Recent results from HERA Tokushuku, K.
Nuclear physics. A,
08/1998, Volume:
638, Issue:
1
Journal Article
Peer reviewed
Recent measurements from HERA collider experiments at DESY were presented. The talk includes measurements of the proton structure functions in a wide kinematic region in
Q
2 and
x, extractions of the ...gluon distribution in the proton from various processes and heavy quark productions. The results are compared with models based on the perturbative quantum chromodynamics (pQCD).
Small x physics at HERA Tokushuku, K.
Nuclear physics. A,
02/1998, Volume:
629, Issue:
1
Journal Article
Peer reviewed
Recent measurements of the structure function
F
2 in
e
+p
scattering at HERA were presented for a wide range of
Q
2
and
x. The rapid rise of
F
2 with decreasing
x has been confirmed with high ...statistical data obtained in 1994. In the measurements, the
Q
2 range was extended down to 1.5GeV
2. The rise corresponds to the rapid increase of the total virtual photon-proton cross section at high energies. On the other hand, the total cross section of photon-proton interaction at
Q
2 = 0 has no strong energy dependence. H1 and ZEUS performed new
F
2 measurements for
Q
2 < 1GeV
2 with upgraded detectors in order to study the transition region. The results were shown and compared to predictions of various models.
At large values of x , the parton distribution functions (PDFs) of the proton are poorly constrained and there are considerable variations between different global fits. Data at such high x have ...already been published by the ZEUS Collaboration, but not yet used in PDF extractions. A technique for comparing predictions based on different PDF sets to the observed number of events in the ZEUS data is presented. It is applied to compare predictions from the most commonly used PDFs to published ZEUS data at high Bjorken x . A wide variation is found in the ability of the PDFs to predict the observed results. A scheme for including the ZEUS highx data in future PDF extractions is discussed.
The ATLAS Muon Trigger "Slice" Sidoti, A.; Bellomo, M.; Biglietti, M. ...
IEEE transactions on nuclear science,
02/2008, Volume:
55, Issue:
1
Journal Article
Peer reviewed
The ATLAS experiment at the Large Hadron Collider (LHC) will face the challenge of selecting interesting candidate events in proton-proton collisions at 14 TeV center of mass energy, while rejecting ...the enormous number of background events. The trigger system architecture is organized in three levels. From a bunch crossing rate of 40 MHz, the First Level trigger, hardware implemented, will reduce this rate to around ~75 kHz. Then the software based High Level Trigger (HLT), composed by the Second Level Trigger and the Event Filter reduces the rate to 200 Hz. In this paper, we will present the implementation of the muon trigger ldquoslice,rdquo signal efficiencies, background rejection rates, and system performances (execution time, memory consumption, etc.) for online muon selection based on Monte Carlo simulations and results obtained on real events collected during cosmic data taking runs.
Analog readout modules for the ZEUS microvertex detector Fusayasu, T.; Tokushuku, K.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/1999, Volume:
436, Issue:
1
Journal Article
Peer reviewed
Analog readout modules have been developed for a silicon microvertex detector of the electron–proton collision experiment ZEUS. Analog signals kept in the front end are read out and digitized by ADCs ...and processed afterwards to reduce the data volume while keeping the signal information. We have developed prototype modules with 10-bit 10
MHz ADCs and digital processors built in Field Programmable Gate Arrays. Their performance was investigated.
Production of exclusive dijets in diffractive deep inelastic Formula omitted scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb Formula omitted. The ...measurement was performed for Formula omitted-p centre-of-mass energies in the range Formula omitted and for photon virtualities Formula omitted. Energy flows around the jet axis are presented. The cross section is presented as a function of Formula omitted and Formula omitted, where Formula omitted, x is the Bjorken variable and Formula omitted is the proton fractional longitudinal momentum loss. The angle Formula omitted is defined by the Formula omitted-dijet plane and the Formula omitted- Formula omitted plane in the rest frame of the diffractive final state. The Formula omitted cross section is measured in bins of Formula omitted. The results are compared to predictions from models based on different assumptions about the nature of the diffractive exchange.
A Forward Plug Calorimeter (FPC) for the ZEUS detector at HERA has been built as a shashlik lead–scintillator calorimeter with wave length shifter fiber readout. Before installation it was tested and ...calibrated using the X5 test beam facility of the SPS accelerator at CERN. Electron, muon and pion beams in the momentum range of 10–100 GeV/
c were used. Results of these measurements are presented as well as a calibration monitoring system based on a
60Co source.
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