Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics (open access)

Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

The Large Hadron Collider (LHC) at CERN promises a major step forward in the understanding of the fundamental nature of matter. The ATLAS experiment is a general-purpose detector for the LHC, whose design was guided by the need to accommodate the wide spectrum of possible physics signatures. The major remit of the ATLAS experiment is the exploration of the TeV mass scale where groundbreaking discoveries are expected. In the focus are the investigation of the electroweak symmetry breaking and linked to this the search for the Higgs boson as well as the search for Physics beyond the Standard Model. In this report a detailed examination of the expected performance of the ATLAS detector is provided, with a major aim being to investigate the experimental sensitivity to a wide range of measurements and potential observations of new physical processes. An earlier summary of the expected capabilities of ATLAS was compiled in 1999 [1]. A survey of physics capabilities of the CMS detector was published in [2]. The design of the ATLAS detector has now been finalised, and its construction and installation have been completed [3]. An extensive test-beam programme was undertaken. Furthermore, the simulation and reconstruction software code and frameworks have …
Date: November 28, 2011
Creator: Aad, G.; Abat, E.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A. et al.
System: The UNT Digital Library
Design and Factory Test of the E /E- Frascati Linear Accelerator for DAFNE (open access)

Design and Factory Test of the E /E- Frascati Linear Accelerator for DAFNE

The electron-positron accelerator for the DAFNE project has been built and is in test at Titan Beta in Dublin, CA. This S-Band RF linac system utilizes four 45 MW sledded klystrons and 16-3 m accelerating structures to achieve the required performance. It delivers a 4 ampere electron beam to the positron converter and accelerates the resulting positrons to 550 MeV. The converter design uses a 4.3T pulsed tapered flux compressor along with a pseudo-adiabatic tapered field to a 5 KG solenoid over the first two positron accelerating sections. Quadrupole focusing is used after 100 MeV. The system performance is given in Table 1. This paper briefly describes the design and development of the various subassemblies in this system and gives the initial factory test data.
Date: November 28, 2011
Creator: Anamkath, H.; Lyons, S.; Nett, D.; Treas, P.; Whitham, K.; Zante, T. et al.
System: The UNT Digital Library
B Decay and CP Violation: CKM Angles and Sides at the BABAR and BELLE B-Factories (open access)

B Decay and CP Violation: CKM Angles and Sides at the BABAR and BELLE B-Factories

A remarkable success has been achieved by the B-Factories, going beyond expectation in some field, like the measurement of {gamma}. BABAR has now finished its data taking, leaving BELLE alone in the 'race', but still many analyses are going on. The CKM UT is constrained by both measurements of CP-conserving and CP-violating quantities, leading to a picture of the CKM sector consistent with the SM. Measurements of semi-leptonic decays benefit from improving experimental techniques and more precise theoretical computations. The angle {beta} is a precision measurement, reaching accuracy of SM calculation. The angle {alpha} will ultimatly be limited by penguin pollution. The measurement of {gamma} is reaching the 13{sup o} precision.
Date: November 28, 2011
Creator: Verderi, Marc & Polytechnique, /Ecole
System: The UNT Digital Library
Long-Range And Head-On Beam-Beam Compensation Studies in RHIC With Lessons for the LHC (open access)

Long-Range And Head-On Beam-Beam Compensation Studies in RHIC With Lessons for the LHC

Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are are also important consideration for the LHC upgrades. To mitigate long-range effects, current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. Electron lenses were proposed for both RHIC and the LHC to reduce the head-on beam-beam effect. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.
Date: November 28, 2011
Creator: Fischer, W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G. et al.
System: The UNT Digital Library
Novel Approach to Linear Accelerator Superconducting Magnet System (open access)

Novel Approach to Linear Accelerator Superconducting Magnet System

Superconducting Linear Accelerators include a superconducting magnet system for particle beam transportation that provides the beam focusing and steering. This system consists of a large number of quadrupole magnets and dipole correctors mounted inside or between cryomodules with SCRF cavities. Each magnet has current leads and powered from its own power supply. The paper proposes a novel approach to magnet powering based on using superconducting persistent current switches. A group of magnets is powered from the same power supply through the common, for the group of cryomodules, electrical bus and pair of current leads. Superconducting switches direct the current to the chosen magnet and close the circuit providing the magnet operation in a persistent current mode. Two persistent current switches were fabricated and tested. In the paper also presented the results of magnetic field simulations, decay time constants analysis, and a way of improving quadrupole magnetic center stability. Such approach substantially reduces the magnet system cost and increases the reliability.
Date: November 28, 2011
Creator: Kashikhin, Vladimir
System: The UNT Digital Library
Femtosecond X-ray Pulse Characterization in Free-electron Lasers using a Cross-correlation Technique (open access)

