Imaging of high-Z material for nuclear contraband detection with a minimal prototype of a Muon Tomography station based on GEM detectors

Muon Tomography based on the measurement of multiple scattering of atmospheric cosmic ray muons in matter is a promising technique for detecting heavily shielded high-Z radioactive materials (U, Pu) in cargo or vehicles. The technique uses the deflection of cosmic ray muons in matter to perform tomographic imaging of high-Z material inside a probed volume. A Muon Tomography Station (MTS) requires position-sensitive detectors with high spatial resolution for optimal tracking of incoming and outgoing cosmic ray muons. Micro Pattern Gaseous Detector (MPGD) technologies such as Gas Electron Multiplier (GEM) detectors are excellent candidates for this application. We have built and operated a minimal MTS prototype based on 30cm \times 30cm GEM detectors for probing targets with various Z values inside the MTS volume. We report the first successful detection and imaging of medium-Z and high-Z targets of small volumes (~0.03 liters) using GEM-based Muon Tomography

Event characterization of dark bosons via exotic Higgs decays with final states of displaced dimuons in high luminosity era of the LHC

We investigate the potential reach of a search for a long-lived/prompt dark vector boson $Z_D$, also called dark $Z$, and a prompt dark Higgs boson $h_D$ through exotic decays of the observed Higgs boson $h$ into either $Z_DZ_D$, $h_Dh_D$, or $ZZ_D$ with $Z$ being the hypercharge gauge boson. The $Z_D$ production through the Higgs portal is completed via one of two mechanisms, kinetic mixing of $Z_D$ with $Z$ and the mixing of $h_D$ with $h$. All production modes of $h$ are considered, while the branching fractions are calculated in Monte Carlo simulation using the {\textsc{MadGraph5}}\_aMC@NLO v2.7.2 framework. We focus on a final state of multiple dimuons, displaced up to \mbox{7500 mm}, where the muons can be reconstructed without vertex constraint using data from ATLAS and CMS detectors to be collected in Run~3. Integrated luminosities of 137, 300, and 3000 fb$^{-1}$ for Run~2, Run~3, and high luminosity run (HL-LHC), respectively, are used for estimating the expected search sensitivity of the Large Hadron Collider to each of the decay modes.Comment: 4 pages, 3 figures, ICHEP202

Performance of a Large-area GEM Detector Read Out with Wide Radial Zigzag Strips

A 1-meter-long trapezoidal Triple-GEM detector with wide readout strips was tested in hadron beams at the Fermilab Test Beam Facility in October 2013. The readout strips have a special zigzag geometry and run along the radial direction with an azimuthal pitch of 1.37 mrad to measure the azimuthal phi-coordinate of incident particles. The zigzag geometry of the readout reduces the required number of electronic channels by a factor of three compared to conventional straight readout strips while preserving good angular resolution. The average crosstalk between zigzag strips is measured to be an acceptable 5.5%. The detection efficiency of the detector is (98.4+-0.2)%. When the non-linearity of the zigzag-strip response is corrected with track information, the angular resolution is measured to be (193+-3) urad, which corresponds to 14% of the angular strip pitch. Multiple Coulomb scattering effects are fully taken into account in the data analysis with the help of a stand-alone Geant4 simulation that estimates interpolated track errors.Comment: 30 pages, 28 figures, submitted to NIM

Experimental Investigation of Hadron Collisions at the Highest Center-of-Mass Energies

In this report, we summarize the research in physics of elementary particles conducted by the Florida Tech DOE supported group at the CMS experiment at CERN, during the last 3-year cycle under this grant

Low-mass GEM detector with radial zigzag readout strips for forward tracking at the EIC

We present design and construction of a large low-mass Triple-GEM detector prototype for forward tracking at a future Electron-Ion Collider. In this environment, multiple scattering of forward and backward tracks must be minimized so that electron tracks can be cleanly matched to calorimeter clusters and so that hadron tracks can efficiently seed RICH ring reconstruction for particle identification. Consequently, the material budget for the forward tracking detectors is critical. The construction of the detector builds on the mechanical foil stretching and assembly technique pioneered by CMS for the muon endcap GEM upgrade. As an innovation, this detector implements drift and readout electrodes on thin large foils instead of on PCBs. These foils get stretched mechanically together with three GEM foils in a single stack. This reduces the radiation length of the total detector material in the active area by a factor seven from over 4% to below 0.6%. It also aims at improving the uniformity of drift and induction gap sizes across the detector and consequently signal response uniformity. Thin outer frames custom-made from carbon-fiber composite material take up the tension from the stretched foil stack and provide detector rigidity while keeping the detector mass low. The gas volume is closed with thin aluminized polyimide foils. The trapezoidal detector covers an azimuthal angle of 30.1 degrees and a radius from 8 cm to 90 cm. It is read out with radial zigzag strips with pitches of 1.37 mrad at the outer radius and 4.14 mrad at the inner radius that reduce the number of required electronics channels and associated cost while maintaining good spatial resolution. All front-end readout electronics is located away from the active area at the outer radius of the trapezoid.Comment: 4 pages, 7 figures, submitted to conference record of 2017 IEEE Nuclear Science Symposium, Atlanta, G

GEANT4 Simulation of a Cosmic Ray Muon Tomography System with Micro-Pattern Gas Detectors for the Detection of High-Z Materials

Muon Tomography (MT) based on the measurement of multiple scattering of atmospheric cosmic ray muons traversing shipping containers is a promising candidate for identifying threatening high-Z materials. Since position-sensitive detectors with high spatial resolution should be particularly suited for tracking muons in an MT application, we propose to use compact micro-pattern gas detectors, such as Gas Electron Multipliers (GEMs), for muon tomography. We present a detailed GEANT4 simulation of a GEM-based MT station for various scenarios of threat material detection. Cosmic ray muon tracks crossing the material are reconstructed with a Point-Of-Closest-Approach algorithm to form 3D tomographic images of the target material. We investigate acceptance, Z-discrimination capability, effects of placement of high-Z material and shielding materials inside the cargo, and detector resolution effects for such a MT station.Comment: 9 pages, 10 figures, submitted to conference proceedings of SORMA West 08, Berkele