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    Construction and Testing of Novel Designs of Resistive Plate Chambers
    (IEEE, 2018) Bilki, Burak; Onel, Yasar; Repond, Jose; Xia, Lei
    Resistive Plate Chambers (RPCs) exhibit a significant loss of efficiency for the detection of particles, when subjected to high particle fluxes. This rate limitation is related to the usually high resistivity of the resistive plates used in their construction. Here we report on the measurements of the performance of various different glass RPC designs featuring a different total resistance of the resistive plates. In parallel, a novel design of RPC, using only a single resistive plate, was developed and tested. Based on this design, large size prototype chambers were constructed and were tested with cosmic rays and in particle beams. The tests confirmed the viability of this new approach.
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    Design, Construction and Commissioning of the Upgrade Radiation Damage Monitoring System of the CMS Hadron Forward Calorimeters
    (IEEE, 2018) Bilki, Burak; Onel, Yasar
    The CMS Hadron Forward Calorimeters cover pseudorapidities between 3.0 and 5.0 being exposed to the highest radiation levels in the CMS detector system. The calorimeter consists of quartz fibers as active media inserted into the steel absorber structure. The radiation damage of the quartz fibers is monitored using dedicated data taking by measuring the fraction of laser light intensity after traversing the quartz fibers. Recently, a new monitoring device based on solid state laser diode technology was designed, constructed and installed. The basic operational integrity was tested extensively prior to installation. The module was integrated into the front-end electronics in a similar way as the Phase I Upgrade LED calibration system. Here we describe the details of the radiation monitoring system and present the commissioning and integration phases.
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    New Radiation-Hard Wavelength Shifting Fibers
    (IEEE, 2016) Bilki, Burak; Onel, Yasar; Tiras, Emrah; Wetzel, James; Winn, David
    R&D on new radiation-hard wavelength shifting fibers is gaining crucial importance as the radiation conditions projected for the High Luminosity LHC and future hadron and lepton colliders reach unprecedented levels. We have identified materials with proven radiation resistance, long Stokes shifts to enable long self-absorption lengths, with decay constants similar to 10 ns or less. Here we describe two strong candidates' Doped ZnO:Zn/Mg and 3HF (3-hydroxyflavone) properties along with other material options and report on basic performance characteristics of recent prototypes.
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    Operational Experience with the CMS Hadron Forward Calorimeters Phase I Upgrade
    (IEEE, 2018) Bilki, Burak; Onel, Yasar; Gulmez, Erhan
    The Phase I Upgrade of the CMS Hadron Forward Calorimeters was completed during the Extended Year End Technical Stop of 2016 - 2017. In the framework of the upgrade, the front-end electronics were replaced and the PMT boxes were reworked to implement two-channel readout in order to exploit the benefits of the multi-anode PMTs. The new PMTs with two channel readout allow background tagging and signal recovery. In addition, the front-end electronics implement a 6-bit TDC to provide an additional handle to eliminate the background. The Hadron Forward Calorimeters were commissioned and operated successfully in 2017 data taking period. Here we describe the details and the components of the upgrade, and discuss the operational experience with the Phase I Upgrade.
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    Radiation Damage Studies of New Intrinsically Radiation-Hard Scintillators
    (IEEE, 2016) Bilki, Burak; Onel, Yasar; Tiras, Emrah; Wetzel, James; Winn, David
    Following the development of intrinsically radiation-hard scintillators, we exposed various scintillators tiles to gammas from a Cs-137 source at the University of Iowa Hospitals and Clinics up to 1.4 and 14 Mrad. The results are within expectations and exhibit sufficiently high performance for implementations in the future/upgrade hadron/lepton collider detectors. Here we report on the nature of the irradiation tests and present the results of the laboratory measurements performed continuously for more than 60 days following the irradiation under various recovery conditions.