Cosmic Ray Trigger Research Articles

Installation of a Cosmic-Ray Trigger System to Commission the Belle II Experiment VerteX Detector with Cosmic Rays

In this paper, we describe the design, construction, testing, and installation of the cosmic ray trigger system used to commission the VerteX Detector (VXD) of the Belle II experiment at the High-Energy Accelerator Research Organization (KEK) in Japan. The system consists of two rows of scintillators; with six scintillators being on top of the VXD, and six at the bottom of it. The scintillators were characterized (plateaus, threshold values, coincidences rate), and when compared with the simulation values a concordant match was found for all cosmic coincidence measurements. In Phase 3 of SuperKEKB accelerator, the VXD was the last sub-detector to be integrated into the heart of Belle II detector, after it was absent from being integrated within Belle II in Phase 1 and Phase 2 of SuperKEKB machine studies. A system consisting of VXD prototype parts had been installed, into Belle II detectors, at the VXD location during Phase 2 to study background and it was found that the VXD can cope with the level of measured background: allowing the VXD to be present during Phase 3 Belle II data taking. The VXD was tested with cosmic rays outside of Belle II before it was integrated within Belle II just before Phase 3 data taking, which commenced in March 2019.

Gated-Dynode photomultiplier tube assembly for the boronated scintillator detector of the ISS-CREAM experiment

Abstract We present the design of a four-photomultiplier tube (PMT) assembly for measuring light generation in the Boronated Scintillator Detector (BSD) of the Cosmic Ray Energetics And Mass experiment for the International Space Station (ISS-CREAM). The light produced in the scintillator includes a contribution from the capture of thermalized neutrons produced in cosmic ray interactions, as well as delayed fluorescence, in the range of several microseconds following the incident cosmic ray impact. The BSD is held in an insensitive state until a cosmic-ray trigger causes a rapid turn on of the PMTs to detect late light signals, several microseconds after the trigger. The design includes two pulsed high-voltage supplies, which serve to gate the first two dynodes of the Hamamatsu R1924A PMTs used in the assembly. When the dynode gates are held in the “off” state, this scheme is shown to suppress >10 5 photons from injection into the tube’s multiplier stage, while being capable of rapid switching into a stable operating mode in less than 1 μ s. This mitigates any backgrounds from afterpulsing that might otherwise be present in the PMT response following the cosmic ray incidence.

Realization of the Test System for the Trigger Logic in the DAMPE

As a part of the DAMPE (Dark Matter Particle Explorer), the trigger system is mainly used for discriminating the target particles (high-energy electrons and gamma-ray particles) from the non-target particles. The trigger system is mainly composed of the trigger detector and trigger logic circuits. This paper describes the design and implementation of the test system for the trigger logic of the DAMPE. Further more, we have designed and implemented also a cosmic ray trigger system, which is used to test the trigger efficiency of the DAMPE for muons. The testing method and the preliminary test result are given.

Analysis of cosmic-ray events with ALICE at LHC

ALICE is one of the four main experiments of the LHC at CERN. Located 40 meters underground, with 30 m of overburden rock, it can also operate to detect muons produced by cosmic-ray interactions in the atmosphere. An analysis of the data collected with cosmic-ray triggers from 2010 to 2013, corresponding to about 31 days of live time, is presented. Making use of the ability of the Time Projection Chamber (TPC) to track large numbers of charged particles, a special emphasis is given to the study of muon bundles, and in particular to events with high-muon density.

The prototype GAPS (pGAPS) experiment

The General Antiparticle Spectrometer (GAPS) experiment is a novel approach for the detection of cosmic ray antiparticles. A prototype GAPS (pGAPS) experiment was successfully flown on a high-altitude balloon in June of 2012. The goals of the pGAPS experiment were: to test the operation of lithium drifted silicon (Si(Li)) detectors at balloon altitudes, to validate the thermal model and cooling concept needed for engineering of a full-size GAPS instrument, and to characterize cosmic ray and X-ray backgrounds. The instrument was launched from the Japan Aerospace Exploration Agency's (JAXA) Taiki Aerospace Research Field in Hokkaido, Japan. The flight lasted a total of 6h, with over 3h at float altitude (~33km). Over one million cosmic ray triggers were recorded and all flight goals were met or exceeded.

Alignment of the ATLAS inner detector

In order to reach the track parameter accuracy motivated by the physics goals of the experiment, the ATLAS tracking system needs to determine accurately its almost 700,000 degrees of freedom. The demanded precision for the alignment of the silicon sensors is below 10 μm. The implementation of the track based alignment within the ATLAS software framework unifies different alignment approaches and allows the alignment of all tracking subsystems together. The alignment software relies on the tracking information (track-hit residuals) but also includes the capability to set constraints on the beam-spot and primary vertex as well as the momentum measured by the Muon System or the E/p using the calorimetry information. The alignment chain starts at the trigger level where a stream of high pT isolated tracks is selected online. Also a cosmic ray trigger is enabled while ATLAS is recording collision data, thus a stream of cosmic-ray tracks is recorded exactly with the same detector operating conditions as the normal collision tracks. We will present results of the alignment of the ATLAS tracker using the 2011 collision data. The validation of the alignment is performed using track-hit residuals as well as using more advanced physics observables. The results of the alignment with real data reveals that the attained precision for the alignment parameters is approximately 5 μm.

