Mohsen Khakzad

The goal of this report is to give a comprehensive overview of the rich field of forward physics, with a special attention to the topics that can be studied at the LHC. The report starts presenting a selection of the Monte Carlo simulation tools currently available, chapter 2, then enters the rich phenomenology of QCD at low, chapter 3, and high, chapter 4, momentum transfer, while the unique scattering conditions of central exclusive production are analyzed in chapter 5. The last two experimental topics, Cosmic Ray and Heavy Ion physics are presented in the chapter 6 and 7 respectively. Chapter 8 is dedicated to the BFKL dynamics, multiparton interactions, and saturation. The report ends with an overview of the forward detectors at LHC. Each chapter is correlated with a comprehensive bibliography, attempting to provide to the interested reader with a wide opportunity for further studies.

Forward calorimeters, located near the incident beams, complete the nearly 4π coverage for high pT particles resulting from proton-proton collisions in the ATLAS detector at the Large Hadron Collider at CERN. Both the technology and the deployment of the forward calorimeters in ATLAS are novel. The liquid argon rod/tube electrode structure for the forward calorimeters was invented specifically for applications in high rate environments. The placement of the forward calorimeters adjacent to the other calorimeters relatively close to the interaction point provides several advantages including nearly seamless calorimetry and natural shielding for the muon system. The forward calorimeter performance requirements are driven by events with missing ET and tagging jets.

SiPMs operate in Geiger mode, wherein photodiode cells are reverse-biased to the breakdown by even a single photon. Each cell is connected in series with a quenching resistor, which prevents cell damage and resets the cell after making a signal. All cells are arranged in parallel, making SiPMs and biasing circuits vulnerable to over-illumination, where the current passing through the SiPM can exceed the allowable value, leading to damage. In this study, we investigate over-current conditions in SiPMs and propose a protective method against over-illumination and over-current using a series resistor. Additionally, we ensure SiPM stability through the incorporation of a suitable capacitor.

The pseudorapidity region 2.5<|η|<4.0 in ATLAS is a particularly complex transition zone between the endcap and forward calorimeters. A set-up consisting of 14 resp. 18 of the full azimuthal acceptance of the ATLAS liquid argon endcap and forward calorimeters has been exposed to beams of electrons, pions and muons in the energy range E⩽200GeV at the CERN SPS. Data have been taken in the endcap and forward calorimeter regions as well as in the transition region. This beam test set-up corresponds very closely to the geometry and support structures in ATLAS. A detailed study of the performance in the endcap and forward calorimeter regions is described. The data are compared with MC simulations based on GEANT 4 models.

One of the two ATLAS Forward Calorimeters (FCal), consisting of three modules, one behind the other, was exposed to particle beams of known energies in order to obtain the energy calibration. The data were taken in the H6 beamline at CERN in the summer of 2003, using electron and hadron beams with energies from 10 to 200 GeV. The beam test setup and collected data samples are described in detail. Using data samples taken with a minimal amount of material upstream of the calorimeter, the FCal response to electrons and pions, as measured by the linearity and resolution as a function of energy, is extracted and compared to ATLAS performance requirements.

A lead scintillator sandwich sampling calorimeter has been installed in the HERA tunnel 105.6 m from the central ZEUS detector in the proton beam direction.It is designed to measure the energy and scattering angle of neutrons produced in charge exchange ep collisions.Before installation the calorimeter was tested and calibrated in the H6 beam at CERN where 120 GeV electrons, muons, pions and protons were made incident on the calorimeter.In addition, the spectrum of fast neutrons from charge exchange proton-lucite collisions was measured.The design and construction of the calorimeter is described, and the results of the CERN test reported.Special attention is paid to the measurement of shower position, shower width, and the separation of electromagnetic showers from hadronic showers.The overall energy scale as determined from the energy spectrum of charge exchange neutrons is compared to that obtained from direct beam hadrons.

The local hadronic calibration scheme developed for the reconstruction and calibration of jets and missing transverse energy in ATLAS has been evaluated using data obtained during combined beam tests of modules of the ATLAS liquid argon endcap and forward calorimeters. These tests covered the pseudorapidity range of 2.5<|η|<4.0. The analysis has been performed using special sets of calibration weights and corrections obtained with the Geant4 simulation of a detailed beam-test setup. The evaluation itself has been performed through the careful study of specific calorimeter performance parameters such as e.g. energy response and resolution, shower shapes, as well as different physics lists of the Geant4 simulation.

