Test Beam Experiment Research Articles

The simulation of the CMS electromagnetic calorimeter

The CMS Collaboration has developed a detailed simulation of the electromagnetic calorimeter (ECAL), which has been fully integrated in the collaboration software framework CMSSW. The simulation is based on the Geant4 detector simulation toolkit for the modelling of the passage of particles through matter and magnetic field. The geometrical description of the detector is being re-implemented using the DetectorDescription language, combining an XML based description with the algorithmic definition of the position of the elements. The ECAL simulation software is fully operational and has been validated using real data from the ECAL test beam experiment that took place in summer 2006.

Data acquisition in the EUDET project

The goal of the EUDET project is the development and construction of infrastructure to permit detector R&D for the international linear collider (ILC) with larger scale prototypes. It encompasses major detector components: the vertex detector, the tracker and the calorimeters. We describe here the status and plans of the project with emphasis on issues related to data acquisition for future test beam experiments.

Electron signals in the Forward Calorimeter prototype for ATLAS

A pre-production prototype of the Forward Calorimeter (FCal) for the ATLAS detector presently under construction at the Large Hadron Collider (LHC) at CERN, Geneva, Switzerland, was exposed to electrons in the momentum range from 20 to 200 GeV/c in a test beam experiment at CERN in 1998. The measured performance, including a signal linearity within about ±1% and a high energy limit in the relative energy resolution of about 4%, meets the expectations for this kind of calorimeter, and exceeds the physics requirements for successful application in ATLAS.

Study of a proximity focusing RICH with a silica aerogel radiator

A proximity focusing RICH based on a silica aerogel Cherenkov radiator has been developed for a new particle identification device in the upgraded Belle detector. To further improve the detector performance, a new concept for Cherenkov ring imaging has been introduced, where multiple aerogel layers with different indices are accumulated to increase the number of detected photons without making the Cherenkov photon angle resolution worse. By constructing a prototype counter, this idea was validated in a test beam experiment, and a 5.5 σ π / K separation at 4 GeV / c with more than nine photoelectrons was achieved. We will present new results from a beam test as well as recent improvements on aerogel radiators.

A study of proximity focusing RICH with aerogel radiator

Proximity focusing RICH based on an aerogel Cherenkov radiator has been developed for a new particle identifier in the Belle upgrade. To further improve the detector performance, a new concept for Cherenkov ring imaging has been introduced, where multiple aerogel layers with different indices are accumulated to increase observed photoelectrons without making the single photon resolution worse. By constructing a prototype counter, this idea was validated in a test beam experiment, and we achieved 5.5 σ π / K separation at 4 GeV / c . In addition, the potential of the time-of-flight capabilities to detect time information of Cherenkov photons, where a micro-channel plate PMT is employed as a photodetector, was examined in a beam test, and excellent performance of this technique was obtained.

Hadron beam test of a scintillating fibre tracker system for elastic scattering and luminosity measurement in ATLAS

A scintillating fibre tracker is proposed to measure elastic proton scattering at very small angles in the ATLAS experiment at CERN. The tracker will be located in so-called Roman Pot units at a distance of 240 m on each side of the ATLAS interaction point. An initial validation of the design choices was achieved in a beam test at DESY in a relatively low energy electron beam and using slow off-the-shelf electronics.Here we report on the results from a second beam test experiment carried out at CERN, where new detector prototypes were tested in a high energy hadron beam, using the first version of the custom designed front-end electronics. With a spatial resolution of 25 μm an adequate tracking performance was obtained, under conditions which are similar to the situation at the LHC.In addition, the alignment method using so-called overlap detectors was studied and shown to have the expected precision.

