14 Matching Results

Results open in a new window/tab.

Kinetics of phase growth in Nb3Sn formation for heat treatment optimization (open access)

Kinetics of phase growth in Nb3Sn formation for heat treatment optimization

The kinetics of growth and superconducting properties of Nb{sub 3}Sn are investigated as a function of the heat treatment (HT) duration and temperature for Internal Tin and Powder-in-Tube strands at 650, 700 and 750 C. For all times and temperatures, the Nb{sub 3}Sn layer thickness is measured, the critical current at 4.2 K is tested as a function of magnetic field, and the upper critical field is evaluated. Results of the layer critical current density are also shown as a function of HT duration and temperature.
Date: October 25, 2002
Creator: Barzi, Emanuela & Mattafirri, Sara
System: The UNT Digital Library
Calorimetry in CDF Run 2 (open access)

Calorimetry in CDF Run 2

The integrated calorimetry environment of CDF Run 2 comprises the Run 1 sampling scintillator calorimeters, electromagnetic preshower and shower maximum detectors, new scintillating-fiber endplug detectors, radioactive source calibration systems, dedicated trigger paths, and new custom front-end electronics. Together they form a general-purpose calorimetry system which was successfully commissioned in 2000/2001. The initial performance is described here, along with a glimpse of first CDF Run 2 data.
Date: October 25, 2002
Creator: Erbacher, R.
System: The UNT Digital Library
Search for CP violation in hyperon decays. (open access)

Search for CP violation in hyperon decays.

Direct CP violation in nonleptonic hyperon decays can be established by comparing the decays of hyperons and anti-hyperons. For {Xi} decay to {Lambda} {pi} followed by {Lambda} to p{pi}, the proton distribution in the rest frame of Lambda is governed by the product of the decay parameters {alpha}{sub {Xi}} {alpha}{sub {Lambda}}. The asymmetry A{sub {Xi}{Lambda}}, proportional to the difference of {alpha}{sub {Xi}}{alpha}{sub {Lambda}} of the hyperon and anti-hyperon decays, vanishes if CP is conserved. We report on an analysis of a fraction of 1997 and 1999 data collected by the Hyper CP (E871) collaboration during the fixed-target runs at Fermilab. The preliminary measurement of the asymmetry is {Alpha}{sub {Xi}{Lambda}} = [-7 {+-} 12(stat) {+-} 6.2(sys)] x 10{sup -4}, an order of magnitude better than the present limit.
Date: October 25, 2002
Creator: Zyla, Piotr
System: The UNT Digital Library
Disappearance of back-to-back high p {sub T} hadron correlations in central Au+Au collisions at {radical}s{sub NN} = 200 GeV (open access)

Disappearance of back-to-back high p {sub T} hadron correlations in central Au+Au collisions at {radical}s{sub NN} = 200 GeV

Azimuthal correlations for large transverse momentum charged hadrons have been measured over a wide pseudo-rapidity range and full azimuth in Au+Au and p+p collisions at = {radical}s{sub NN} = 200 GeV. The small-angle correlations observed in p+p collisions and at all centralities of Au+Au collisions are characteristic of hard-scattering processes already observed in elementary collisions. A strong back-to-back correlation exists for p+p and peripheral Au + Au. In contrast, the back-to-back correlations are reduced considerably in the most central Au+Au collisions, indicating substantial interaction as the hard-scattered partons or their fragmentation products traverse the medium.
Date: October 25, 2002
Creator: Adler, C.; Ahammed, Z.; Allgower, C.; Amonett, J.; Anderson, B. D.; Anderson, M. et al.
System: The UNT Digital Library
The CKM Experiment (open access)

The CKM Experiment

I describe the CKM experiment, a new initiative using the Fermilab Main Injector to obtain {approx} 100 events of the ultra-rare decay mode K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}}. The branching ratio will be used to extract |V*{sub ts}V{sub td}|. Due to the decay mode's theoretical cleanliness, it plays a key role in over-constraining the Standard Model description of CP violation.
Date: October 25, 2002
Creator: Nguyen, Hogan H.
System: The UNT Digital Library
The sodium-cooled fast reactor (SFR). (open access)

The sodium-cooled fast reactor (SFR).

The primary mission for the SFR is the management of high-level wastes, and in particular, management of plutonium and other actinides. The Generation IV Roadmap Fuel Cycle Crosscut Group (FCCG) found that the limiting factor facing an essential role for nuclear energy with the once-through cycle is the availability of repository space worldwide [FCCG Report]. This becomes an important issue, requiring new repository development in only a few decades. Systems that employ a fully closed fuel cycle hold the promise to reduce repository space and performance requirements, although their costs must be held to acceptable levels. Closed fuel cycles, working alone or symbiotically with systems using a once-through cycle, permit partitioning the nuclear waste and management of each partitioned fraction. In the longer term, beyond 50 years, or if major new missions requiring nuclear energy production (such as a major growth in the use of hydrogen as an energy carrier) develop, uranium resource availability also becomes a limiting factor unless breakthroughs occur in mining or extraction technologies. Fast spectrum reactors have the ability to utilize almost all of the energy in the natural uranium versus the 1% utilized in thermal spectrum systems.
Date: October 25, 2002
Creator: Lineberry, M. J. & Allen, T. R.
System: The UNT Digital Library
Searches at the Tevatron (open access)