Abstract The signals received from the optical receivers like SiPM and PMT due to the collision of energetic particles with the scintillators attached to these optical receivers are weak and fast. Optimizing signals is necessary to measure the number of signals and their peak height with electronic circuits. This text presents an example of SiPM's driver circuit, signal counting, and peak measurement. Also, the electronic circuits necessary to optimize the signals, including amplification, removing background noise, converting the signal to digital, and increasing the duration of the signal, are presented in this text. In the end, we provide two tests to confirm the correct operation of the circuits. Such a system has several advantages. This set has a small volume and is portable. Its operating voltage is 12 volts, with a current of about 0.3 amps; as a result, it is easily possible to use this set in any experiment. In addition, the cost of building such a system is much lower than providing similar ready-made designs. The most important achievement here is to convert the standard signal taken from the detector into an almost ideal optimized signal for signal counting and peak measurement. Therefore, it seems that using all or part of these circuits can be helpful for researchers. This text presents a particular method for signal optimization and provides the reader with a coherent and complete process of building and testing circuits. If the reader is familiar with the basics of electronics and detectors, they can reconstruct the circuits without any problems. Therefore, parts of this text may have an educational and review form.

Photomultiplier tube (PMT) and Silicon Photo Multiplier (SiPM) are often used for detecting small number of photons or very weak radiations. A light guide usually connects these photodetectors to the test space. In this article, we investigate the effect of background signals caused by cosmic muons scintillation or interactions with PMT and SiPM, their light guide or input window materials. We study such interactions by making simulations using GATE software package and undertaking experiments using detector circuits developed as in~\cite{Raki:2022lwn}. The background cosmic muons can generate photons which will lead to errors in low radiation and single photon detection experiments especially if standard scintillators are not used. For such experiments, we conclude that the most useful method for cutting down the cosmic muons background should be by conducting the experiments deep underground or inside tunnels with several tens of meters of materials above it.

Abstract Photomultiplier tube (PMT) and Silicon Photo Multiplier (SiPM) are often used for detecting small number of photons or very weak radiations. A light guide usually connects these photodetectors to the test space. In this article, we investigate the effect of background signals caused by cosmic muons scintillation or interactions with PMT and SiPM, their light guide or input window materials. We study such interactions by making simulations using GATE software package and undertaking experiments using detector circuits developed as in [1]. The background cosmic muons can generate photons which will lead to errors in low radiation and single photon detection experiments especially if standard scintillators are not used. For such experiments, we conclude that the most useful method for cutting down the cosmic muons background should be by conducting the experiments deep underground or inside tunnels with several tens of meters of materials above it.

A digital data acquisition system together with MATLAB software for data analysis were utilised to measure the pulse specification of the scintillation detector assembly. Besides, the sensitivity of a photomultiplier tube (PMT) window to gamma-rays was studied to discriminate the signals produced as a result of gamma-ray interactions inside the glass window from those originating from the scintillator cell. The result showed that an algorithm based on the time features was capable to evaluate the contributions of these two different signals.

We report a measurement of the exclusive production of pairs of charged pions in proton-proton collisions, dominated by the process pp → p ( * ) π + π -p ( * ) , where p ( * ) stands for a diffractively dissociated proton, the π + π -pair is emitted at central rapidities y, and the incident protons stay intact or dissociate without detection p ( * ) .The measurement is performed with the CMS detector at the LHC, using a data sample corresponding to an integrated luminosity of 450 µb -1 collected at a center-of-mass energy of √ s = 7 TeV in 2010.The cross section measured in the phase * Speaker.

