The ALICE collaboration is investigating single, double and central diffractive processes in pp interactions. The single and double diffractive cross-sections are presented at 900 GeV 2.76 TeV and 7 ...TeV using an analysis method based on the classification of diffractive gaps. Promising early results on central diffractive processes have motivated the use of additional diffractive counters, which are currently being installed.
Photons produced in pp interactions at 450 GeV/c were detected by reconstructing the e+e− pairs of photon conversions in a 1 mm thick lead sheet placed in front of the MWPCs of the OMEGA spectrometer ...at CERN. A soft photon signal 4.1±0.8 times the inner bremsstrahlung prediction was observed in the forward rapidity region (yc.m.s.⩾1.2), thus extending the domain of the anomalous soft photon effect seen already in K+p, π+p and π−p interactions.
The integration of the ALICE trigger system with sub-detectors Krivda, M.; Barnby, L.; Bombara, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
The ALICE Trigger electronics (TRG) has been installed in the experimental cavern and tested with each of the detectors, both individually (‘standalone’ mode) and in ‘global’ runs, i.e. those ...involving other detectors. Global runs were performed with cosmic ray triggers, and also during the LHC startup period in September 2008. In this paper the status of the trigger system will be reviewed, in particular describing recent extensions to the system.
Resonance production at ALICE: ρ and ϕ Bhasin, A.; Evans, D.; Jones, G. T. ...
Indian journal of physics,
12/2010, Letnik:
84, Številka:
12
Journal Article
Recenzirano
Resonances in heavy ion experiments provide information about the medium produced in the collisions, in particular about the later stages in the evolution of the fireball. The motivation for the ...study of resonances at ALICE, specifically the
ρ
and
ϕ
mesons, is discussed. The findings of Monte Carlo studies for
ρ
produced in Pb-Pb collisions are outlined, and a fit to the
π
+
π
−
spectrum, including other contributions, is presented. The
ϕ
shape, which shows some distortion, is discussed. The
ρ
meson has a narrow width, making it more easily visible, so its significance without Particle IDentification, or PID, has been investigated. Recent work on the ϕ meson in simulated pp collisions is described, including a fit to the K
+
K
−
spectrum with no PID.
ALICE will measure the properties of strongly interacting matter created in heavy-ion collisions. In addition, taking advantage of the low
p
t
acceptance in the central barrel, ALICE will play an ...important role in understanding
pp
collisions with minimum bias triggers at LHC energies. The proposed minimum bias trigger is sensitive to about 90% of the total inelastic cross section and 99% of the non-diffractive cross section. A procedure to calculate the trigger efficiency and an estimate of the systematic uncertainty due to the limited acceptance of the detector are presented.
The reaction pp -> pf (eta eta) ps has been studied at 450 GeV/c. For the first time a partial wave analysis of the centrally produced eta eta system has been performed. Signals for the f0(1500), ...f0(1710) and f2(2150) are observed and the decay branching fractions of these states are determined.
The reactions
pp→
p
f
(
X
0)
p
s
, where
X
0 is observed decaying to
π
0
π
0
π
0
π
0 ,
π
+
π
−
π
+
π
− and
π
+
π
−
π
0
π
0 , have been studied at 450 GeV/
c. There is evidence for an
a
2(1320)
π ...decay mode of the
η
2(1645) and
η
2(1870) in the
π
+
π
−
π
0
π
0 and
π
+
π
−
π
+
π
− final states. The
f
2(1950) is consistent with being a single resonance with a dominant
f
2(1270)
ππ decay mode. The
f
0(1370) is found to decay dominantly to
ρρ while the
f
0(1500) is found to decay to
ρρ and
σσ.
The ALICE Central Trigger Processor (CTP) is going to be upgraded for LHC Run 3 with completely new hardware and a new Trigger and Timing Control (TTC-PON) system based on a Passive Optical Network ...(PON) system. The new trigger system has been designed as dead time free and able to transmit trigger data at 9.6 Gbps. A new universal trigger board has been designed, where by changing the FMC card, it can function as a CTP or as a LTU. It is based on the Xilinx Kintex Ultrascale FPGA and upgraded TTC-PON. The new trigger system and the prototype of the trigger board will be presented.
PDF
