Multiplicity Studies and Effective Energy in ALICE at the LHC

In this work we explore the possibility to perform ``effective energy'' studies in very high energy collisions at the CERN Large Hadron Collider (LHC). In particular, we focus on the possibility to measure in $pp$ collisions the average charged multiplicity as a function of the effective energy with the ALICE experiment, using its capability to measure the energy of the leading baryons with the Zero Degree Calorimeters. Analyses of this kind have been done at lower centre--of--mass energies and have shown that, once the appropriate kinematic variables are chosen, particle production is characterized by universal properties: no matter the nature of the interacting particles, the final states have identical features. Assuming that this universality picture can be extended to {\it ion--ion} collisions, as suggested by recent results from RHIC experiments, a novel approach based on the scaling hypothesis for limiting fragmentation has been used to derive the expected charged event multiplicity in $AA$ interactions at LHC. This leads to scenarios where the multiplicity is significantly lower compared to most of the predictions from the models currently used to describe high energy $AA$ collisions. A mean charged multiplicity of about 1000-2000 per rapidity unit (at $\eta \sim 0$) is expected for the most central $Pb-Pb$ collisions at $\sqrt{s_{NN}} = 5.5 TeV$.Comment: 12 pages, 19 figures. In memory of A. Smirnitski

Results from a large sample of MRPC-strip prototypes for the ALICE TOF detector

The MRPC (multi resistive plate chamber) strip is the basic element of the ALICE time-of-flight detector. A test of a large sample of MRPC-strip prototypes corresponding to 1.2% of the full detector was carried out during the autumn of 2002 at the CERN proton syncroton facility. This paper summarizes the main results obtained in terms of uniformity of response for all the tested channels

Operation of the Multigap Resistive Plate Chamber using a gas mixture free of flammable components

We have investigated the operation of the multigap resistive plate chamber (MRPC) for the ALICE-TOF system with a gas mixture free of flammable components. Two different gas mixtures, with and without iso-C4H10 have been used to measure the performance of the MRPC. The efficiency, time resolution, total charge, and the fast to total charge ratio have been found to be comparabl

Structural Assembly from Phosphate to Germanophosphate by Applying Germanate as a Binder

National Natural Science Foundation of China [21201144, 21233004, 40972035]; Fundamental Research Funds for the Central Universities [2013121020]; Technological Innovation Platform of Fujian Province [2006L2003]Structural assembly from phosphate to germanophosphate by applying germanate as a binder has been achieved. Two isotypic porous compounds, K-3 [M-4(II)(HPO4)(2)][Ge2O(OH)(PO4)(4)]center dot xH(2)O (M-II = Fe, Cd; x = 2 for Fe and 3 for Cd, denoted as KFeGePO-1 and KCdGePO-1, respectively), contain a known transition-metal phosphate (TMPO) layer, (2)(infinity){[M-2(HPO4)(3)](2-)}, which is built from chains of trans-edge-sharing MO6 octahedra bridged by MO5 trigonal bipyramids that were further linked and decorated by phosphate tetrahedra. The layers are bound by infinite chains of GeO5(OH) octahedra, resulting in a 3D open-framework structure with 1D 12-ring channels that are occupied by K+ ions and water molecules. The curvature of the TMPO layers and shape of the 12-ring windows can be tuned by the transition metals because of their Jahn-Teller effect

Particle identification with the ALICE TOF detector at very high multiplicity

A procedure developed to achieve particle identification in very high multiplicity conditions using a complex time-of-flight system is illustrated in detail by simulating and studying the performance of the ALICE TOF detector in a realistic scenario of Pb-Pb and p-p interactions at LHC

Latest results on the performance of the multigap resistive plate chamber used for the ALICE TOF

For the identification of particles in the momentum range 0.5-2.5GeV/c, the ALICE experiment uses a Time Of Flight array consisting of Multigap Resistive Plate Chambers (MRPC) in the form of long strips. The design of the detector elements is as follows : double stack MRPCs with glass resistive plates and 5 gas gaps of 250 mum per stack. The latest results on the performance of these MRPCs are presented. Typical values of time resolution a are better than 50 ps, with an efficiency of 99.9% and a long, more than 1.5 kV, streamer-free plateau

Operation of the multigap resistive plate chamber using a gas mixture free of flammable components

We have investigated the operation of the multigap resistive plate chamber (MRPC) for the ALICE-TOF system with a gas mixture free of flammable components. Two different gas mixtures, with and without iso-C//4H//1//0 have been used to measure the performance of the MRPC. The efficiency, time resolution, total charge, and the fast to total charge ratio have been found to be comparable

Latest results on the performance of the multigap resistive plate chamber used for the ALICE TOF

For the identification of particles in the momentum range 0.5-2.5 GeV /c, the ALICE experiment uses a Time Of Flight array consisting of Multigap Resistive Plate Chambers (MRPC) in the form of long strips. The design of the detector elements is as follows: double stack MRPCs with glass resistive plates and 5 gas gaps of 250 mum per stack. The latest results on the performance of these MRPCs are presented. Typical values of time resolution sigma are better than 50 ps, with an efficiency of 99.9% and a long, more than 1.5kV, streamer-free plateau

Study of gas mixtures and ageing of the multigap resistive plate chamber used for the ALICE TOF

We present in this paper a study of the ALICE-TOF Multigap Resistive Plate Chamber (MRPC) performance by using several gas mixtures. We also present a search for possible ageing effects, by studying two MRPCs irradiated at the CERN Gamma Irradiation Facility