Performance of the ATLAS transition radiation tracker readout with high energy collisions at theLHC

The ATLAS Transition Radiation Tracker is the outermost of the three subsystems of the ATLAS Inner Detector. It contributes significantly to the precision of the momentum measurement of charged particles and to the identification of electrons. On the TRT front end electronics this is realized by discriminating the straw signal against two separate thresholds: a low one for tracking and a high one for electron identification. The electronics can also be configured to provide a trigger signal, which has been utilized to build a cosmic ray trigger that became extremely useful for the TRT as well as other subdetectors during ATLAS commissioning. This note will describe the TRT readout electronics and data acquisition, with emphasis on the experience gained during the first years of operation.

The integration of the ALICE trigger system with sub-detectors

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.

Bringing the ATLAS Muon Spectrometer to life with cosmic rays

The Muon Spectrometer of the ATLAS experiment at the Large Hadron Collider is the largest device ever built to track high energy particles. It has been designed to provide muon identification and measurement in the hard environment of proton–proton collisions at high energy and high luminosity at the LHC. An impressive number of elements, spread over the large volume of the spectrometer, were commissioned for many months with cosmic rays and were ready to take data when the first beam was circulated in the LHC. A systematic study of the detector's performance was done in the following months. More than 200 million cosmic ray triggers were taken in different conditions. We present the status of the muon detectors and the main results from the reconstruction of this event sample, showing that the ATLAS Muon Spectrometer is well advanced towards physics data taking.

Performance studies of the CMS Strip Tracker before installation

In March 2007 the assembly of the Silicon Strip Tracker was completed at the Tracker Integration Facility at CERN. Nearly 15% of the detector was instrumented using cables, fiber optics, power supplies, and electronics intended for the operation at the LHC. A local chiller was used to circulate the coolant for low temperature operation. In order to understand the efficiency and alignment of the strip tracker modules, a cosmic ray trigger was implemented. From March through July 4.5 million triggers were recorded. This period, referred to as the Sector Test, provided practical experience with the operation of the Tracker, especially safety, data acquisition, power, and cooling systems. This paper describes the performance of the strip system during the Sector Test, which consisted of five distinct periods defined by the coolant temperature. Significant emphasis is placed on comparisons between the data and results from Monte Carlo studies.

Track reconstruction of cosmic ray real data with the CMS Silicon Strip Tracker

The CMS tracking system consists of a silicon pixel vertex detector and a surrounding silicon microstrip detector. The system is currently going through final assembly stage. As the construction goes on, big parts of the detector are being powered, controlled and readout as a whole. A cosmic ray trigger has been setup, thus providing the first real events recorded in the CMS tracker. Reconstruction was performed with three track finder algorithms; we will talk about the Combinatorial Track Finder, which is based on the Kalman Filter technique for both trajectory building and track fitting. A dedicated algorithm for cosmic ray track's seeding has been developed, together with useful tools for the tracking performance analysis; the exercise has been very useful for the understanding and the improvement of the tracking algorithm.

Cosmic ray physics with ACORDE at LHC

The use of large underground high-energy physics experiments, for comic ray studies, have been used, in the past, at CERN, in order to measure, precisely, the inclusive cosmic ray flux in the energy range from 2·1010 ÷ 2· 1012 eV. ACORDE, ALICE Cosmic Rays DEtector, will act as Level 0 cosmic ray trigger and, together with other ALICE apparatus, will provide precise information on cosmic rays with primary energies around 1015 ÷ 1017 eV. This paper reviews the main detector features, the present status, commissioning and integration with other apparatus. Finally, we discuss the ACORDE-ALICE cosmic ray physics program.

ACORDE a cosmic ray detector for ALICE

ACORDE is one of the ALICE detectors, presently under construction at CERN. It consists of an array of plastic scintillator counters placed on the three upper faces of the ALICE magnet. It will act as a cosmic ray trigger, and, together with other ALICE sub-detectors, will provide precise information on cosmic rays with primary energies around 10 15 – 10 17 eV . Here we describe the design of ACORDE along with the present status and integration into ALICE.

A study of cosmic ray secondaries induced by the Mir space station using AMS-01

The Alpha Magnetic Spectrometer (AMS-02) is a high energy particle physics experiment that will study cosmic rays in the ∼100 MeV to 1 TeV range and will be installed on the International Space Station (ISS) for at least 3 years. A first version of AMS-02, AMS-01, flew aboard the space shuttle Discovery from June 2 to June 12, 1998, and collected 10 8 cosmic ray triggers. Part of the Mir space station was within the AMS-01 field of view during the four day Mir docking phase of this flight. We have reconstructed an image of this part of the Mir space station using secondary π − and μ − emissions from primary cosmic rays interacting with Mir. This is the first time this reconstruction was performed in AMS-01, and it is important for understanding potential backgrounds during the 3 year AMS-02 mission.

