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FNAL-NICADD extruded scintillator

Description: The possibility to produce a scintillator that satisfies the demands of physicists from different science areas has emerged with the installation of an extrusion line at Fermi National Accelerator Laboratory (FNAL). The extruder is the product of the fruitful collaboration between FNAL and Northern Illinois Center for Accelerator and Detector Development (NICADD) at Northern Illinois University (NIU). The results from the light output, light attenuation length and mechanical tolerance indicate that FNAL-NICADD scintillator is of high quality. Improvements in the extrusion die will yield better scintillator profiles and decrease the time needed for initial tuning. This paper will present the characteristics of the FNAL-NICADD scintillator based on the measurements performed. They include the response to MIPs from cosmic rays for individual extruded strips and irradiation studies where extruded samples were irradiated up to 1 Mrad. We will also discuss the results achieved with a new die design. The attractive perspective of using the extruded scintillator with MRS (Metal Resistive Semiconductor) photodetector readout will also be shown.
Date: September 1, 2005
Creator: Beznosko, D.; U., /Northern Illinois; Bross, A.; /Fermilab; Dyshkant, A.; U., /Northern Illinois et al.
Partner: UNT Libraries Government Documents Department

Search for Leptoquarks with the D0 detector

Description: We report on D0 searches for leptoquarks (LQ) predicted in extended gauge theories and composite models to explain the symmetry between quarks and leptons. Data samples obtained with the D0 detector from p{bar p} collisions at a center-of-mass energy of 1.96 TeV corresponding to integrated luminosities of 1-4 fb{sup -1} were analyzed. No evidence for the production of such particles were observed and lower limits on leptoquark masses are set.
Date: October 1, 2009
Creator: Uzunyan, Sergey A. & U., /Northern Illinois
Partner: UNT Libraries Government Documents Department

A search for charge 1/3 third generation leptoquarks in muon channels

Description: Leptoquarks are exotic particles that have color, electric charge, and lepton number and appear in extended gauge theories and composite models. Current theory suggests that leptoquarks would come in three different generations corresponding to the three quark and lepton generations. We are searching for charge 1/3 third generation leptoquarks produced in p{bar p} collisions at {radical}s = 1.96 TeV using data collected by the D0 detector. Such leptoquarks would decay into either a tau-neutrino plus a b-quark or, if heavy enough, to a tau-lepton plus a t-quark. We present preliminary results on an analysis where both leptoquarks decay into neutrinos giving a final state with missing energy and two b-quarks using 367 pb{sup -1} of Run II D0 data taken between August 2002 and September 2004. We place upper limits on {sigma}(p{bar p} {yields} LQ{ovr LQ})B{sup 2} as a function of the leptoquark mass M{sub LQ}. Assuming B = 1, we exclude at the 95% confidence level third generation leptoquarks with M{sub LQ} < 197 GeV/c{sup 2}.
Date: August 1, 2006
Creator: Uzunyan, Sergey A. & U., /Northern Illinois
Partner: UNT Libraries Government Documents Department

A search for third generation scalar leptoquarks

Description: Leptoquarks (LQ) are particles with both color and lepton number predicted in some gauge theories and composite models. Current theory suggests that leptoquarks would come in three different generations. We report on a search for charge 1/3 third generation leptoquarks produced in p{bar p} collisions at {radical}s = 1.96 TeV using data collected by the D0 detector at Fermilab. Such leptoquarks would decay into a tau-neutrino plus a b-quark with branching fraction B. We present preliminary results on an analysis where both leptoquarks decay into neutrinos giving a final state with missing energy and two b-jets. Using 425(recorded) pb{sup -1} of data, we place limits on {sigma}(p{bar p} {yields} LQ{ovr LQ})B{sup 2} as a function of the leptoquark mass. Assuming B = 1, we excluded at the 95% confidence level scalar third generation leptoquarks with M{sub LQ} < 219 GeV.
Date: August 1, 2006
Creator: Zatserklyaniy, Andriy & U., /Northern Illinois
Partner: UNT Libraries Government Documents Department