Searches at the Tevatron

Results of searches performed by CDF and D0 are presented. Most of the results are based on data taken during the 1994-95 data taking period (Run I), but some preliminary results from the current data taking period (Run II) are included.
Date: October 25, 2002
Creator: Orejudos, W.
System: The UNT Digital Library
Silicon detector upgrades for the Tevatron Run 2 (open access)

Silicon detector upgrades for the Tevatron Run 2

The current silicon devices being used by the D0 and CDF collaborations for the Tevatron Run 2a, which is expected to end in 2005 after accumulating about 2 fb{sup -1} of data, will need to be replaced due to radiation damage for the following data collection period designated as Run 2b. We will discuss these silicon replacement plans, the more uniform design of the detectors between D0 and CDF, and the current status of their fabrication.
Date: October 25, 2002
Creator: Kruse, M.
System: The UNT Digital Library
CDF - Secondary vertex trigger (open access)

CDF - Secondary vertex trigger

At the beginning of 2002 a new data taking with an upgraded trigger system started for the CDF collaboration. One of the major improvements is the track trigger. A fast processor reconstructs tracks in the central drift chamber and the Silicon Vertex Tracker combines these tracks with the silicon vertex detector information to have track parameters with a precision as good as the offine reconstruction. This system allows CDF to trigger on tracks significantly displaced from the primary vertex with high efficiency for signal events like charm and beauty and to keep low background rates. The performances, in terms of resolution and efficiency, of both the processors are illustrated and the firsts physics results are discussed.
Date: October 25, 2002
Creator: Lucchesi, D.
System: The UNT Digital Library
A cryomodule for the RIA driver linac. (open access)

A cryomodule for the RIA driver linac.

We present a cryomodule design for the superconducting linacs for the proposed Rare Isotope Accelerator Facility (RIA). This paper discusses the design of a cryomodule for all the drift-tube-loaded superconducting cavities required for the machine. The same basic design will be used for the low and medium velocity sections of the driver linac and also for sections of the radioactive ion beam (RIB) linac. Fundamental design choices such as separate vs. common beam and insulating vacuum spaces are driven by the clean fabrication techniques required for optimum cavity performance. The design can be adapted to a variety of cavity geometries.
Date: October 25, 2002
Creator: Fuerst, J. D. & Shepard, K. W.
System: The UNT Digital Library
Preventing and Removing Contamination in a Natural Radiocarbon Sample Preparation Laboratory (open access)

Preventing and Removing Contamination in a Natural Radiocarbon Sample Preparation Laboratory

The introduction of elevated {sup 14}C contamination into a natural radiocarbon sample preparation laboratory can occur through many different pathways. The most difficult to control is the introduction of contaminated samples from outside labs. Laboratories can remain {sup 14}C contaminated as a result of earlier tracer based research, even if ''hot'' work has not occurred in the laboratories in decades. Prior to accepting samples from outside collaborators, it is recommended that the collaborators test their labs for {sup 14}C contamination. Any surface in a lab that has high use by multiple people has the potential to be contaminated. The standard procedure for determining whether a collaborator's lab is contaminated consists of swiping lab surfaces with small glass fiber filters wetted with alcohol and measuring them for {sup 14}C content using AMS. Volatile {sup 14}C can be detected by using aerosol monitors consisting of fine soot that is depleted in {sup 14}C. These monitors can be set out in the laboratory in question to check for volatile {sup 14}C contamination. In the event that a hot sample is introduced in the natural radiocarbon sample prep laboratory, all sample submission should be stopped until the lab is declared clean. Samples already being …
Date: October 25, 2002
Creator: Zermeno, P.; Kurdyla, D. K.; Buchholz, B. A.; Heller, S. J.; Frantz, B. R.; Brown, T. A. et al.
System: The UNT Digital Library
Inhibition of K+ currents of outer hair cells in guinea pig cochlea by fluoxetine (open access)

Inhibition of K+ currents of outer hair cells in guinea pig cochlea by fluoxetine

Article discussing the inhibition of K+ currents of outer hair cells in guinea pig cochlea by fluoxetine.
Date: October 25, 2002
Creator: Bian, Jing-Tan; Yeh, Jay Z.; Aistrup, Gary L.; Narahashi, Toshio & Moore, Ernest J.
System: The UNT Digital Library
Photon and jet physics at the Collider Detector at Fermilab (open access)

Photon and jet physics at the Collider Detector at Fermilab

We summarize recent Run 1 photon and jet measurements from p{bar b} collisions at {radical}s = 0.63 TeV and 1.8 TeV using data collected at the Collider Detector at Fermilab (CDF). First Run 2 results at {radical}s = 1.96 TeV are also presented together with predictions of the kinematic reach accessible with 15 fb{sup -1} of Run 2 data. Data are compared to the predictions of Quantum Chromodynamics (QCD).
Date: October 25, 2002
Creator: Dittmann, J.
System: The UNT Digital Library
Tevatron magnets and orbit vibrations (open access)

Tevatron magnets and orbit vibrations

We report results of recent measurements of vibrations of the Tevatron collider elements and orbit movements over large diapason of frequencies.
Date: October 25, 2002
Creator: Vladimir Shiltsev, Todd Johnson and Xiao-Long Zhang
System: The UNT Digital Library