Session KJ: Instrumentation - Tracking

Characterization and performance of the Silicon Vertex Tracker modules for the CLAS12 experiment

The Continuous Electron Beam Accelerator Facility's (CEBAF) Large Acceptance Spectrometer (CLAS) is being upgraded for the 12 GeV electron beam. The Silicon Vertex Tracker (SVT) will be part of the Central Tracker for the CLAS12 experiment and will be centered inside of the solenoid, which has 5 T magnetic field. We present the design, fabrication, characterization and performance of the SVT modules.   

Charged Track Reconstruction for GlueX at Jefferson Lab

The GlueX detector currently under construction at Jefferson Lab is a large acceptance device designed to facilitate the search for hybrid mesons. In order to accomplish this program, both photons and charged particles need to be reconstructed with high efficiency. Forward-going charged particles are detected in the Forward Drift Chambers while tracks exiting the target at angles greater than $\sim$20 degrees are detected in the Central Drift Chamber. Hits in both sets of detectors are associated into track segments that are linked together to form track candidates. These candidates are fit using the Kalman Filter formalism. The track reconstruction sequence from track finding through track fitting will be described. Single-track efficiencies and resolutions will be presented. Results for simulated events containing multiple charged particles relevant for the GlueX physics program will also be presented.   

Forward Drift Chamber for the GlueX experiment

The GlueX experiment will search for exotic mesons produced by 9 GeV linearly polarized photon beam from the 12 GeV CEBAF machine. A hermetic solenoid-based detector system that includes tracking and calorimetry is in the final construction phase. The Forward Drift Chamber consists of 24 circular planar drift chambers of $1~m$ diameter. Additional cathode strip information is required to achieve efficient pattern recognition in forward direction, resulting in 12,000 readout channels in total. Description and results from the tests of the completed detector will be presented. Challenges related to the specific features of the detector will be discussed. A small modification of the standard geometry allowed us to study the possibility for PID by cluster counting and investigate some gas properties based on single electron detection.   

A Drift Chamber to Measure Charged Particles at COMPASS-II

A new drift chamber (DC05) will be constructed to replace two tracking detector stations based on straw tubes, ST02 and ST03 in the COMPASS spectrometer. DC05 uses the designs from DC04, a previous drift chamber designed at CEA-Saclay, France, but adds the addition of more wires for improved acceptance. In addition to more wires DC05 will also change its front end electronics using a new pre-amplifier-discriminator chip (CMAD). DC05 consists of 8 layers of anode planes and 21 layers of G-10 material frames carrying cathode planes and gas windows. The wires are orientated with two layers in the vertical x-direction, two layers in the horizontal y-direction, two layers offset +10deg of the vertical x-direction, and two layers offset -10deg of the vertical x-direction. The wires in parallel directions are offset half a pitch to resolve left-right ambiguities. The purpose for different wire orientations is to reconstruct the 3D space particle trajectory to fit a particle track. Each layer of wires is covered on the top and bottom by a cathode plane of carbon coated mylar. All these layers are sandwiched between two steel stiffening frames for support and noise reduction. A future drift chamber, DC06, is also being designed based off of DC05.   

Drift Chamber Prototype for COMPASS-II Drell-Yan Measurements

The planned COMPASS-II experiment at CERN is poised to make the world's first measurement of the spin-dependent Drell-Yan (DY) process using a 190 GeV $\pi^-$ beam on a transversely polarized proton target. This program will provide a critical test of transverse momentum dependent processes including the first test of the prediction that the Sivers effect changes signs between SIDIS and DY. To enable these measurements two state-of-the-art large-area drift chambers, collectively known as DC56, are being developed for use in the existing COMPASS spectrometer. The DC56 design, based on the existing COMPASS DC04 drift chamber by CEA-Saclay, is optimized for large acceptance, stable operation, high efficiency in a high flux environment, and a 200 micron position resolution. This presentation will focus on a prototype $72\times16.5$in drift chamber with two planes of 16 sense wires at an 8mm pitch designed and built at the University of Illinois at Urbana-Champaign. The sense wires are alternated with field wires with an approximate 2kV potential difference. The wires are located between cathode planes made by depositing graphite on Mylar and Kapton. The performance of the prototype in cosmic ray tests and the status of the DC56 upgrades will be discussed.   