Measurement of TeV gamma-ray spectra with the Cherenkov imaging technique

In this paper, we seek to establish reliable methods for extracting energy spectra for TeV gamma-ray sources observed using the atmospheric Cherenkov Imaging Technique. Careful attention has been paid to the calculation of the telescope gain, and we obtain good agreement between direct measurements, with a statistical error of about 10%, and an absolute calibration from the background cosmic-ray trigger rate that has an overall error of 18%. Two independent analyses that are based on different Monte Carlo shower simulations, employ different selection criteria in order to retain a large fraction of gamma-ray events, and use different approaches to spectral estimation are presented here. The first is a fairly traditional method that builds on established image selection techniques and calculates the detector collection area and an energy estimation function. The error in measuring the enrgy of a single event is estimated at 36%, and we try to compensate for this poor energy resolution. The second analysis uses more elegant gamma-ray selection criteria and implicity incorporates the properties of the detector into the simulations that are then compared with the data in order to obtain source spectra. The two simulations are compared to each other and to the data, with the aim of establishing that each method is robust and insensitive to simulation details. Finally, we consider the main sources of systematic errors, the largest of which is in the telescope gain calibration, arising from an incomplete knowledge of the relevant factors, and is estimated to be 16%. The effect of possible errors in the simulations is also considered. Both methods have been applied to a part of the Whipple observatory database on the Crab Nebula for the 1988/89 observing season, while the first method has also been applied to data taken in 1995/96. The statistical error in the flux constant is about 8% and that in the spectral index is about 5%, while the corresponding systematic errors are estimated to be 18% and 2%, respectively. The results presented here show good agreement between the two methods as well as between the two seasons. However, a comprehensive consideration of the implications of the derived spectra and a comparison to other work is addressed in another paper.

Study of capillary tracking detectors with position-sensitive photomultiplier readout

Measurements have been carried out on light yield and attenuation length in glass capillaries filled with new liquid scintillators (LS) and compared with analogous measurements made on 0.5 mm diameter plastic fibres Kuraray SCSF-38 and 3HF. It is found that, at a distance of 1 m, the light output in the capillary filled with green LS based on 1-methylnaphthalene doped with a new dye 3M15 is greater by a factor of 2 to 3 than for plastic fibres. A tracking detector consisting of a capillary bundle read out by a 100 channel position-sensitive microchannel plate photomultiplier (2MCP-100) has been built and tested in the laboratory using a cosmic ray trigger. A comparison has been made between the performance of such a detector and that of a similar one, read out by a 96 channel Philips XP1724/A photomultiplier. It was found that a bundle made of 20 μm diameter capillaries with a tapered end giving a magnification of 2.56, filled with the new IPN+3M15 liquid scintillator, read out by the 2MCP-100, provides a space resolution of σ = 170 μm, a two-track resolution of the same value and a hit density of n = 1.9/mm for tracks crossing the detector at a distance of 20 cm from the photocathode. If the same detector is read out by the Philips XP1724/A, the space resolution becomes 200 μm, the two-track resolution 600 μm and the hit density n = 1.7/mm. The worse performance in the latter case is caused by the larger crosstalk compared with that of the 2MCP-100 PSPM. The results indicate that a LS-filled capillary detector is a very promising device for fast fibre tracking.

The digital data acquisition chain and the cosmic ray trigger system for the SLD warm iron calorimeter

The entire data acquisition chain, from the custom made front-end electronics to the Fastbus readout and data reduction module, for the digital readout of the SLD (see ref. [1]: SLD design report, SLAC-Report 73 (1984)) limited streamer tube Warm Iron Calorimeter and Muon Identifier is described. Also described is a Fastbus cosmic logic unit being developed to achieve the capability of reading cosmic ray events, also during the intercrossing time, for apparatus monitoring and calibration purposes.

Cosmic ray trigger circuit for large solenoidal particle detectors

We describe a circuit which electronically segments scintillation counters along their length in order to allow a selective trigger on cosmic ray muons of a given trajectory. This system is being used to provide a cosmic ray calibration and monitoring trigger for a large solenoidal spectrometer with several thousand wire chamber elements.

A flash tube chamber suitable for use at high repetition rates

Methods of reducing the recovery time of flash tubes by the addition of small amounts of molecular gas to the neon-helium gas mixture are described. The recovery time can be reduced from 300 ms for the tubes without additives to 0.6 ms for tubes at high pressure containing 2% of methane. The sensitive time is also reduced by the added gases, usually to times of a few microseconds, but further control of the sensitive time can be obtained by the application of alternating clearing fields. Apart from laboratory tests of the tubes using cosmic ray triggers, a flash tube chamber of 128 tubes, containing 30–70 neon-helium plus 1% methane, have been tested at rates up to 50 pulses per second in an electron beam. The digitized signals from the tubes were large enough to interface directly with a computerized Camac system. It was shown that the tubes had an internal efficiency of greater than 97% under these conditions and that they had no memory of previous events even at the highest rate tested.