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Recent RF Results from the MuCool Test Area

Description: The MuCool Experiment has been continuing to take data with805 and 201 MHz cavities in the MuCool Test Area. The system uses rfpower sources from the Fermilab Linac. Although the experimental programisprimarily aimed at the Muon Ionization Cooling Experiment (MICE), wehave been studying the dependence of rf limits on frequency, cavitymaterial, high magnetic fields, gas pressure, coatings, etc. with thegeneral aim of understanding the basic mechanisms involved. The 201 MHzcavity, essentially a prototype for the MICE experiment, was made usingcleaning techniques similar to those employed for superconductingcavities and operates at its design field with very littleconditioning.
Date: June 18, 2007
Creator: Norem, J.; Bross, A.; Moretti, A.; Qian, Z.; Huang, D.; Torun,Y. et al.
Partner: UNT Libraries Government Documents Department

Monte Carlo simulations of muon production

Description: Muon production requirements for a muon collider are presented. Production of muons from pion decay is studied. Lithium lenses and solenoids are considered for focusing pions from a target, and for matching the pions into a decay channel. Pion decay channels of alternating quadrupoles and long solenoids are compared. Monte Carlo simulations are presented for production of {pi} {yields} {mu} by protons over a wide energy range, and criteria for choosing the best proton energy are discussed.
Date: March 1, 1995
Creator: Palmer, R.B.; Gallardo, J.C.; Fernow, R.C.; Torun, Y.; Neuffer, D. & Winn, D.
Partner: UNT Libraries Government Documents Department

The MuCool Test Area and RF Program

Description: The MuCool RF Program focuses on the study of normal conducting RF structures operating in high magnetic field for applications in muon ionization cooling for Neutrino Factories and Muon Colliders. This paper will give an overview of the program, which will include a description of the test facility and its capabilities, the current test program, and the status of a cavity that can be rotated in the magnetic field which allows for a more detailed study of the maximum stable operating gradient vs. magnetic field strength and angle.
Date: May 1, 2010
Creator: Bross, A. D.; Jansson, A.; Moretti, A.; Yonehara, K.; Huang, D.; Torun, Y. et al.
Partner: UNT Libraries Government Documents Department

Recent RF results from the MuCool test area

Description: The MuCool Experiment has been continuing to take data with 805 and 201 MHz cavities in the MuCool Test Area (MTA). The system uses rf power sources from the Fermilab Linac. Although the experimental program is primarily aimed at the Muon Ionization Cooling Experiment (MICE), we have been studying the dependence of rf limits on frequency, cavity material, high magnetic fields, gas pressure, coatings, etc. with the general aim of understanding the basic mechanisms involved. The 201 MHz cavity, essentially a prototype for the MICE experiment, was made using cleaning techniques similar to those employed for superconducting cavities and operates at its design field with very little conditioning.
Date: June 1, 2007
Creator: Norem, J.; Bross, A.; Moretti, A.; Qian, Z.; Huang, D.; Torun, Y. et al.
Partner: UNT Libraries Government Documents Department

The Interactions of Surface Damage on RF Cavity Operation

Description: Studies of low frequency RF systems for muon cooling has led to a variety of new techniques for looking at dark currents, a new model of breakdown, and, ultimately, a model of RF cavity operation based on surface damage. We find that cavity behavior is strongly influenced by the spectrum of enhancement factors on field emission sites. Three different spectra are involved: one defining the initial state of the cavity, the second determined by the breakdown events, and the third defining the equilibrium produced as a cavity operates at its maximum field. We have been able to measure these functions and use them to derive a wide variety of cavity parameters: conditioning behavior, material, pulse length, temperature, vacuum, magnetic field, pressure, gas dependence. In addition we can calculate the dependence of breakdown rate on surface field and pulse length. This work correlates with data from Atom Probe Tomography. We will describe this model and new experimental data.
Date: June 26, 2006
Creator: Norem, J.; Hassanein, A.; Insepov, Z.; Moretti, A.; Qian, Z.; Bross, A. et al.
Partner: UNT Libraries Government Documents Department

The MUCOOL RF Program

Description: Efficient muon cooling requires high RF gradients in the presence of high (3T) solenoidal fields. The Muon Ionization Cooling Experiment (MICE) also requires that the x-ray production from these cavities is low, in order to minimize backgrounds in the particle detectors that must be located near the cavities. These cavities require thin Be windows to ensure the highest fields on the beam axis. In order to develop these cavities, the MUCOOL RF Program was started about 6 years ago. Initial measurements were made on a six-cell cavity and a single-cell pillbox, both operating at 805 MHz. We have now begun measurements of a 201 MHz pillbox cavity. This program has led to new techniques to look at dark currents, a new model for breakdown and a general model of cavity performance based on surface damage. The experimental program includes studies of thin Be windows, conditioning, dark current production from different materials, magnetic-field effects and breakdown.
Date: June 26, 2006
Creator: Norem, J.; Bross, A.; Moretti, A.; Norris, B.; Qian, Z.; Torun, Y. et al.
Partner: UNT Libraries Government Documents Department

