Operation of a negative ion gas time projection chamber without electronegative fill gases
Abstract
The high fidelity reconstruction of particle tracks in micropatterned gaseous time projection chambers renders this technology ideal for future rare-event searches, including direction-sensitive dark matter experiments. Large drift distances are typically required for such experiments, so that the overall spatial resolution is limited by diffusion. Negative ion drift exhibits lower diffusion than electron drift and is thus an attractive option for realising a large-scale detector. The use of electronegative gases to create negative ions introduces technical challenges, most notably a reduction in gain when compared to conventional gas mixtures. In this study, we demonstrate a new method for negative ion generation via dissociative electron attachment using the conventional molecular fill gas CF4. Our optical measurements of negative ion drift indicate electron attachment lengths of <1 mm and comparable gain to electron avalanches. The individual negative ion avalanches were also time-resolved, allowing the number of ions reaching the readout to be counted. We measure an improved energy resolution by single ion counting, relative to an integrated electron avalanche signal measured under identical gain conditions.
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BibTeX
@misc{mckie2026operation,
title = {{Operation of a negative ion gas time projection chamber without electronegative fill gases}},
author = {Lachlan J. McKie and Lindsey J. Bignell and Nicholas Adams and Victoria U. Bashu and Ferdos Dastgiri and Gregory J. Lane},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.09843},
eprint = {2609.09843},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.09843},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Operation of a negative ion gas time projection chamber without electronegative fill gases
AU - Lachlan J. McKie
AU - Lindsey J. Bignell
AU - Nicholas Adams
AU - Victoria U. Bashu
AU - Ferdos Dastgiri
AU - Gregory J. Lane
PY - 2026
DA - 2026/09/09
PB - arXiv
DO - 10.48550/arxiv.2609.09843
UR - https://arxiv.org/abs/2609.09843
AB - The high fidelity reconstruction of particle tracks in micropatterned gaseous time projection chambers renders this technology ideal for future rare-event searches, including direction-sensitive dark matter experiments. Large drift distances are typically required for such experiments, so that the overall spatial resolution is limited by diffusion. Negative ion drift exhibits lower diffusion than electron drift and is thus an attractive option for realising a large-scale detector. The use of electronegative gases to create negative ions introduces technical challenges, most notably a reduction in gain when compared to conventional gas mixtures. In this study, we demonstrate a new method for negative ion generation via dissociative electron attachment using the conventional molecular fill gas CF_4. Our optical measurements of negative ion drift indicate electron attachment lengths of <1 mm and comparable gain to electron avalanches. The individual negative ion avalanches were also time-resolved, allowing the number of ions reaching the readout to be counted. We measure an improved energy resolution by single ion counting, relative to an integrated electron avalanche signal measured under identical gain conditions.
ER -