Speaker
Description
Micropatterned gas Time Projection Chambers (TPCs) are of interest for rare event physics where 3D reconstruction of low-energy recoil tracks has the potential to provide unique sensitivity to various searches, such as Dark Matter [1]. Camera based readouts for gas TPCs are gaining popularity to measure low-energy tracks for low cost per channel, high resolution and isolation of the readout from the sensitive gas volume.
We have recently developed a gas TPC called CYGNUS-n. This talk will discuss initial performance test of CYGNUS-n and the analysis methods. I will also report on measurements taken to explore the effect of the back flow of positive ions through the avalanche stage composed of two thin gas electron multipliers (GEMs), in low pressure CF4. Secondary avalanches caused by the back flowing positive ions on the first GEM stage were studied, along with the conditions which maximised these secondary avalanches. Upto 18% additional measurable light yield from secondary avalanches was observed. By fast gating the intensifier, we have confirmed the secondary avalanches are spatially correlated with the initial track, with additional expected broadening due to the inter-GEM diffusion. We have quantified spatial resolution of the initial, secondary and combined avalanches as measured by the camera. These results suggest principles for tuning the operational parameters of multi-GEM gain stages, and can be used to optimise the trade-off between measured light intensity and track broadening when using camera-based optical readouts for gas detectors.
[1] Vahsen, S.E., O’Hare, C.A.J., Lynch, W.A., Spooner, N.J.C., Baracchini, E., Barbeau, P., Battat, J.B.R., Crow, B., Deaconu, C., Eldridge, C. and Ezeribe, A.C., 2020. CYGNUS: Feasibility of a nuclear recoil observatory with directional sensitivity to dark matter and neutrinos. arXiv preprint arXiv:2008.12587.
| I am the presenting author | Yes |
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