DESY Test-Beam Measurement with COMPASS Drift Chamber Prototypes

Two COMPASS drift chamber prototypes were tested at the DESY (Germany) test-beam facility in May 2013 to prepare a drift-chamber upgrade for COMPASS-II. A first small drift chamber prototype was designed and constructed at the University of Illinois at Urbana-Champaign. Its dimensions are 70cm x 30cm and it hosts one layer of eight sense wires. A second large drift chamber prototype was designed and constructed at CEA-Saclay, France. Its dimensions are 140cm x 35cm and it consists of two layers of each 16 sense wires. During a seven-day beam time, data from the two drift-chamber prototypes were collected in coincidence with six layers of a silicon beam telescope by impinging an electron beam with energies between 4 and 5 GeV onto the detector ensemble. The software framework EUTelescope was used to perform stand-alone track reconstruction from hits in the silicon layers. The drift chambers are read out with a pre-amplifier discriminator CMAD chip in combination with an FPGA-based TDC. They could be operated at excellent (satisfactory) noise level for the small (large) prototype with a charge threshold of 4fC (8fC). By synchronizing the two data streams from the drift chambers and the silicon detectors, the ``R-T-relation'' (distance information from the silicon data versus timing information from the drift chamber data) and the position resolution could be extracted. The preliminary analysis demonstrated that with the CMAD chip used, a drift-chamber position resolution of about 200um can be reached. The refined final results will be presented.   

Gas Electron Multiplier Detectors for TREK at J-PARC

Lepton flavor universality is a basic assumption of the Standard Model (SM). The proposed experiment E36 at J-PARC in Japan measures decay widths of stopped $K^{+}$ using the TREK (Time Reversal Experiment with Kaons) detector system to conduct precision measurements of $R_{K}=\Gamma(K^{+}\rightarrow e^{+}\nu)/\Gamma(K^{+}\rightarrow\mu^{+}\nu)$ in search of lepton flavor universality violation. The SM prediction for the ratio of leptonic $K^{+}$ decays is highly precise with an uncertainty of $\bigtriangleup R_{K} /R_{K} = 4\cdot10^{-4}$. Any observed deviation from the SM prediction would yield clear indication of New Physics beyond the Standard Model. To test lepton flavor universality violation a total uncertainty for the decay ratio of $K_{e2}/K_{\mu2}$ is aimed to be $0.25\%$ ($0.20\%$ stat$+ 0.15\%$ sys). The second portion of the experiment searches for heavy sterile neutrinos (N) in the $K^{+}\rightarrow\mu^{+}N$ decay and allows for further stringent searches for light new particles as a byproduct. Gas Electron Multiplier (GEM) detectors will be constructed for this experiment in order to measure charged tracks of $\mu^{+}$ and $e^{+}$ from charged $K^{+}$ decay. I will present Geant4 simulations of the TREK setup augmented with the GEM detectors.   

Performance of the Newly Commissioned PHENIX Triggering Resistive Plate Chambers During RHIC RUN 13

Determining the contributions of the sea quarks and other partons to the spin structure of the proton is important to our understanding of QCD. Collisions of longitudinally polarized protons at high energies provide a measurement of the flavor dependent contributions. In particular, the production of W-bosons at forward rapidity is sensitive to the flavor dependent spin contributions. The PHENIX detector at RHIC is well designed to make this measurement but required an upgrade to the forward trigger. The new PHENIX Muon Trigger has enabled the selection of W-bosons events that can be detected through the appearance of a high-energy muon in one of the two existing muon spectrometers. The trigger upgrade is based on new front-end electronics for the muon tracking chambers and the addition of two stations of Resistive Plate Chambers in both muon arms. The performance of these new stations of RPCs during the just completed successful RHIC run has been studied and will be presented.   

Studies for a Micro Vertex System in a EIC Detector using Monolithic Active Pixel Sensors

More than thirty years after Quantum Chromo-Dynamics (QCD) was first proposed as the fundamental theory of the strong force, very little is still known about the dynamical basis of the hadron structure. We still don't know completely where fundamental quantities of the nucleons like spin came from or what is the space distribution of gluons in nucleons. To investigate these fundamental questions a new Electron Proton/Ion Collider (eRHIC) is proposed to be built at Brookhaven National Laboratory. The inner tracking system of the detector in this collider will require very high granularity, very low material budget, hermetic coverage and a radiation hard design. For this detector it will be crucial to identify tracks of charged low momentum leptons at high rapidities. In this talk, an overview will be given on the eRHIC collider project at BNL, on the present design of the eRHIC detector. Further it will be shown that Monolithic Active Pixel Sensor (MAPS) realized with CMOS technology satisfy all these requirements and first test results of these sensors will be provided.