We report a measurement of the exclusive production of pairs of charged pions in proton-proton collisions, dominated by the process $pp \rightarrow p^{(*)} \pi^{+}\pi^{-} p^{(*)}$, where $\rm p^{(*)}$ stands for a diffractively dissociated proton, the $\pi^{+} \pi^{-}$ pair is emitted at central rapidities $y$, and the incident protons stay intact or dissociate without detection ${\rm p^{(*)}}$. The measurement is performed with the CMS detector at the LHC, using a data sample corresponding to an integrated luminosity of 450~$\mu$b$^{-1}$ collected at a center-of-mass energy of $\sqrt{s}$ = 7 TeV in 2010. The cross section measured in the phase space defined by pion transverse momentum $p_{\rm T}>0.2$~GeV/c and rapidity $|y|< 2 $ is found to be $20.5~\pm~0.3~(\rm {stat})~(\pm~3.1~\rm {syst})~\pm$~0.8~(lumi)~$\mu$b. The differential cross sections for $\pi^{+}\pi^{-}$ pairs as a function of the pion pair invariant mass, $p_{\rm T}$, and $y$, as well as a single-pion differential cross section as a function of pion $p_{\rm T}$ are also measured and compared to several phenomenological predictions.

We report a measurement of the exclusive production of pairs of charged pions in proton-proton collisions, dominated by the process $pp \rightarrow p^{(*)} \pi^{+}\pi^{-} p^{(*)}$, where $\rm p^{(*)}$ stands for a diffractively dissociated proton, the $\pi^{+} \pi^{-}$ pair is emitted at central rapidities $y$, and the incident protons stay intact or dissociate without detection ${\rm p^{(*)}}$. The measurement is performed with the CMS detector at the LHC, using a data sample corresponding to an integrated luminosity of 450~$\mu$b$^{-1}$ collected at a center-of-mass energy of $\sqrt{s}$ = 7 TeV in 2010. The cross section measured in the phase space defined by pion transverse momentum $p_{\rm T}>0.2$~GeV/c and rapidity $|y|< 2 $ is found to be $20.5~\pm~0.3~(\rm {stat})~(\pm~3.1~\rm {syst})~\pm$~0.8~(lumi)~$\mu$b. The differential cross sections for $\pi^{+}\pi^{-}$ pairs as a function of the pion pair invariant mass, $p_{\rm T}$, and $y$, as well as a single-pion differential cross section as a function of pion $p_{\rm T}$ are also measured and compared to several phenomenological predictions.

One of two ATLAS Forward Calorimeters, consisting of three modules, one behind the other, was exposed to particle beams of known energies in order to study the detector performance with and without the presence of upstream material in the beam, and at the inner edge of the acceptance where shower energy containment is incomplete.Data were taken in the H6 beamline at CERN using electron and hadron beams with energies from 10 to 200 GeV.Results related to the intrinsic detector calibration, based on data taken with a minimal amount of material in front of the detector, have been previously published, but are updated here.This paper focuses on studies of data taken with additional upstream material in place.The effects of this additional material on the linearity and resolution of the response are presented.The response at the inner edge of the acceptance is also investigated.For all analyses, results based on a GEANT4 simulation of the beam-test setup and detector response are also presented.

A search for exclusive or quasi-exclusive γγ → W+W− production, pp → p(∗)W+W−p(∗) → p(∗)μ±e∓p(∗), at s=8TeV (7 TeV) is reported using data corresponding to an integrated luminosity of 19.7 fb−1 (5.5fb−1), respectively. In this study, we look for any deviations that there might be from the Standard Model, and the results are used to set limits on the Anomalous Quartic Gauge Couplings. We also report a measurement of the exclusive production of pairs of charged pions in proton-proton collisions. The differential cross sections for π+π− pairs as a function of the pion pair invariant mass is measured and compared to several phenomenological predictions.

The construction of the ATLAS liquid argon calorimeter mechanical components has been completed and the focus has switched to integration and commissioning. In this paper we briefly review the status of the ATLAS liquid argon system and the plans for preparing it for data taking within ATLAS.

Dijet differential cross sections for the reaction e+p → e++jet+jet+n+X in the photoproduction regime have been measured with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb−1. The cross sections are given for jet transverse energies ETjet > 6 GeV, neutron energy En > 400 GeV, and neutron angle θn < 0.8 mrad with respect to the proton direction. The fraction of events with a leading neutron in the final state is shown. The predictions of the one pion exchange model are found to be in reasonable agreement with the measurements presented, namely the dijet cross section as a function of the jet transverse energies, the jet pseudorapidities, and the fraction of the momentum of a postulated exchanged pion participating in the production of the dijet system.