Data taking and analysis infrastructures in HEP (High Energy Physics) have evolved during many years to a well known problem domain. In contrast to HEP, third generation synchrotron light sources, ...existing and upcoming free electron lasers are confronted with an explosion in data rates driven primarily by recent developments in 2D pixel array detectors. The next generation of detectors will produce data in the region upwards of 50 Gbytes per second. At synchrotrons, data was traditionally taken away by users following data taking using portable media. This will clearly not scale at all. We present first experiences of our new architecture and underlying services based on results taken from the resumption of data taking in April 2015. Technology choices were undertaking over a period of twelve month. The work involved a close collaboration between central IT, beamline controls, and beamline support staff. In addition a cooperation was established between DESY IT and IBM to include industrial research and development experience and skills. Our approach integrates HPC technologies for storage systems and protocols. In particular, our solution uses a single file-system instance with a multiple protocol access, while operating within a single namespace.
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.
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
.
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(--).
Ratios of the ψ′ over the J/ψ production cross sections in the dilepton channel for C, Ti and W targets have been measured in 920 GeV proton-nucleus interactions with the HERA-B detector at the HERA ...storage ring. The ψ′ and J/ψ states were reconstructed in both the μ+μ- and the e+e- decay modes. The measurements covered the kinematic range -0.35≤xF≤0.1 with transverse momentum pT≤4.5 GeV/c. The angular dependence of the ratio has been used to measure the difference of the ψ′ and J/ψ polarization. All results for the muon and electron decay channels are in good agreement: their ratio, averaged over all events, is Rψ′(μ)/Rψ′(e)=1.00±0.08±0.04. This result constitutes a new, direct experimental constraint on the double ratio of branching fractions, (B′(μ)B(e))/(B(μ)B′(e)), of ψ′ and J/ψ in the two channels. The ψ′ to J/ψ production ratio is almost constant in the covered xF range and shows a slow increase with pT.
is a fixed target experiment working on the 920 GeV proton beam of the HERA accelerator at the DESY laboratory in Hamburg. During the last data taking period (2002-2003), about 150 million dilepton ...triggers, 220 million minimum bias events and 35 million hard photon triggers were acquired. These large statistics allow detailed studies on the production of charmonium states in proton-nucleus p-A collisions, which extend for the first time into the negative Feynman-x () region. Measurements of the inclusive , \(\Upsilon\) and open charm cross sections are also ongoing. After a brief discussion of the detector and of the data samples, we report on preliminary results obtained on these physics topics.
Inclusive doubly differential cross sections d2σpA/dxF dpT2 as a function of Feynman-x (xF) and transverse momentum (pT) for the production of KS0, Λ and \(\bar{\varLambda}\) in proton-nucleus ...interactions at 920 GeV are presented. The measurements were performed by HERA-B in the negative xF range (−0.12<xF<0.0) and for transverse momenta up to pT=1.6 GeV/c. Results for three target materials: carbon, titanium and tungsten are given. The ratios of production cross sections are presented and discussed. The Cronin effect is clearly observed for all three V0 species. The atomic number dependence is parameterized as σpA=σpN⋅Aα where σpN is the proton-nucleon cross section. The measured values of α are all near one. The results are compared with EPOS 1.67 and PYTHIA 6.3. EPOS reproduces the data to within ≈20% except at very low transverse momentum.
Inclusive doubly differential cross sections d super(2) s sub(pA )/dx sub(F ) dp sub(T ) super(2) as a function of Feynman-x (x sub(F )) and transverse momentum (p sub(T )) for the production of K ...sub(S ) super(0) , and $\bar{\varLambda}$ in proton-nucleus interactions at 920 GeV are presented. The measurements were performed by HERA-B in the negative x sub(F )range (-0.12<x sub(F )<0.0) and for transverse momenta up to p sub(T )=1.6 GeV/c. Results for three target materials: carbon, titanium and tungsten are given. The ratios of production cross sections are presented and discussed. The Cronin effect is clearly observed for all three V super(0) species. The atomic number dependence is parameterized as s sub(pA )=s sub(pN ); A super(a )where s sub(pN )is the proton-nucleon cross section. The measured values of a are all near one. The results are compared with EPOS 1.67 and PYTHIA 6.3. EPOS reproduces the data to within -20% except at very low transverse momentum.
The inclusive production cross sections of the charmed mesons D0,D+,Ds+ and D*+ have been measured in interactions of 920 GeV protons on C, Ti, and W targets with the HERA-B detector at the HERA ...storage ring. Differential cross sections as a function of transverse momentum and Feynman’s x variable are given for the central rapidity region and for transverse momenta up to pT=3.5 GeV/c. The atomic mass number dependence and the leading to non-leading particle production asymmetries are presented as well.
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