Measurements of the kinematic distributions of
J
/
ψ
mesons produced in
p
–C,
p
–Ti and
p
–W collisions at
in the Feynman-
x
region −0.34<
x
F
<0.14 and for transverse momentum up to
p
T
=5.4 GeV/c ...are presented. The
x
F
and
p
T
dependencies of the nuclear suppression parameter,
α
, are also given. The results are based on 2.4×10
5
J
/
ψ
mesons reconstructed in both the
e
+
e
−
and
μ
+
μ
−
decay channels. The data have been collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The measurement explores the negative region of
x
F
for the first time. The average value of
α
in the measured
x
F
region is 0.981±0.015. The data suggest that the strong nuclear suppression of
J
/
ψ
production previously observed at high
x
F
turns into an enhancement at negative
x
F
.
Processing of the data of ring transition radiation detectors Aginian, M.A.; Ispirian, K.A.; Ispiryan, M.K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2004, Letnik:
522, Številka:
1
Journal Article
Recenzirano
In the recently proposed ring transition radiation detectors (RTRD) it is possible to detect the total number, position and energy of X-ray transition radiation photons produced in a stack of plates ...by single relativistic heavy ion (RHI). Some possible methods of processing of RTRD data are considered that provide high resolution for the measurement of the RHI Lorentz factor.
Ultrafast CO2 laser technology: Application in ion acceleration Pogorelsky, I.V.; Yakimenko, V.; Polyanskiy, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2010, Letnik:
620, Številka:
1
Journal Article
Recenzirano
We review principles of picosecond CO{sub 2} lasers, operating at 10 {mu}m wavelength, and their applications for strong-field physics research. Such laser has been used in a number of BNL ...experiments that explore advanced methods of particle acceleration and X-ray generation. We illustrate merits of the wavelength scaling from optical to mid-IR region by the examples of ion/proton acceleration and report the first experimental results that confirm the expected wavelength scaling of the process.
Test-beam aging studies of a TMAE prototype for the HERA-B RICH Lau, K.; Atiya, M.; Broemmelsiek, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2003, Letnik:
515, Številka:
1
Journal Article
Recenzirano
The aging properties of a wire chamber, operating in a methane/TMAE gas mixture, were studied in a beam test. We emphasize here the precautions taken to minimize aging due to materials used in the ...chamber, and the redundancy in the design of the test. We compare our aging results to those recorded in the literature and find good agreement in the overall aging properties as a function of dose. We also report the results of increasing the high voltage of the aged chamber to restore the gain.
BoNus: Development and use of a radial TPC using cylindrical GEMs Fenker, H.; Baillie, N.; Bradshaw, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2008, Letnik:
592, Številka:
3
Journal Article
Recenzirano
Odprti dostop
A specialized system of target and detector was developed at Jefferson Lab to provide new access to information about neutron structure from electron–neutron interactions. It allows identification ...and measurement of spectator protons produced in
e
-
d
→
e
-
p
s
X
scattering events. The detector is a radial time-projection chamber optimized for the acceptance of low-momentum protons. Gas gain is provided by three cascaded curved Gas Electron Multipliers (GEMs), the first application of GEMs in any configuration other than flat. This article provides details about the development and construction of the detector, its performance, and the analysis of the data from the successful running of its first physics experiment.
A study of the angular distributions of leptons from decays of
J
/
ψ
’s produced in p-C and p-W collisions at
has been performed in the
J
/
ψ
Feynman-
x
region −0.34<
x
F
<0.14 and for
J
/
ψ
...transverse momenta up to 5.4 GeV/
c
. The data were collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The results, based on a clean selection of 2.3×10
5
J
/
ψ
’s reconstructed in both the
e
+
e
−
and
μ
+
μ
−
decay channels, indicate that
J
/
ψ
’s are produced polarized. The magnitude of the effect is maximal at low
p
T
. For
p
T
>1 GeV/
c
a significant dependence on the reference frame is found: the polar anisotropy is more pronounced in the Collins-Soper frame and almost vanishes in the helicity frame, where, instead, a significant azimuthal anisotropy arises.
We have searched for Theta+(1540) and Xi(--)(1862) pentaquark candidates in proton-induced reactions on C, Ti, and W targets at midrapidity and square root of s = 41.6 GeV. In 2 x 10(8) inelastic ...events we find no evidence for narrow (sigma approximately 5 MeV) signals in the Theta+ --> pK0(S) and Xi(--) --> Xi- pi- channels; our 95% C.L. upper limits (UL) for the inclusive production cross section times branching fraction B dsigma/dy/(y approximately 0) are (4-16) mub/N for a Theta+ mass between 1521 and 1555 MeV, and 2.5 mub/N for the Xi(--). The UL of the yield ratio of Theta+/Lambda(1520) < (3-12)% is significantly lower than model predictions. Our UL of B Xi(--)/Xi(1530)0 < 4% is at variance with the results that have provided the first evidence for the Xi(--).
The spectral and angular distributions, as well as the total number of photons of gammaray Cherenkov-transition radiation (GCTR) produced by charged particles in the photon energy region (0.8–2) MeV, ...are calculated using the results of the recent discovery that in the above-mentioned region the refraction index of some materials is greater than unity,
n
(ω) > 1, due to Delbruck scattering on Coulomb field of nuclei. Using the results of the numerical calculations carried out, we propose an experimental arrangement for observation and study of GCTR produced by electrons with energy much higher than the threshold energy of GCTR (∼10 GeV). Some applications of GCTR, in particular, the search for new materials with
n
(ω) > 1 in gamma region with the help of this method, are discussed.
Crystalline wigglers Ispirian, K.A.; Ispiryan, M.K.
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
June 2006, 2006-06-00, Letnik:
247, Številka:
2
Journal Article
Recenzirano
It is proposed to use a stack of thin crystalline plates the crystallographic planes of which make the “periodical channels” necessary for oscillatory motion of the channeled positively charged ...relativistic particles. Coming out from the previous plate the particles can be bent and captured into channeling mode in the next one or in a few plates. The channeled particles besides the harder channeling radiation in the plates generate wiggler radiation. Compared with the magnetic wigglers the proposed small crystalline wigglers have smaller curvature radius due to the much stronger crystalline fields. Compared with the existing or proposed crystalline undulators the proposed devices have much simpler construction and larger acceptances.
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