122322377
Rescattering in 100-GeV/c proton-deuteron and positive-pion--deuteron interactions
We have studied rescattering in 100-GeV/c proton and positive-pion interactions with deuterons in the Fermilab 30-in. bubble chamber. We study specifically events in which the deuteron breaks up and meson production occurs. After attempting to take account of elastic rescattering, we determine the fraction of events in which rescattering occurs, and the multiplicity distribution of the rescatter events. The rescatter fraction found for 100-GeV/c ..pi../sup +/d events is consistent with the values found in 21-GeV/c and 205-GeV/c ..pi../sup -/d experiments while the fraction found for 100-GeV/c pd events is slightly larger. The multiplicity distributions in the rescatter events are in reasonable agreement with 205-GeV/c pp or ..pi../sup -/p multiplicity distributions. We compare our results to predictions of energy-flux-cascade and coherent-tube models.
95691104
Preparing crystals for channeling experiments at high energies
Abstract On the basis of the experience of silicon crystal preparation for two Fermilab experiments on particle channeling (E761 and E853) the requirements for the crystal perfection for high energy physics experiments are discussed. Techniques which provide the cutting, orientation with high accuracy and test the quality of the initial and completed crystals are presented.
125857609
A Search for the production of prompt neutrinos in high energy proton nucleus collisions
122051077
Results from experiments of crystal extraction of 900 GeV proton beams from the Tevatron Collider
The extraction of a small flux of primary protons from a collider in a parasitic manner is very attractive for a number of fixed target applications. The key requirements of the extracted beam are small average currents with relatively small temporal variations. At this time a bent crystal is installed in the Tevatron Collider which is designed to channel protons down an instrumented beam abort transfer line. In this paper the results of experiments with this crystal are presented. The impact on the high energy physics collider detectors of the crystal as a collimator and the transverse mechanism necessary to deposit the protons into the crystal for alignment purposes are described.
120121929
Characteristics of the radiation damage seen in the silicon microstrip detector of Fermilab experiment E771
The central region of the silicon microstrip detector used in Fermilab experiment E771 was subjected to a peak fluence of 9.5 × 1013 p/cm2 induced by 800 GeV protons over a two-month period. Fourteen 300 μm thick planes manufactured by Micron Semiconductor were operated at bias voltages ranging from 84 to 109 V. Analysis of data from low intensity beam triggers taken near the end of the run shows that the mean pulse height from our amplifiers began to decline at a fluence of approximately 2 × 1013 p/cm2 and fell to near zero by 6 × 1013 p/cm2. We show that the use of fast amplifiers contributed to this early loss of signal.
116956262
Design of a crystal extraction facility in the east utility straight
Parasitic extraction of a small fraction of the 20-TeV circulating beam of the Superconducting Super Collider can be done using a bent crystal situated in the halo of the orbiting beam. The authors present a design of a crystal extraction system that is compatible with current plans for momentum scraping in the east utility straight. The only modification to the collider tunnel is the addition of a 160-m-long alcove in the east utility straight to mate the extracted beam line microtunnel with the collider tunnel. No other changes to the east utility straight tunnel are needed.
25180848
A high precision, compact electromechanical ground rotation sensor.
We present a mechanical rotation sensor consisting of a balance pivoting on a tungsten carbide knife edge. These sensors are important for precision seismic isolation systems, as employed in land-based gravitational wave interferometers and for the new field of rotational seismology. The position sensor used is an air-core linear variable differential transformer with a demonstrated noise floor of 1 × 10⁻¹¹ m/√Hz. We describe the instrument construction and demonstrate low noise operation with a noise floor upper bound of 5.7 × 10⁻⁹ rad/√Hz at 10 mHz and 6.4 × 10⁻¹⁰ rad/√Hz at 0.1 Hz. The performance of the knife edge hinge is compatible with a behaviorur free of noise from dislocation self-organized criticality.
172822549
Inclusive J / $\psi$ Production at D0
55399019
Massive spin-2 states as the origin of the top quark forward-backward asymmetry
We show that the anomalously large top quark forward-backward asymmetry observed by CDF and DØ can naturally be accommodated in models with flavor-violating couplings of a new massive spin-2 state to quarks. Regardless of its origin, the lowest-order couplings of a spin-2 boson to fermions are analogous to the coupling of the graviton to energy/momentum, leading to strong sensitivity of the effects associated with its virtual exchange to the energy scales at hand. Precisely due to this fact, the observed dependence of the asymmetry on the $ t\overline t $ invariant mass fits nicely into the proposed framework. In particular, we find a vast parameter space which can lead to the central value for the observed forward-backward asymmetry in the high mass bin.
122070076
Muon trigger electronics for hadron collider experiments
Abstract Trigger electronics designed and constructed for the SDC muon system are described briefly and results of beam tests carried out at KEK are presented. The implementation is based on custom VLSI designs in 1.2 μm CMOS. The performance characteristics of the circuits were measured and confirmed to meet specifications. Designs based on this approach are applicable to future collider experiments.
110445102
Operating a production pilot factory serving several scientific domains
Pilot infrastructures are becoming prominent players in the Grid environment. One of the major advantages is represented by the reduced effort required by the user communities (also known as Virtual Organizations or VOs) due to the outsourcing of the Grid interfacing services, i.e. the pilot factory, to Grid experts. One such pilot factory, based on the glideinWMS pilot infrastructure, is being operated by the Open Science Grid at University of California San Diego (UCSD). This pilot factory is serving multiple VOs from several scientific domains. Currently the three major clients are the analysis operations of the HEP experiment CMS, the community VO HCC, which serves mostly math, biology and computer science users, and the structural biology VO NEBioGrid. The UCSD glidein factory allows the served VOs to use Grid resources distributed over 150 sites in North and South America, in Europe, and in Asia. This paper presents the steps taken to create a production quality pilot factory, together with the challenges encountered along the road.