The CMS silicon strip tracker

With more than 15,000 silicon strip modules and an active silicon area of 200 m 2, the Compact Muon Solenoid silicon strip tracker will be the largest silicon tracker ever built. While module mass production has started in 2004, the detector construction has recently entered its crucial phase with modules being assembled onto larger substructures, which in turn are being integrated into the tracker barrel and end-cap structures. In this presentation the detector design will be introduced. The challenges and experiences of the silicon module mass production, with focus on the key components such as sensors and hybrids, will be presented. The status of the integration of modules onto the detector substructures, as well as the construction and integration of the large barrel and end-cap structures will be described. Finally, an overview will be given on the excellent performance of subsystems of the tracker as demonstrated by system tests and test beam experiments.

The CMS silicon strip end cap tracker: Overview and status

While module mass production has started in 2004, the detector construction has entered its hot phase this Spring. The silicon modules are assembled onto substructures, which in turn are integrated into the end cap structures. The detector design, the challenges and experiences of a silicon module mass production of unprecedented scale, the status of the integration of modules onto the detector substructures are introduced as well as the construction and integration of the end cap structures. The excellent performance of the substructures as observed in system tests and test beam experiments are presented.

Luminosity measurement at ATLAS—Development, construction and test of scintillating fibre prototype detectors

We are reporting about a scintillating fibre tracking detector which is proposed for the precise determination of the absolute luminosity of the CERN LHC at interaction point 1 where the ATLAS experiment is located. The detector needs to track protons elastically scattered under μ rad angles in direct vicinity to the LHC beam. It is based on square shaped scintillating plastic fibres read out by multi-anode photomultiplier tubes and is housed in Roman Pots. We describe the design and construction of prototype detectors and the results of a beam test experiment at DESY. The excellent detector performance established in this test validates the detector design and supports the feasibility of the proposed challenging method of luminosity measurement.

Undulator background in the final focus test beam experiment with polarized positrons

In the proposed E-166 experiment at SLAC, 50 GeV electrons pass through a helical undulator, and produce circularly polarized photons, which interact with a tungsten target and generate longitudinally polarized positrons. The background is an important issue for an experiment under consideration. To address this issue, simulations were performed with the code GEANT3 to model the production of secondary particles from high-energy electrons hitting an undulator. The energy density of photons generated at the target has been analyzed. Results of the simulations are presented and discussed.

The LHCb Silicon Tracker Project

Two silicon strip detectors, the Trigger Tracker(TT) and the Inner Tracker(IT) will be constructed for the LHCb experiment. Transverse momentum information extracted from the TT will be used in the Level 1 trigger. The IT is part of the main tracking system behind the magnet. Both silicon detectors will be read out using a custom-developed chip by the ASIC lab in Heidelberg. The signal-over-noise behavior and performance of various geometrical designs of the silicon sensors, in conjunction with the Beetle read-out chip, have been extensively studied in test beam experiments. Results from those experiments are presented, and have been used in the final choice of sensor geometry.

Coherent radio pulses from GEANT generated electromagnetic showers in ice

Radio Cherenkov radiation is arguably the most efficient mechanism for detecting showers from ultrahigh energy particles of 1 PeV and above. Showers occurring in Antarctic ice should be detectable at distances up to 1 km. We report on electromagnetic shower development in ice using a GEANT Monte Carlo simulation. We have studied energy deposition by shower particles and determined shower parameters for several different media, finding agreement with published results where available. We also report on radio pulse emission from the charged particles in the shower, focusing on coherent emission at the Cherenkov angle. Previous work has focused on frequencies in the 100 MHz to 1 GHz range. Surprisingly, we find that the coherence regime extends up to tens of GHz. This may have substantial impact on future radio-based neutrino detection experiments as well as any test beam experiment which seeks to measure coherent Cherenkov radiation from an electromagnetic shower. Our study is particularly important for the RICE experiment at the South Pole.