A quantitative study of a physics-first pilot program

Description: Hundreds of high schools around the United States have inverted the traditional core sequence of high school science courses, putting physics first, followed by chemistry, and then biology. A quarter-century of theory, opinion, and anecdote are available, but the literature lacks empirical evidence of the effects of the program. The current study was designed to investigate the effects of the program on science achievement gain, growth in attitude toward science, and growth in understanding of the nature of scientific knowledge. One hundred eighty-five honor students participated in this quasi-experiment, self-selecting into either the traditional or inverted sequence. Students took the Explore test as freshmen, and the Plan test as sophomores. Gain scores were calculated for the composite scores and for the science and mathematics subscale scores. A two-factor analysis of variance (ANOVA) on course sequence and cohort showed significantly greater composite score gains by students taking the inverted sequence. Participants were administered surveys measuring attitude toward science and understanding of the nature of scientific knowledge twice per year. A multilevel growth model, compared across program groups, did not show any significant effect of the inverted sequence on either attitude or understanding of the nature of scientific knowledge. The sole significant parameter showed a decline in student attitude independent of course sequence toward science over the first two years of high school. The results of this study support the theory that moving physics to the front of the science sequence can improve achievement. The importance of the composite gain score on tests vertically aligned with the high-stakes ACT is discussed, and several ideas for extensions of the current study are offered.
Date: September 1, 2008
Creator: Pasero, Spencer Lee & U., /Northern Illinois
Partner: UNT Libraries Government Documents Department

Measurement of sigma(p anti-p -> t anti-t) in the tau + jets channel by the D� experiment at Run II of the Tevatron Collider

Description: The top quark is the heaviest and most mysterious of the known elementary particles. Therefore, careful study of its production rate and other properties is of utmost importance for modern particle physics. The Tevatron is the only facility currently capable of studying top quark properties by on-shell production. Measurement of the top quark pair production cross section is one of the major goals of the Tevatron Run II physics program. It provides an excellent test of QCD at energies exceeding 100 GeV. We report on a new measurement of p{bar p} {yields} t{bar t} production at {radical} = 1.96 TeV using 350 pb{sup -1} of data collected with the D0 detector between 2002 and 2005. We focus on the final state where a W boson from one of the top quarks decays into a {tau} lepton and its associated neutrino, while the other decays into a quark-antiquark pair. We aim to select those events in which the {tau} lepton subsequently decays to one or three charged hadrons, zero or more neutral hadrons and a tau neutrino (the charge conjugate processes are implied in all of the above). The observable signature thus consists of a narrow calorimeter shower with associated track(s) characteristic of a hadronic tau decay, four or more jets, of which two are initiated by b quarks accompanying the W's in the top quark decays, and a large net missing momentum in the transverse plane due to the energetic neutrino-antineutrino pair that leave no trace in the detector media. The preliminary result for the measured cross section is: {sigma}(t{bar t}) = 5.1{sub -3.5}{sup +4.3}(stat){sub -0.7}{sup +0.7}(syst) {+-} 0.3 (lumi.) pb.
Date: July 1, 2008
Creator: Arov, Mikhail & U., /Northern Illinois
Partner: UNT Libraries Government Documents Department

Search for Squarks and Gluinos with the D0 detector

Description: We report on D0 searches for scalar quarks ({tilde q}) and gluinos ({tilde g}), the superpartners of quark and gluons, in topologies involving jets and missing transverse energies. Data samples obtained with D0 detector from p{bar p} collisions at a center-of-mass energy of 1.96 TeV corresponding to an integrated luminosities of 1-4 fb{sup -1} were analyzed. No evidence for the production of such particles were observed and lower limits on squarks and gluino masses were set.
Date: October 1, 2009
Creator: Uzunyan, Sergey A. & U., /Northern Illinois
Partner: UNT Libraries Government Documents Department

