30 kV coaxial vacuum-tight feedthrough for operation at cryogenic temperatures

In this paper we describe the technology of building a vacuum-tight high voltage feedthrough which is able to operate at voltages up to 30 kV. The feedthrough has a coaxial structure with a grounded sheath which makes it capable to lead high voltage potentials into cryogenic liquids, without risk of surface discharges in the gas phase above the liquid level. The feedthrough is designed to be used in ionization detectors, based on liquefied noble gases, such as Argon or Xenon

Ionization signals from electrons and alpha-particles in mixtures of liquid Argon and Nitrogen - perspectives on protons for Gamma Resonant Nuclear Absorption applications

In this paper we report on a detailed study of ionization signals produced by Compton electrons and alpha-particles in a Time Projection Chamber (TPC) flled with different mixtures of liquid Argon and Nitrogen. The measurements were carried out with Nitrogen concentrations up to 15% and a drift electric feld in the range 0-50 kV/cm. A prediction for proton ionization signals is made by means of interpolation. This study has been conducted in view of the possible use of liquid Ar-N2 TPCs for the detection of gamma-rays in the resonant band of the Nitrogen absorption spectrum, a promising technology for security and medical applications

A Global R&D Program on Liquid Ar Time Projection Chambers Under Execution at the University of Bern

AbstractA comprehensive R&D program on LAr Time Projection Chambers (LAr TPC) is presently being carried out at the University of Bern. Many aspects of this technology are under investigation: HV, purity, calibration, readout, etc. Furthermore, multi-photon interaction of UV-laser beams with LAr has successfully been measured. Possible applications of the LAr TPC technology in the field of homeland security are also being studied. In this paper, the main aspects of the program will be reviewed and the achievements underlined. Emphasis will be given to the largest device in Bern, i.e. the 5 m long ARGONTUBE TPC, meant to prove the feasibility of very long drifts in view of future large scale applications of the technique

Measurement of the two-photon absorption cross-section of liquid argon with a time projection chamber

This paper reports on laser-induced multiphoton ionization at 266 nm of liquid argon in a time projection chamber (LAr TPC) detector. The electron signal produced by the laser beam is a formidable tool for the calibration and monitoring of next-generation large-mass LAr TPCs. The detector that we designed and tested allowed us to measure the two-photon absorption cross-section of LAr with unprecedented accuracy and precision: sigma_ex=(1.24\pm 0.10stat \pm 0.30syst) 10^{-56} cm^4s{-1}.Comment: 15 pages, 9 figure

Measurement of B (Bs →dsX) with Bs semileptonic tagging

We report the first direct measurement of the inclusive branching fraction B(Bs→DsX) via Bs tagging in e+e-→ (5S) events. Tagging is accomplished through a partial reconstruction of semileptonic decays Bs→DsXℓν, where X denotes unreconstructed additional hadrons or photons and ℓ is an electron or muon. With 121.4 fb-1 of data collected at the (5S) resonance by the Belle detector at the KEKB asymmetric-energy e+e- collider, we obtain B(Bs→DsX)=(60.2±5.8±2.3)%, where the first uncertainty is statistical and the second is systematic

Evidence for a vector charmoniumlike state in e+e- → Ds+ Ds2∗ (2573)-+ c. c.

© 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article\u27s title, journal citation, and DOI. Funded by SCOAP3. We report the measurement of e+e-→Ds+Ds2∗(2573)-+c.c. via initial-state radiation using a data sample of an integrated luminosity of 921.9 fb-1 collected with the Belle detector at the γ(4S) and nearby. We find evidence for an enhancement with a 3.4σ significance in the invariant mass of Ds+Ds2∗(2573)-+c.c. The measured mass and width are (4619.8-8.0+8.9(stat.)±2.3(syst.)) MeV/c2 and (47.0-14.8+31.3(stat.)±4.6(syst.)) MeV, respectively. The mass, width, and quantum numbers of this enhancement are consistent with the charmoniumlike state at 4626 MeV/c2 recently reported by Belle in e+e-→Ds+Ds1(2536)-+c.c. The product of the e+e-→Ds+Ds2∗(2573)-+c.c. cross section and the branching fraction of Ds2∗(2573)-→D¯0K- is measured from Ds+Ds2∗(2573)- threshold to 5.6 GeV

Update of inclusive cross sections of single and pairs of identified light charged hadrons

© 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article\u27s title, journal citation, and DOI. Funded by SCOAP 3 We report new measurements of the production cross sections of pairs of charged pions and kaons as a function of their fractional energies using various fractional-energy definitions. Two different fractional-energy definitions were used and compared to the conventional fractional-energy definition reported previously. The new variables aim at either identifying dihadron cross sections in terms of single-hadron fragmentation functions, or to provide a means of characterizing the transverse momentum created in the fragmentation process. The results were obtained applying the updated initial-state radiation correction used in other recent Belle publications on light-hadron production cross sections. In addition, production cross sections of single charged pions, kaons, and protons were also updated using this initial-state radiation correction. The cross sections are obtained from a 558 fb-1 data sample collected at the γ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider

Study of B →p p ππ STUDY of B →p p ππ CHU K. et al.

© 2020 authors. Using a data sample of 772×106 BB pairs collected on the Ï\u27(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e-collider, we report the observation of B0→ppπ+π- A nd the first observation of B+→ppπ+π0. We measure a decay branching fraction of (0.83±0.17±0.17)×10-6 in B0→ppπ+π-for Mπ+π-\u3c1.22 GeV/c2 with a significance of 5.5 standard deviations. The contribution from B0→ppK0 is excluded. We measure a decay branching fraction of (4.58±1.17±0.67)×10-6 for B+→ppπ+π0 with Mπ+π0\u3c1.3 GeV/c2 with a significance of 5.4 standard deviations. We study the difference of the Mpp distributions in B0→ppπ+π- A nd B+→ppπ+π0

Search for B0 →x (3872)γ

© 2019 authors. Published by the American Physical Society. We report the results of a search for the decay B0→X(3872)(→J/ψπ+π-)γ. The analysis is performed on a data sample corresponding to an integrated luminosity of 711 fb-1 and containing 772×106BB pairs, collected with the Belle detector at the KEKB asymmetric-energy e+e- collider running at the (4S) resonance energy. We find no evidence for a signal and place an upper limit of B(B0→X(3872)γ)×B(X(3872)→J/ψπ+π-)\u3c5.1×10-7 at 90% confidence level

Observation of the Radiative Decays of ψ (1S) to χc1

© 2020 authors. Published by the American Physical Society. We report the first observation of the radiative decay of the ψ(1S) into a charmonium state. The significance of the observed signal of ψ(1S)→γχc1 is 6.3 standard deviations including systematics. The branching fraction is calculated to be B[ψ(1S)→γχc1]=[4.7-1.8+2.4(stat)-0.5+0.4(sys)×10-5]. We also searched for ψ(1S) radiative decays into χc0,2 and ηc(1S,2S), and set upper limits on their branching fractions. These results are obtained from a 24.9 fb-1 data sample collected with the Belle detector at the KEKB asymmetric-energy e+e- collider at a center-of-mass energy equal to the ψ(2S) mass using ψ(1S) tagging by the ψ(2S)→ψ(1S)π+π- transitions