Compatibilization of poly(vinyl chloride) and polyolefin elastomer blends with multiblock/blocky chlorinated polyethylenes

Asymmetric double cantilever beam and peel test experiments were completed to evaluate the ability of chlorinated polyethylenes to compatibilize poly(vinyl chloride) (PVC) and polyolefin elastomer (POE) blends. A series of chlorinated polyethylenes that are blocky in nature (bCPEs) with varying composition (% chlorine) and molecular weight (melt index) were compared to one chlorinated polyethylene, where the chlorine is randomly distributed throughout the chain (rCPE). Results indicate that improvement in the interfacial adhesion between the PVC and the POE is dramatically more pronounced with the bCPEs than with the rCPE. In addition, the optimum bCPE composition was determined to be 20% chlorine and the interfacial adhesion force was found to increase with increasing molecular weight. Finally, the POE/CPE interaction was found to govern the ability of the chlorinated polyethylene to compatibilize PVC and POE.

Backsplash studies for the Scintillator Pad Detector of LHCb in a tagged-photon test beam

The Scintillator Pad Detector (SPD) of the LHCb experiment is part of the calorimeter system, positioned just before the preshower (PS), and is meant to separate photons and electrons at level 0 of the trigger. A tagged-photon test beam allowed to test in photon signals the SPD. These signals are mainly due to pair production inside the scintillator and to particles generated in the electromagnetic shower in the PS and in the electromagnetic calorimeter (backsplash). The observed results in a test beam experiment stress the low inefficiencies in e/γ separation arising from backsplash.

Results for electrons from the 1995 ATLAS forward calorimeter prototype testbeam

The performance of the ATLAS electromagnetic liquid argon/brass forward calorimeter with its new readout geometry consisting of tube/rod electrodes with cylindrical shell gaps, has been evaluated with a full depth prototype in a testbeam experiment with electrons in 1995. The results for signal linearity of better than 1% and a constant term in the relative energy resolution of 3% meet and even exceed the original performance requirements very well. Space resolution in the order of 0.5 mm in the high energy limit, and an insignificant signal dependency on the electron impact angle have been found in addition.

Performance of a GaAs microstrip detector in a test beam experiment

A commercially produced gallium arsenide microstrip detector has been tested in a 100 GeV electron/pion beam. The detector has a 50 μm pitch on a 200 μm thick substrate. The signal-to-noise ratio was 13-to-1 at the maximum voltage of 180 V and the detection efficiency was better than 99%. The charge-collection efficiency was estimated to be 41% corresponding to a collected charge of 10 600e. The spatial resolution was found to approach the expectation of ≈ pitch S N . There is some evidence for an unusual charge sharing which may be due to trapping.

Test beam results using scintillating fibers read out by a multianode phototube and visible light photon counters

The results from a test beam experiment at Fermilab using 830 μm scintillating fibers, a version of a solid state photomultiplier, the VLPC, and a 256 channel multianode phototube are reported. Muon tracks were observed in a combined tracking system read out by VLPCs and the multianode phototube. A tracking algorithm was developed to unfold the complex cross talk pattern observed in the multianode phototube. A spatial resolution of ∼ 130 μm was obtained.

Author index to volumes A321–A330 subject index to volumes A321–A330

The results from a test beam experiment at Fermilab using 830 μm scintillating fibers, a version of a solid state photomultiplier, the VLPC, and a 256 channel multianode phototube are reported. Muon tracks were observed in a combined tracking system read out by VLPCs and the multianode phototube. A tracking algorithm was developed to unfold the complex cross talk pattern observed in the multianode phototube. A spatial resolution of ∼ 130 μm was obtained.

Version 2 of RSXMULTI

MULTI is a general purpose, high speed, high energy physics interface to data acquisition and data investigation system that runs on PDP-11 and VAX architecture. This paper describes the latest version of MULTI, which runs under RSX-11M version 4.1 and supports a modular approach to the separate tasks that interface to it, allowing the same system to be used in single CPU test beam experiments as well as multiple interconnected CPU, large scale experiments. MULTI uses CAMAC (IEE-583) for control and monitoring of an experiment, and is written in FORTRAN-77 and assembler. The design of this version, which simplified the interface between tasks, and eliminated the need for a hard to maintain homegrown I/O system is also discussed.