract We present a new investigation of the intergalactic medium near reionization using dark gaps in the Lyβforest. With its lower optical depth, Lyβoffers a potentially more sensitive probe to any remaining neutral gas compared to the commonly used Lyαline. We identify dark gaps in the Lyβforest using spectra of 42 QSOs atzem> 5.5, including new data from the XQR-30 VLT Large Programme. Approximately 40% of these QSO spectra exhibit dark gaps longer than 10h−1Mpc atz≃ 5.8. By comparing the results to predictions from simulations, we find that the data are broadly consistent both with models where fluctuations in the Lyαforest are caused solely by ionizing ultraviolet background fluctuations and with models that include large neutral hydrogen patches atz< 6 due to a late end to reionization. Of particular interest is a very long (L= 28h−1Mpc) and dark (τeff≳ 6) gap persisting down toz≃ 5.5 in the Lyβforest of thez= 5.85 QSO PSO J025−11. This gap may support late reionization models with a volume-weighted average neutral hydrogen fraction of 〈xH I〉 ≳ 5% byz= 5.6. Finally, we infer constraints on 〈xH I〉 over 5.5 ≲z≲ 6.0 based on the observed Lyβdark gap length distribution and a conservative relationship between gap length and neutral fraction derived from simulations. We find 〈xH I〉 ≤ 0.05, 0.17, and 0.29 atz≃ 5.55, 5.75, and 5.95, respectively. These constraints are consistent with models where reionization ends significantly later thanz= 6.
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This content will become publicly available on March 1, 2026
Calibration of Solid State Nuclear Track Detectors for rare event searches
Abstract The calibration of the CR39®and Makrofol®Nuclear Track Detectors of the MoEDAL experiment at the CERN-LHC was performed by exposing stacks of detector foils to heavy ion beams with energies ranging from 340 MeV/nucleon to 150 GeV/nucleon. After chemical etching, the base areas and lengths of etch-pit cones were measured using automatic and manual optical microscopes. The response of the detectors as measured by the ratio of the track-etching rate over the bulk-etching rate, was determined over a range extending from their threshold at Z/β∼ 7 and ∼ 50 for CR39 and Makrofol, respectively, up to Z/β∼ 92.
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- Award ID(s):
- 2309505
- PAR ID:
- 10580216
- Publisher / Repository:
- JINST
- Date Published:
- Journal Name:
- Journal of Instrumentation
- Volume:
- 20
- Issue:
- 03
- ISSN:
- 1748-0221
- Page Range / eLocation ID:
- P03014
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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