Physics validation studies for muon collider detector background simulations

Description: Within the broad discipline of physics, the study of the fundamental forces of nature and the most basic constituents of the universe belongs to the field of particle physics. While frequently referred to as 'high-energy physics,' or by the acronym 'HEP,' particle physics is not driven just by the quest for ever-greater energies in particle accelerators. Rather, particle physics is seen as having three distinct areas of focus: the cosmic, intensity, and energy frontiers. These three frontiers all provide different, but complementary, views of the basic building blocks of the universe. Currently, the energy frontier is the realm of hadron colliders like the Tevatron at Fermi National Accelerator Laboratory (Fermilab) or the Large Hadron Collider (LHC) at CERN. While the LHC is expected to be adequate for explorations up to 14 TeV for the next decade, the long development lead time for modern colliders necessitates research and development efforts in the present for the next generation of colliders. This paper focuses on one such next-generation machine: a muon collider. Specifically, this paper focuses on Monte Carlo simulations of beam-induced backgrounds vis-a-vis detector region contamination. Initial validation studies of a few muon collider physics background processes using G4beamline have been undertaken and results presented. While these investigations have revealed a number of hurdles to getting G4beamline up to the level of more established simulation suites, such as MARS, the close communication between us, as users, and the G4beamline developer, Tom Roberts, has allowed for rapid implementation of user-desired features. The main example of user-desired feature implementation, as it applies to this project, is Bethe-Heitler muon production. Regarding the neutron interaction issues, we continue to study the specifics of how GEANT4 implements nuclear interactions. The GEANT4 collaboration has been contacted regarding the minor discrepancies in the neutron interaction cross sections for boron. ...
Date: July 1, 2011
Creator: Morris, Aaron Owen & U., /Northern Illinois
Partner: UNT Libraries Government Documents Department

Effects of the 9-T magnetic field on MRS photodiode

Description: The experimental results on the performance of the MRS (Metal/Resistor/Semiconductor) photodiode in the strong magnetic field of 9T, and the possible impact of the quench of the magnet at 9.5T on sensor's operation are reported. The measurement method used is being described. The results of the work agree with the expectations that the MRS photodiode is not exhibiting sensitivity to the magnetic field presence. This result is essential for the design of the future electron-positron linear collider detector.
Date: October 1, 2005
Creator: Beznosko, D.; Blazey, G.; Dyshkant, A.; Rykalin, V. & U., /Northern Illinois
Partner: UNT Libraries Government Documents Department

Silicon photomultiplier choice for the scintillating fibre tracker in second generation proton computed tomography scanner

Description: Scintillating fibers are capable of charged particle tracking with high position resolution, as demonstrated by the central fiber tracker of the D0 experiment. The charged particles will deposit less energy in the polystyrene scintillating fibers as opposed to a typical silicon tracker of the same thickness, while SiPM's are highly efficient at detecting photons created by the passage of the charged particle through the fibers. The current prototype of the Proton Computed Tomography (pCT) tracker uses groups of three 0.5 mm green polystyrene based scintillating fibers connected to a single SiPM, while first generation prototype tracker used Silicon strip detectors. The results of R&D for the Scintillating Fiber Tracker (SFT) as part of the pCT detector are outlined, and the premise for the selection of SiPM is discussed.
Date: March 1, 2012
Creator: Gearhart, A.; Johnson, E.; Medvedev, V.; U., /Northern Illinois; Ronzhin, A.; /Fermilab et al.
Partner: UNT Libraries Government Documents Department

Modular design of long narrow scintillating cells for ILC detector

Description: The experimental results for the narrow scintillating elements with effective area about 20 cm{sup 2} are reported. The elements were formed from the single piece of scintillator and were read out via wavelength shifting fibers with the MRS (Metal/Resistor/Semiconductor) photodiodes on both ends of each fiber. The formation of the cells from the piece of scintillator by using grooves is discussed. The cell performance was tested using the radioactive source by measuring the PMT current and a single rate after amplifier and discrimination with threshold at about three photo electrons in each channel and quad coincidences (double coincidences between sensors on each fiber and double coincidences between two neighboring fibers). This result is of high importance for large multi-channel systems, i.e. module may be used as an active element for calorimeter or muon system for the design of the future electron-positron linear collider detector because cell effective area can be smoothly enlarged or reduced (to 4 cm{sup 2} definitely).
Date: September 1, 2005
Creator: Beznosko, D.; Blazey, G.; Dyshkant, A.; Maloney, J.; Rykalin, V.; U., /Northern Illinois et al.
Partner: UNT Libraries Government Documents Department

