228 research outputs found
GeMSE: A new Low-Background Facility for Meteorite and Material Screening
We are currently setting up a facility for low-background gamma-ray
spectrometry based on a HPGe detector. It is dedicated to material screening
for the XENON and DARWIN dark matter projects as well as to the
characterization of meteorites. The detector will be installed in a medium
depth (620 m.w.e.) underground laboratory in Switzerland with several
layers of shielding and an active muon-veto. The GeMSE facility will be
operational by fall 2015 with an expected background rate of 250
counts/day (100-2700 keV).Comment: The following article appeared in AIP Conf. Proc. 1672, 120004 (2015)
and may be found at
http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.4928010. The
muon spectrum in Figure 4 (left) was corrected due to a bug in the code.
After correction the muon flux is reduced by a factor of about
Single spin asymmetries in DIS
We consider possible mechanisms for single spin asymmetries in inclusive Deep
Inelastic Scattering (DIS) processes with unpolarized leptons and transversely
polarized nucleons. Tests for the effects of non-zero \bfk_\perp, for the
properties of spin dependent quark fragmentations and for quark helicity
conservation are suggested.Comment: 5 pages, LaTeX, no figures. Revised version, to be published in Phys.
Rev. D. Some equations and statements added to clarify text and notation
Accessing transversity via J/Psi production in polarized p-pbar interactions
We discuss the possibility of a direct access to transversity distributions
by measuring the double transverse spin asymmetry A_TT in p pbar --> J/Psi + X
--> l^- l^+ + X processes at future GSI-HESR experiments with polarized protons
and anti-protons. In the J/Psi resonance production region, with 30 < s < 45
GeV^2, both the cross-section and A_TT are expected to be sufficiently large to
allow a measurement of h_1^q(x,M^2); numerical estimates are given.Comment: 10 pages, 2 figures. Version accepted for publication in PLB;
comments and references adde
On asymmetry in inclusive pion production
On the basis of the mechanism proposed for one-spin asymmetries in inclusive
hadron production we specify an --dependence of asymmetries in inclusive
processes of pion production. The main role in generation of this asymmetry
belongs to the orbital angular momentum ofquark-antiquark cloud in internal
structure of constituent quarks. The --dependence of asymmetries in the
charged pion production at large reflects the corresponding dependence of
constituent quark polarization in the polarized proton.Comment: LaTeX, 8 pages, 3 figures. One figure added, as it appears in Phys.
Rev.
Accessing Transversity in Double-Spin Asymmetries at the BNL-RHIC
We give upper bounds for transverse double-spin asymmetries in polarized
proton-proton collisions by saturating the positivity constraint for the
transversity densities at a low hadronic resolution scale. We consider prompt
photon, jet, pion, and heavy flavor production at the BNL Relativistic Heavy
Ion Collider (RHIC). Estimates of the expected statistical accuracy for such
measurements are presented, taking into account the acceptance of the RHIC
detectors.Comment: 15 pages, LaTeX, 2 figures as eps file
Polarization in Hadronic \Lambda Hyperon Production and Chiral-Odd Twist-3 Distribution
Polarization of the \Lambda hyperon produced with a large transverse momentum
in the unpolarized nucleon-nucleon collision is analyzed in the framework of
QCD factorization. We focus on the mechanism in which the soft-gluon component
of the chiral-odd spin-independent twist-3 quark distribution E_F(x,x) becomes
a source of the polarized quark fragmenting into the polarized \Lambda. Our
simple model estimate for this contribution indicates that it gives rise to a
significant \Lambda polarization at large x_F. This is in parallel with the
observation that the soft gluon pole mechanism gives rise to a large single
transverse spin asymmetry in the pion production at x_F\to 1.Comment: 10 pages in LaTex + 5 figures in PS files. Phys. Rev. D in press.
Title changed and some discussions adde
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