Test Beam Data Research Articles

Determining the Jet Energy Scale uncertainty in the ATLAS detector

Using jets from proton–proton collisions at a centre of mass energy of s=7TeV measured with the ATLAS detector at the LHC the Jet Energy Scale and its systematic uncertainty have been determined. Using 2010 data a Jet Energy Scale systematic uncertainty between 2–4% for jet pT>20GeV in the pseudo-rapidity region up to |η|=4.5 has been obtained. This uncertainty was derived from a combination of systematic variations in Monte Carlo simulations and single hadron response measurements performed in situ and using test beam data. The uncertainty is confirmed in in situ methods using 2011 data where a well measured reference object is balanced against the jet.

Measurements of cosmic-ray proton and helium spectra with the PAMELA calorimeter

We present a new measurement of the cosmic ray proton and helium spectra by the PAMELA experiment performed using the “thin” (in terms of nuclei interactions) sampling electromagnetic calorimeter. The described method, optimized by using Monte Carlo simulation, beam test and experimental data, allows the spectra to be measured up to 10TeV, thus extending the PAMELA observational range based on the magnetic spectrometer measurement.

Evaluation of the local hadronic calibration with combined beam-test data for the endcap and forward calorimeters of ATLAS in the pseudorapidity region [formula omitted

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.

Geant4 simulation of transition radiation detector based on DEPFET silicon pixel matrices

This paper presents new developments in Monte Carlo simulation for test beam measurements of a silicon transition radiation detector based on DEPFET—a silicon active pixel detector. The test of DEPFET with fiber radiator has been carried out at the DESY 5GeV electron beam. Monte Carlo simulation of the test beam setup is based on Geant4. A comparison of Geant4 simulation with test beam data is presented.

Performance of novel silicon n-in-p planar pixel sensors

The performance of novel n-in-p planar pixel detectors designed for future upgrades of the ATLAS Pixel system is presented. The n-in-p silicon sensors technology is a promising candidate for the pixel upgrade thanks to its radiation hardness and cost effectiveness that allow for enlarging the area instrumented with pixel detectors. The n-in-p modules presented here are composed of pixel sensors produced by CiS connected by bump-bonding to the ATLAS read-out chip FE-I3.The characterization of these devices has been performed before and after irradiation up to a fluence of 5×1015 1MeVneqcm−2. Charge collection measurements carried out with radioactive sources have proven the functioning of this technology up to these particle fluences. First results from beam test data with a 120GeV/c pion beam at the CERN-SPS are also discussed, demonstrating a high tracking efficiency of (98.6±0.3)% and a high collected charge of about 10ke for a device irradiated at the maximum fluence and biased at 1kV.

Performance of n-in-p Pixel Detectors Irradiated at Fluences up to 5x1015 neq/cm2 for the Future ATLAS Upgrades

Abstract We present the results of the characterization of novel n-in-p planar pixel detectors, designed for the future upgrades of the ATLAS pixel system. N-in-p silicon devices are a promising candidate to replace the n-in-n sensors thanks to their radiation hardness and cost effectiveness, that allow for enlarging the area instrumented with pixel detectors. The n-in-p modules presented here are composed of pixel sensors produced by CiS connected by bump-bonding to the ATLAS readout chip FE-I3. The characterization of these devices has been performed with the ATLAS pixel read-out systems, TurboDAQ and USBPIX, before and after irradiation with 25 MeV protons and neutrons up to a fluence of 5x10 15 neq/cm2. The charge collection measurements carried out with radioactive sources have proven the feasibility of employing this kind of detectors up to these particle fluences. The collected charge has been measured to be for any fluence in excess of twice the value of the FE-I3 threshold, tuned to 3200 e. The first results from beam test data with 120 GeV pions at the CERN-SPS are also presented, demonstrating a high tracking efficiency before irradiation and a high collected charge for a device irradiated at 10 15 neq/cm2. This work has been performed within the framework of the RD50 Collaboration.

Nature Frequency Identification of Prestressed Concrete Beam with RBF Network

Abstract. The relationship of pre-stressed concrete (PSC) beam natural frequency and pre-stressed force is difficult to described accurately with mechanical model. The past experimental data are collected. Then five unbonded post-tensioned PSC beams are designed. Frequencies and damps are collected in the dynamic experiment of five PSC beams. Radial basis function neural network is constructed to identify the natural frequencies of prestressed beam with different levels prestressing force based on previous test data and new dynamic test beam data. Then the input and output node numbers of neural network are selected and the appropriate training algorithm and expansion coefficient is determined. In order to verify that the network performance, one prestressed concrete beam test data are left to simulation test. Simulation results show that the radial basis function neural network is feasibility to recognize the frequency of PSC beams.