Longitudinal electron bunch diagnostics using coherent transition radiation

Description: The longitudinal charge distribution of electron bunches in the Fermilab/Nicadd A0 photoinjector was determined using the coherent transition radiation produced by electrons passing through a thin metallic foil. The autocorrelation of the transition radiation signal was measured with a Michelson-type interferometer. The response function of the interferometer was determined from measured and simulated power spectra for low electron bunch charge and maximum longitudinal compression. A Kramers-Kronig technique was used to determine longitudinal charge distribution. Measurements were performed for electron bunch lengths in the range from 0.3 to 2 ps (rms).
Date: May 1, 2005
Creator: Mihalcea, D.; Bohn, C.L.; U., /Northern Illinois; Happek, U.; U., /Georgia; Piot, P. et al.
Partner: UNT Libraries Government Documents Department

Manipulation of the longitudinal profile

Description: We present studies of transverse emittances and electron beam pulse length for various operating points of the electron source: electron beam charge, laser length and spot size, and solenoid settings.We especially study the impact, on transverse emittance, of short Gaussian versus long square temporal distributions of the photocathode drive-laser.
Date: January 1, 2006
Creator: Tikhoplav, R.; /UCLA; Kazakevich, G.; /Fermilab; Mihalcea, D.; Piot, P. et al.
Partner: UNT Libraries Government Documents Department

Start-to-end simulation of a Smith-Purcell free electron laser

Description: Terahertz (THz) radiation has generated much recent interest due to its ability to penetrate deep into many organic materials without the damage associated with ionizing radiations. Smith-Purcell free-electron lasers (SPFELs) offer a viable path toward generating copious amounts of narrow-band THz radiation. In this paper we present numerical simulations, performed with the conformal finite-difference time-domain electromagnetic solver VORPAL of a SPFEL operating in the superradiant regime. We first explore the standard (single grating) configuration and investigate the impact of incoming beamparameters. We also present a new concept based a double grating configuration to efficiently bunch the electron beam, followed by a single grating to produce super-radiant SP radiation.
Date: August 1, 2010
Creator: Prokop, C.; U., /Northern Illinois; Piot, P; /Fermilab, /Northern Illinois U.; Lin, M.C.; Stoltz, P. et al.
Partner: UNT Libraries Government Documents Department

Upgrade of the Drive LINAC for the AWA Facility Dielectric Two-Beam Accelerator

Description: We report on the design of a seven-cell, standing-wave, 1.3-GHz rf cavity and the associated beam dynamics studies for the upgrade of the drive beamline LINAC at the Argonne Wakefield Accelerator (AWA) facility. The LINAC design is a compromise between single-bunch operation (100 nC {at} 75 MeV) and minimization of the energy droop along the bunch train during bunch-train operation. The 1.3-GHz drive bunch-train target parameters are 75 MeV, 10-20-ns macropulse duration, and 16 x 60 nC microbunches; this is equivalent to a macropulse current and beam power of 80 A and 6 GW, respectively. Each LINAC structure accelerates approximately 1000 nC in 10 ns by a voltage of 11 MV at an rf power of 10 MW. Due to the short bunch-train duration desired ({approx}10 ns) and the existing frequency (1.3 GHz), compensation of the energy droop along the bunch train is difficult to accomplish by means of the two standard techniques: time-domain or frequency-domain beam loading compensation. Therefore, to minimize the energy droop, our design is based on a large stored energy rf cavity. In this paper, we present our rf cavity optimization method, detailed rf cavity design, and beam dynamics studies of the drive beamline.
Date: July 2, 2012
Creator: Power, John; /Argonne; Conde, Manoel; /Argonne; Gai, Wei; /Argonne et al.
Partner: UNT Libraries Government Documents Department

Design of an electro-optical sampling experiment at the AWA facility

Description: The free space electro-optical (EO) sampling technique is a powerful tool for analyzing the longitudinal charge density of an ultrashort e-beam. In this paper, we present (1) experimental results for a laser-based mock-up of the EO experiment [1] and (2) a design for a beam-based, single-shot, EO sampling experiment using the e-beam from the Argonne Wakefield Accelerator (AWA) RF photoinjector. For the mock-up, a tabletop terahertz experiment is conducted in the AWA laser room. The mock-up uses an IR beam incident on <110> ZnTe crystal to produce a THz pulse via optical rectification. Detection is based on the cross correlation between the THz field and the probe IR laser field in a second <110> ZnTe crystal.
Date: June 1, 2007
Creator: Ruan, J.; Edwards, H.; Tan, Cheng Yang; Thurman-Keup, R.; Scarpine, V.; /Fermilab et al.
Partner: UNT Libraries Government Documents Department