Femtosecond X-ray Pulse Characterization in Free-electron Lasers using a Cross-correlation Technique

None
Date: November 28, 2012
Creator: Ding, Y.; Decker, F. J.; Emma, P.; Feng, C.; Field, C.; Frisch, J. et al.
System: The UNT Digital Library
Event-by-Event Evaluation of the Prompt Fission Neutron Spectrum From 239pu(N,F) (open access)

Event-by-Event Evaluation of the Prompt Fission Neutron Spectrum From 239pu(N,F)

We have developed an improved evaluation method for the spectrum of neutrons emitted in fission of {sup 239}Pu induced by incident neutrons with energies up to 20 MeV. The <v> covariance data, including incident energy correlations introduced by the <v> evaluation method, were used to fix the input parameters in our event-by-event model of fission, FREYA, by applying formal statistical methods. Formal estimates of uncertainties in the evaluation were developed by randomly sampling model inputs and calculating likelihood functions based on agreement with the evaluated <v>. Our approach is able to employ a greater variety of fission measurements than the relatively coarse spectral data alone. It also allows the study of numerous fission observables for more accurate model validation. The combination of an event-by-event Monte Carlo fission model with a statistical-likelihood analysis is thus a powerful tool for evaluation of fission-neutron data. Our empirical model FREYA follows the complete fission event from birth of the excited fragments through their decay via neutron emission until the fragment excitation energy is below the neutron separation energy when neutron emission can no longer occur. The most recent version of FREYA incorporates pre-equilibrium neutron emission, the emission of the first neutron before equilibrium is …
Date: November 28, 2011
Creator: Vogt, R.; Randrup, J.; Brown, D. A.; Descalle, M. A. & Ormand, W. E.
System: The UNT Digital Library
Real-Time Speech Masking Using EM-Wave Acoustic Sensors (open access)

Real-Time Speech Masking Using EM-Wave Acoustic Sensors

None
Date: November 28, 2012
Creator: Holzrichter, J F; Ng, L C & Chang, J T
System: The UNT Digital Library
Design and Fabrication of a Single-Aperture 11T Nb3Sn Dipole Model for LHC Upgrades (open access)

Design and Fabrication of a Single-Aperture 11T Nb3Sn Dipole Model for LHC Upgrades

The planned upgrade of the LHC collimation system includes additional collimators to be installed in the dispersion suppressor areas of points 2, 3 and 7. To provide the necessary longitudinal space for the collimators, a replacement of 8.33 T Nb-Ti LHC main dipoles with 11 T dipoles based on Nb{sub 3}Sn superconductor compatible with the LHC lattice and main systems is being considered. To demonstrate this possibility FNAL and CERN have started a joint program to develop a 2 m long single-aperture dipole magnet with the nominal field of 11 T at {approx}11.85 kA current and 60 mm bore. This paper describes the demonstrator magnet magnetic and mechanical designs and analysis, coil fabrication procedure. The Nb{sub 3}Sn strand and cable parameters and test results are also reported.
Date: November 28, 2011
Creator: Andreev, N.; Apollinari, G.; Barzi, E.; Bossert, R.; Nobrega, F.; Novitski, I. et al.
System: The UNT Digital Library
Collective Deceleration: Toward a Compact Beam Dump (open access)

Collective Deceleration: Toward a Compact Beam Dump

With the increasing development of laser accelerators, the electron energy is already beyond GeV and even higher in near future. Conventional beam dump based on ionization or radiation loss mechanism is cumbersome and costly, also has radiological hazards. We revisit the stopping power of high-energy charged particles in matter and discuss the associated problem of beam dump from the point of view of collective deceleration. The collective stopping length in an ionized gas can be several orders of magnitude shorter than the Bethe-Bloch and multiple electromagnetic cascades stopping length in solid. At the mean time, the tenuous density of the gas makes the radioactivation negligible. Such a compact and non-radioactivating beam dump works well for short and dense bunches, which is typically generated from laser wakefield accelerator.
Date: November 28, 2011
Creator: Wu, H.-C.; Tajima, T.; Habs, D.; Chao, A.W. & Meyer-ter-Vehn, J.
System: The UNT Digital Library
Radioargon production through the irradiation of calcium oxide (open access)

Radioargon production through the irradiation of calcium oxide

None
Date: November 28, 2012
Creator: Egnatuk, C M & Biegalski, S R
System: The UNT Digital Library