A
bstract
A comprehensive set of azimuthal single-spin and double-spin asymmetries in semi-inclusive leptoproduction of pions, charged kaons, protons, and antiprotons from transversely polarized ...protons is presented. These asymmetries include the previously published HERMES results on Collins and Sivers asymmetries, the analysis of which has been extended to include protons and antiprotons and also to an extraction in a three-dimensional kinematic binning and enlarged phase space. They are complemented by corresponding results for the remaining four single-spin and four double-spin asymmetries allowed in the one-photon-exchange approximation of the semi-inclusive deep-inelastic scattering process for target-polarization orientation perpendicular to the direction of the incoming lepton beam. Among those results, significant non-vanishing cos (
ϕ−ϕ
S
) modulations provide evidence for a sizable worm-gear (II) distribution,
g
1
T
q
x
p
T
2
. Most of the other modulations are found to be consistent with zero with the notable exception of large sin (
ϕ
S
) modulations for charged pions and
K
+
.
Azimuthal single-spin asymmetries of leptoproduced pions and charged kaons were measured on a transversely polarized hydrogen target. Evidence for a naive-T-odd, transverse-momentum-dependent parton ...distribution function is deduced from nonvanishing Sivers effects for pi(+), pi(0), and K(+/-), as well as in the difference of the pi(+) and pi(-) cross sections.
The Giessen Cosmic Station (GCS) has been designed and built at the Justus Liebig University Giessen. It offers unique possibilities to commission particle detectors, especially Cherenkov detectors, ...using high energetic cosmic muons. The GCS consists of four tracking boxes with 192 scintillator bars, two trigger plates and a lead absorber to filter out low energy muons. GCS provides particle tracking with the resolution of 4.6 mm in position and 3.8 mrad in angle over the active area of 50×50cm2 and with the muon rate of 0.2 particles/s including an energy cut of the trigger. By changing the geometry, the angular and position resolution can be further improved at the expense of the rate reduction. A trigger plate behind a lead absorber allows selection of high β>0.989 muons with kinetic energies above 600 MeV. The GCS has been designed to study the performance of the Endcap Disc DIRC (EDD) for the future PANDA experiment in Darmstadt which requires an excellent Particle Identification (PID) for pions and kaons up to 4.0 GeV/c momentum in EDD angular acceptance. Several measurements with cosmic muons and related Monte-Carlo simulations have been performed to validate the GCS design. The commissioning of the complete GCS setup was finished in 2019.
Latest Technological Advances with MCP-PMTs Lehmann, A; Belias, A; Dzhygadlo, R ...
Journal of physics. Conference series,
11/2022, Letnik:
2374, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This paper discusses the most recent advances with 2-inch MCP-PMTs. The status in terms of lifetime, detection efficiency, rate capability, time resolution, and gain behavior in magnetic fields are ...summarized. Significant progress in collection (CE) and quantum efficiency (QE) led to an excellent detection efficiency DQE = QE*CE of ∼30%. With a new DAQ setup up to several hundred anode pixels can be read out simultaneously in 3D allowing a glance “inside the PMT”. Parameters like dark count rates and ion afterpulsing are measurable as a function of the incident photon position as well as the temporal and spacial spread of recoil electrons and electronic and charge-sharing crosstalk even inside a magnetic field.
Excellent particle identification (PID) will be essential for the PANDA experiment at FAIR. The Barrel DIRC will separate kaons and pions with at least 3 s.d. for momenta up to 3.5 GeV/c and polar ...angles between 22 and 140 deg. After successful validation of the final design in the CERN PS/T9 beam line, the tendering process for the two most time- and cost-intensive items, radiator bars and MCP-PMTs, started in 2018. In Sep. 2019 Nikon was selected to build the fused silica bars and successfully completed the series production of 112 bars in Feb. 2021. Measurements of the mechanical quality of the bars were performed by Nikon and the optical quality was evaluated at GSI. In Dec. 2020, the contract for the fabrication of the MCP-PMTs was awarded to PHOTONIS and the delivery of the first-of-series MCP-PMTs is expected in July 2021. We present the design of the PANDA Barrel DIRC as well as the status of the component series production and the result of the quality assurance measurements.
A
bstract
Beam-helicity and beam-charge asymmetries in the hard exclusive leptoproduction of real photons from an unpolarised hydrogen target by a 27.6 GeV lepton beam are extracted from the H
ermes
...data set of 2006-2007 using a missing-mass event selection technique. The asymmetry amplitudes extracted from this data set are more precise than those extracted from the earlier data set of 1996-2005 previously analysed in the same manner by H
ermes
. The results from the two data sets are compatible with each other. Results from these combined data sets are extracted and constitute the most precise asymmetry amplitude measurements made in the H
ermes
kinematic region using a missing-mass event selection technique.
Mapping the density distribution and monitoring density changes under volcanoes and geological reservoirs is a major challenge in geology and volcanology. Muon radiography has a high potential to ...advance this field, but often there are no inexpensive high-end detectors available that are suitable for field installations. A DIRC-type Cherenkov detector as a muon camera has a small dimension and is suited for such field applications (MagmaDIRC idea). In measuring directions and energies of the incoming muons one can turn the mass density integrals along the lines of flight into a radiography image, and by discarting low-energy muons with their blurred angular information one obtains sharper images. In particular one may detect the time variation of the mass density distributions situated above the horizon line in a volcanic edifice that occurs when magma is filling its plumbing system or when the level of a lava lake changes. Using numerical simulations, we discuss design aspects and the requirements of such a DIRC system. Two sites are identified for proof-of-principle field measurements. The required measurement times are estimated for the given site conditions and morphology based on the specifications of an operational DIRC system. The merits of DIRC sensors are contrasted to other muon radiography techniques.
The ALFA Roman Pot detectors of ATLAS Khalek, S. Abdel; Allongue, B.; Anghinolfi, F. ...
Journal of instrumentation,
11/2016, Letnik:
11, Številka:
11
Journal Article
Recenzirano
Odprti dostop
The ATLAS Roman Pot system is designed to determine the total proton-proton cross section as well as the luminosity at the Large Hadron Collider (LHC) by measuring elastic proton scattering at very ...small angles. The system is made of four Roman Pot stations, located in the LHC tunnel in a distance of about 240 m at both sides of the ATLAS interaction point. Each station is equipped with tracking detectors, inserted in Roman Pots which approach the LHC beams vertically. The tracking detectors consist of multi-layer scintillating fibre structures read out by Multi-Anode-Photo-Multipliers.
Status of the PANDA Barrel DIRC Schwarz, C.; Ali, A.; Belias, A. ...
Journal of instrumentation,
03/2020, Letnik:
15, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The PANDA experiment will use cooled antiproton beams with high intensity stored in the High Energy Storage Ring at FAIR. Reactions on a fixed target producing charmed hadrons will shed light on the ...strong QCD. Three ring imaging Cherenkov counters are used for charged particle identification. The status of the Barrel DIRC (Detection of Internally Reflected Cherenkov light) is described. Its design is robust and its performance validated in experiments with test beams. The PANDA Barrel DIRC has entered the construction phase and will be installed in 2023/2024.
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