MAPMT H7546B anode current response study for ILC SiD muon system prototype

Description: The proposed Silicon Detector (SiD) concept for the ILC has barrel and end cap muon systems. An SiD scintillator based muon system prototype has 256 strips and was constructed from extruded strips, WLS fibers, clear fibers, and multianode photo multiplier tubes (MAPMT) Hamamatsu H7546B. Six MAPMTs were used. As a first step to understand strip output, the response of every anode to a given brightness of light and applied voltage must be measured. For the test, a custom made light source was used. Each MAPMT output was measured independently. The anode currents were measured at constant (green) input light brightness and the same photocathode to anode voltage (800V). The anode currents have a wide spread; for all tubes the maximum value is 5.23 times larger than the minimum value. The MAPMT cross talk was measured for one of the central inputs. The maximum cross talk value is about 4.9%. The average cross talk for the nearest four neighboring channels is 3.9%, for the farthest four is 1%. To assure the reproducibility and repeatability of the measurements, the double reference method was used.
Date: October 1, 2007
Creator: Dyshkant, A.; Blazey, G.; Francis, K.; Hedin, D.; Zutshi, V.; U., /Northern Illinois et al.
Partner: UNT Libraries Government Documents Department

Quality control studies of wavelength shifting fibers for a scintillator-based tail-catcher muon-tracker linear collider prototype detector

Description: Detailed measurements of the wavelength shifting fiber response to a stable and reliable light source are presented. Details about materials, a double reference method, and measurement technique are included. The fibers studied were several hundred KURARAY, Y-11, multiclad, 1.2mm outer diameter wavelength shifting fibers each cut from a reel to about one meter length. The fibers were polished, mirrored, and the mirrors were UV epoxy protected. Each fiber passed quality control requirements before installation. About 94% of the fibers have a response within 1% of the overall mean.
Date: May 1, 2006
Creator: Dyshkant, A.; Beznosko, D.; Blazey, G.; Rykalin, V.; Zutshi, V.; U., /Northern Illinois et al.
Partner: UNT Libraries Government Documents Department

Simulation of the Microbunching Instability in Beam Delivery Systems for Free Electron Lasers

Description: In this paper, we examine the growth of the microbunching instability in the electron beam delivery system of a free electron laser (FEL). We present the results of two sets of simulations, one conducted using a direct Vlasov solver, the other using a particle-in-cell code Impact-Z with the number of simulation macroparticles ranging up to 100 million. Discussion is focused on the details of longitudinal dynamics and on numerical values of uncorrelated (slice) energy spread at different points in the lattice. In particular, we assess the efficacy of laser heater in suppression of the instability, and look at the interplay between physical and numerical noise in particle-based simulations.
Date: November 2, 2007
Creator: Pogorelov, I.; U., /Northern Illinois; Qiang, J.; Ryne, R.; Venturini, M.; Zholents, A. et al.
Partner: UNT Libraries Government Documents Department

Experimental Plans to Explore Dielectric Wakefield Acceleration in the THZ Regime

Description: Dielectric wakefield accelerators have shown great promise toward high-gradient acceleration. We investigate the performances of a possible experiment under consideration at the FLASH facility in DESY to explore wakefield acceleration with an enhanced transformer ratio. The experiment capitalizes on a unique pulse shaping capability recently demonstrated at this facility. In addition, the facility incorporates a superconducting linear accelerator that could generate bunch trains with closely spaced bunches thereby opening the exploration of potential dynamical effects in dielectric wakefield accelerators.
Date: September 7, 2011
Creator: Lemery, F.; Mihalcea, D.; U., /Northern Illinois; Piot, P.; /Fermilab; Behrens, C. et al.
Partner: UNT Libraries Government Documents Department