A study of hadronic shower development in the ECAL of the alpha magnetic spectrometer II

In this paper, we studied the development of hadronic shower in an electromagnetic calorimeter of Alpha Magnetic Spectrometer II. Two parametrized empirical formulae were proposed to describe the hadronic shower shape in calorimeter. Using 100 GeV proton beam incident on the center of the ECAL, detailed plots of lateral and longitudinal hadronic shower behavior were given and we found the formulae can describe the development of the hadronic shower with the test beam data. The possible application of the parametrized formulae including e±-π± discrimination and tau jet reconstruction was discussed.

Tests of a Particle Flow Algorithm with CALICE test beam data

The studies presented in this paper provide a first experimental test of the Particle Flow Algorithm (PFA) concept using data recorded in high granularity calorimeters. Pairs of overlaid pion showers from CALICE 2007 test beam data are reconstructed by the PandoraPFA program developed to implement PFA for a future lepton collider. Recovery of a neutral hadron's energy in the vicinity of a charged hadron is studied. The impact of the two overlapping hadron showers on energy resolution is investigated. The dependence of the confusion error on the distance between a 10 GeV neutral hadron and a charged pion is derived for pion energies of 10 and 30 GeV which are representative of a 100 GeV jet. The comparison of these test beam data results with Monte Carlo simulation is done for various hadron shower models within the GEANT4 framework. The results for simulated particles and for beam data are in good agreement thereby providing support for previous simulation studies of the power of Particle Flow Calorimetry at a future lepton collider.

Estimation of the material budget from tracker data to improve the quality of the track fit

We present two methods to improve the reconstruction of particle tracks by explicit estimates of the amount of material passed by the tracks. The first one is based on a linearized least-squares estimator, the second one on the combination of a forward and a backward Kalman filter. Our simulation studies show that it is possible to obtain a chi-square distribution that is indistinguishable from the one using the true material information. One of the methods has been validated using test beam data. Results of this validation are presented.

A layer correlation technique for pion energy calibration at the 2004 ATLAS Combined Beam Test

A new method for calibrating the hadron response of a segmented calorimeter is developed and successfully applied to beam test data. It is based on a principal component analysis of energy deposits in the calorimeter layers, exploiting longitudinal shower development information to improve the measured energy resolution. Corrections for invisible hadronic energy and energy lost in dead material in front of and between the calorimeters of the ATLAS experiment were calculated with simulated Geant4 Monte Carlo events and used to reconstruct the energy of pions impinging on the calorimeters during the 2004 Barrel Combined Beam Test at the CERN H8 area. For pion beams with energies between 20GeV and 180GeV, the particle energy is reconstructed within 3% and the energy resolution is improved by between 11% and 25% compared to the resolution at the electromagnetic scale.

Electrical Characterization and Preliminary Beam Test Results of 3D Silicon CMS Pixel Detectors

The fabrication of 3D detectors which requires bulk micromachining of columnar electrodes has been realized with advancements in MEMS technology. Since the fabrication of the first 3D prototype in Stanford Nanofabrication Facility in 1997, a significant effort has been put forth to transfer the 3D detector technology to large scale manufacturing for future high luminosity collider experiments, in which the radiation hardness will be the primary concern, and other applications such as medical imaging and X-ray imaging for molecular biology. First, alternative 3D structures, single type column (STC) and double-side double type column (DDTC) 3D detectors, were produced at FBK-irst (Trento, Italy) and CNM-Barcelona (Spain), and assessed thoroughly to improve the production technology towards the standard full-3D detectors. The 3D collaboration has been extended to include SINTEF (Norway), which is committed to small to medium scale production of active edge full-3D silicon sensors. This paper focuses on p-type 3D detectors compatible with the CMS pixel front end electronics from the second run of fabrication at SINTEF clean room facilities. The sensors that passed the wafer level electrical characterization have been bump-bonded at IZM (Germany), assembled into modules and wire-bonded for functional characterization at Purdue University. We report the leakage current characteristics, bump-bond quality, threshold, noise, and gain measurement results of these 3D modules as well as the preliminary beam test data taken at Fermi National Accelerator Laboratory.

PandoraPFA Tests using Overlaid Charged Pion Test Beam Data

The test beam data obtained with CALICE calorimeter prototypes were used to test the PandoraPFA program. The program capability to recover a neutral hadron energy in the vicinity of a charged hadron was studied. The impact of overlapping of two hadron showers on energy resolution was investigated. The dependence of the confusion error on the distance between a 10 GeV neutral hadron and a charged pion was derived for pion energies of 10 and 30 GeV which are representative of a 100 GeV jet. The comparison of these test beam data results with Monte Carlo simulation using GEANT4 physics lists was performed.

