The Central Drift Chamber for GlueX Jarvis, N.S.; Meyer, C.A.; Zihlmann, B. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2020, Letnik:
962, Številka:
C
Journal Article
Recenzirano
Odprti dostop
The Central Drift Chamber is a straw-tube wire chamber of cylindrical structure located surrounding the target inside the bore of the GlueX spectrometer solenoid. Its purpose is to detect and track ...charged particles with momenta as low as 0.25GeV/c and to identify low-momentum protons via energy loss. The construction of the detector is described and its operation and calibration are discussed in detail. The design goal of 150μm in position resolution has been reached.
The GlueX central drift chamber: Design and performance Van Haarlem, Y.; Meyer, C.A.; Barbosa, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2010, Letnik:
622, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Tests and studies concerning the design and performance of the GlueX Central Drift Chamber (CDC) are presented. A full-scale prototype was built to test and steer the mechanical and electronic ...design. Small scale prototypes were constructed to test for sagging and to do timing and resolution studies of the detector. These studies were used to choose the gas mixture and to program a Monte Carlo simulation that can predict the detector response in an external magnetic field. Particle identification and charge division possibilities were also investigated.
The Medipix-2 MXR is a single photon counting imaging detector developed at Cern. It provides 65,536 pixels in a 256 × 256 array, each equipped with low and high energy discriminators and a counter. ...The low (and high) threshold settings can be used to collect energy-resolved radiographic images. Applications include high-dynamic range, low-noise and material-resolved X-ray imaging. Each pixel has a different electronic gain and offset, so the energy calibration for each pixel needs to be determined separately. The Medipix detector provides only global low and high threshold settings, which are applied to all pixels. However, each pixel has additional 3-bit offset settings for the low and high thresholds. These settings can be used to fine-tune the thresholds for individual pixels and their calibration also needs to be determined. This paper describes a novel and fast method for calibrating the low energy discrimination threshold setting by using X-ray tube transmission spectra through different materials.
•65,536 pixels of the Medipix-2 imaging detector are simultaneously calibrated.•The calibration needs 4 measurements.•Only an X-ray tube and 2 filter materials are used.•This method is very simple and fast.•No complex Monte Carlo simulations are needed.
Abstract A method to fit Compton profiles in x‐ray fluorescence (XRF) spectroscopy using a line shape calculated from first principles is proposed. The fitting procedure incorporates the Compton ...profile calculations and the double Compton scattering line shape algorithm. The results demonstrate the effectiveness of the fitting approach in accurately describing the measured scattering spectra, with good agreement observed between the fit and experimental data. The findings of this study can be used for more accurate characterization of the scattering peaks in XRF spectroscopy.
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
+
.
The Central Drift Chamber for GlueX Jarvis, N. S.; Meyer, C. A.; Zihlmann, B. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2020, Letnik:
962, Številka:
C
Journal Article
Recenzirano
The Central Drift Chamber is a straw-tube wire chamber of cylindrical structure located surrounding the target inside the bore of the GlueX spectrometer solenoid. Its purpose is to detect and track ...charged particles with momenta as low as 0.25 GeV/c and to identify low-momentum protons via energy loss. The construction of the detector is described and its operation and calibration are discussed in detail. The design goal of 150 μm in position resolution has been reached.
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.
Exclusive electroproduction of
ω
mesons on unpolarized hydrogen and deuterium targets is studied in the kinematic region of
Q
2
>
1.0
GeV
2
, 3.0 GeV
<
W
<
6.3 GeV, and
-
t
′
<
0.2
GeV
2
. ...Results on the angular distribution of the
ω
meson, including its decay products, are presented. The data were accumulated with the HERMES forward spectrometer during the 1996–2007 running period using the 27.6 GeV longitudinally polarized electron or positron beam of HERA. The determination of the virtual-photon longitudinal-to-transverse cross-section ratio reveals that a considerable part of the cross section arises from transversely polarized photons. Spin density matrix elements are presented in projections of
Q
2
or
-
t
′
. Violation of
s
-channel helicity conservation is observed for some of these elements. A sizable contribution from unnatural-parity-exchange amplitudes is found and the phase shift between those amplitudes that describe transverse
ω
production by longitudinal and transverse virtual photons,
γ
L
∗
→
ω
T
and
γ
T
∗
→
ω
T
, is determined for the first time. A hierarchy of helicity amplitudes is established, which mainly means that the unnatural-parity-exchange amplitude describing the
γ
T
∗
→
ω
T
transition dominates over the two natural-parity-exchange amplitudes describing the
γ
L
∗
→
ω
L
and
γ
T
∗
→
ω
T
transitions, with the latter two being of similar magnitude. Good agreement is found between the HERMES proton data and results of a pQCD-inspired phenomenological model that includes pion-pole contributions, which are of unnatural parity.
A
bstract
The beam-helicity asymmetry in exclusive electroproduction of real photons by the longitudinally polarized Hera positron beam scattering off an unpolarized hydrogen target is measured at ...Hermes. The asymmetry arises from deeply virtual Compton scattering and its interference with the Bethe-Heitler process. Azimuthal amplitudes of the beam-helicity asymmetry are extracted from a data sample consisting of
ep
→
epγ
events with detection of all particles in the final state including the recoiling proton. The installation of a recoil detector, while reducing the acceptance of the experiment, allows the elimination of background from
ep
→
eN πγ
events, which was estimated to contribute an average of about 12% to the signal in previous Hermes publications. The removal of this background from the present data sample is shown to increase the magnitude of the leading asymmetry amplitude by 0
.
054 ± 0
.
016 to −0
.
328 ± 0
.
027 (stat
.
) ± 0
.
045 (syst
.
).
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