Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 2303.07497

The Qweak High Performance LH2 Target

J. Brock·S. Covrig Dusa·J. Dunne·C. Keith·D. Meekins·J. Pierce·G. R. Smith·A. Subedi
View original source ↗Read source document ↗Export metadata ↓

Abstract

A high-power liquid hydrogen target was built for the Jefferson Lab Qweak experiment, which measured the tiny parity-violating asymmetry in $\vec{e}$p scattering at an incident energy of 1.16 GeV, and a Q$^2 = 0.025$ GeV$^{2}$. To achieve the luminosity of $1.7 \times 10^{39}$ cm$^{-2}$ s$^{-1}$, a 34.5 cm-long target was used with a beam current of 180 $\mu$A. The ionization energy-loss deposited by the beam in the target was 2.1 kW. The target temperature was controlled to within $\pm$0.02 K and the target noise (density fluctuations) near the experiment's beam helicity-reversal rate of 960 Hz was only 53 ppm. The 58 liquid liter target achieved a head of 11.4 m (7.6 kPa) and a mass flow of 1.2 $\pm$ 0.3 kg/s (corresponding to a volume flow of 17.4 $\pm$ 3.8 l/s) at the nominal 29 Hz rotation frequency of the recirculating centrifugal pump. We describe aspects of the design, operation, and performance of this target, the highest power LH2 target ever used in an electron scattering experiment to date.

Explore related subjects

physics.ins-detnucl-ex

Keep this discovery

BibTeXRIS

J. Brock, S. Covrig Dusa, J. Dunne, C. Keith, D. Meekins, J. Pierce, G. R. Smith, A. Subedi. 2023-03-13. The Qweak High Performance LH2 Target. https://doi.org/10.1016/j.nima.2023.168316

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

High-Speed Semi-FE Readout Module for ATLAS MDT at HL-LHC: Design and Production-Level Characterization

The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) introduces increased demands on the ATLAS Muon Spectrometer, particularly in terms of data throughput, timing distribution and system reliability. The Phase-II Chamber Service Module (CSM) is a key component of the upgraded Monitored Drift Tube (MDT) trigger and readout system, providing a high-speed interface between the front-end electronics and the backend systems. This paper describes the design and implementation of the Phase-II CSM, together with its validation. The results show that the CSM supports two independent optical uplinks, each operating at a line rate of 10.24 Gbps, together with clock distribution and slow control in the expected operating environment. Integration with small-diameter MDT (sMDT) chambers and tests with the prototype L0MDT trigger system are also presented. The CSM boards are now in production and will be used for installation and integration during the upcoming LHC Long Shutdown.

physics.ins-det↗
arXiv2026

Spectral Discrimination of Deposited Gamma-Ray Energies in a Simulated CeBr$_3$ Scintillator

We show that wavelength measurements of individual detected optical photons may provide additional information about gamma-ray energy deposited in a CeBr$_3$ crystal when the detected-photon-count distributions overlap for nearby gamma-ray energies. Monoenergetic 662 and 629 keV gammas are used in a Geant4 simulation of a $25\times25\times20~\mathrm{mm^3}$ CeBr$_3$ crystal. Assuming a light yield of $6.0\times10^4$ photons/MeV, a wavelength-independent photon-detection efficiency of 30%, and a wavelength resolution of $\sigma_{\lambda}=40$ nm, we find that the fraction of photons reconstructed above 385 nm gives an event-level separation of $\sim$ 2 standard deviations between the 662 and 629 keV event populations selected within the same $\sim$ 1%-wide detected-photon-count interval. No timing or reconstructed interaction-position information is used. The result demonstrates, within the present simulation model, that event-dependent optical spectra can retain energy information beyond an undifferentiated photon count.

physics.ins-det↗
arXiv2026

Operation of a negative ion gas time projection chamber without electronegative fill gases

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.

physics.ins-det↗