Tests of Local Hadron Calibration Approaches in ATLAS Combined Beam Tests

Three ATLAS calorimeters in the region of the forward crack at |η| = 3.2 in the nominal ATLAS setup and a typical section of the two barrel calorimeters at |η| = 0.45 of ATLAS have been exposed to combined beam tests with single electrons and pions. Detailed shower shape studies of electrons and pions with comparisons to various Geant4 based simulations utilizing different physics lists are presented for the endcap beam test. The local hadron calibration approach as used in the full Atlas setup has been applied to the endcap beam test data. An extension of it using layer correlations has been tested with the barrel test beam data. Both methods utilize modular correction steps based on shower shape variables to correct for invisible energy inside the reconstructed clusters in the calorimeters (compensation) and for lost energy deposits outside of the reconstructed clusters (dead material and out-of-cluster deposits). Results for both methods and comparisons to Monte Carlo simulations are presented.

Measurement of the neutron fraction event-by-event in DREAM

We have measured the neutron fraction event-by-event in beam test data taken at CERN by the DREAM collaboration. I will review these measurements in the context of the importance of neutrons to future high-precision calorimetry, and bring together the data from SPACAL, the GLD compensating calorimeter, and DREAM to estimate the impact neutron fraction measurements will make on hadronic energy resolution in dual-readout calorimeters.

Performance of the ATLAS Forward Calorimeters in First LHC Data

The ATLAS Forward Calorimeters (FCal) cover the very forward region of 3.1 < |η| < 4.9 and are hence designed to operate in a very high rate environment. This paper discusses the design of the FCal and presents studies of its performance in beam test data and LHC collision data. Measurements of the signal pulse shape, and the distribution of reconstructed cell energies are presented and compared with the expectation from simulations. A measurement of the location of the FCal is also performed in the data by studying the average deposited energy as a function of transverse distance to the beam axis.

Gflash as a Parameterized Calorimeter Simulation for the CMS Experiment

Gflash is a parameterized simulation of electromagnetic and hadronic showers. It uses parameterizations of longitudinal and lateral shower profiles in homogeneous or sampling calorimeters taking into account an individual shower fluctuation and correlation. Gflash can take over the Geant4 based tracking at the first inelastic interaction inside calorimeters. It can be tuned flexibly to data and speed up the calorimeter simulation significantly for high energy particle showers. In this paper, the Gflash implementation developed for the CMS calorimeter and tuned to the CMS test beam data is described. The performance of Gflash is also presented.

Z0 Boson measurement with the ALICE central barrel in pp collisions at 14TeV

The possibility to detect the Z0 in the ALICE central barrel is studied via the electronic decay channel Z0->e+e-. The signal and the background are simulated with the leading order event generator PYTHIA 6. The total cross-sections are taken from NLO calculations. Based on test beam data, the electron identification performance of the Transition Radiation Detector is extrapolated to high momenta. The expected yields for minimum-bias pp collisions at 14 TeV are presented. An isolation cut on the single electron, together with a minimum transverse momentum cut, allows to obtain a clear signal. The expected background is of the order of 1 % with the main contribution coming from misidentified pions from jets.

Results from first beam tests for the development of a RICH detector for CBM

In the CBM experiment at FAIR, electrons will be identified using a gaseous RICH detector positioned behind a system of silicon tracking stations. The concept of the RICH detector foresees an array of Multianode Photomultipliers (MAPMTs) as photodetector. First beam test data with a 2 GeV proton beam were recorded to investigate the Cherenkov light detection with a 64 channel Hamamatsu H8500 MAPMT. In the beam test a proximity focusing setup with a solid radiator was used together with a new self triggered readout electronics based on the n-XYTER ADC chip. The results of this beam test demonstrate that the new front end electronics is suited for the readout of the Hamamatsu H8500 MAPMT. It could be demonstrated that this MAPMT is able to detect single Cherenkov photons. Uncorrelated noise could be well separated from the signal using available timing information. The recorded number of MAPMT hits per beam event is consistent with the expectations.

Laser SEL Sensitivity Mapping of SRAM Cells

It is shown that laser sensitivity mapping at the cell level can be used to reconstruct and analyze the SEE cross-section. It resolves such conundrums as data pattern variations in the SEE sensitivity of memories. The pattern of SEE sensitivity revealed by the laser maps is shown to be reflected in features of ion beam test data.