Effect of high solenoidal magnetic fields on breakdown voltages of high vacuum 805 MHz cavities

Description: There is an on going international collaboration studying the feasibility and cost of building a muon collider or neutrino factory [1,2]. An important aspect of this study is the full understanding of ionization cooling of muons by many orders of magnitude for the collider case. An important muon ionization cooling experiment, MICE [3], has been proposed to demonstrate and validate the technology that could be used for cooling. Ionization cooling is accomplished by passing a high-emittance muon beam alternately through regions of low Z material, such as liquid hydrogen, and very high accelerating RF Cavities within a multi-Tesla solenoidal field. To determine the effect of very large solenoidal magnetic fields on the generation of dark current, x-rays and on the breakdown voltage gradients of vacuum RF cavities, a test facility has been established at Fermilab in Lab G. This facility consists of a 12 MW 805 MHz RF station and a large warm bore 5 T solenoidal superconducting magnet containing a pill box type cavity with thin removable window apertures. This system allows dark current and breakdown studies of different window configurations and materials. The results of this study will be presented. The study has shown that the peak achievable accelerating gradient is reduced by a factor greater than 2 when solenoidal field of greater than 2 T are applied to the cavity.
Date: October 1, 2005
Creator: Moretti, A.; Bross, A.; Geer, S.; Qian, Z.; Norem, J.; Li, D. et al.
Partner: UNT Libraries Government Documents Department

The US Muon Accelerator Program

Description: An accelerator complex that can produce ultra-intense beams of muons presents many opportunities to explore new physics. A facility of this type is unique in that, in a relatively straightforward way, it can present a physics program that can be staged and thus move forward incrementally, addressing exciting new physics at each step. At the request of the US Department of Energy's Office of High Energy Physics, the Neutrino Factory and Muon Collider Collaboration (NFMCC) and the Fermilab Muon Collider Task Force (MCTF) have recently submitted a proposal to create a Muon Accelerator Program that will have, as a primary goal, to deliver a Design Feasibility Study for an energy-frontier Muon Collider by the end of a 7 year R&D program. This paper presents a description of a Muon Collider facility and gives an overview of the proposal.
Date: May 1, 2010
Creator: Torun, Y.; /IIT, Chicago; Kirk, H.; /Brookhaven; Bross, A.; Geer, Steve et al.
Partner: UNT Libraries Government Documents Department

The rf experimental program in the fermilab mucool test area

Description: The rf R&D program for high-gradient, low frequency cavities to be used in muon cooling systems is underway in the Fermilab MUCOOL Test Area. Cavities at 805 and 201 MHz are used for tests of conditioning techniques, surface modification and breakdown studies. This work has the Muon Ionization Cooling Experiment (MICE) as its immediate goal and efficient muon cooling systems for neutrino sources and muon colliders as the long term goal. We study breakdown and dark current production under a variety of conditions.
Date: May 20, 2005
Creator: Norem, J.; Sandstrom, R.; Bross, A.; Moretti, A.; Qian, Z.; Torun, Y. et al.
Partner: UNT Libraries Government Documents Department

High-energy high-luminosity {mu}{sup +}{mu}{sup {minus}} collider design

Description: We discuss the design of a high luminosity (l0{sup 35} cm-{sup {minus}2} s{sup {minus}1}), high energy (2 + 2 TeV) {mu}{sup +}{mu}{sup {minus}} collider, starting from the proton accelerator needed to generate the muon beams and proceeding through the muon storage ring.
Date: July 1, 1995
Creator: Palmer, R.B.; Fernow, R.; Gallardo, J.C.; Lee, Y.Y.; Torun, Y.; Neuffer, D. et al.
Partner: UNT Libraries Government Documents Department

The effects of surface damage on RF cavity operation

Description: We describe a model of damage in rf cavities and show how this damage can limit cavity operation. We first present a review of mechanisms that may or may not affect the ultimate fields that can be obtained in rf cavities, assuming that mechanical stress explains the triggers of rf breakdown events. We present a method of quantifying the surface damage caused by breakdown events in terms of the spectrum of field enhancement factors, Beta, for asperities on the surface. We then model an equilibrium that can develop between damage and conditioning effects, and show how this equilibrium can determine cavity performance and show experimental evidence for this mechanism. We define three functions that quantify damage, and explain how the parameters that determine this performance can be factored out and measured. We then show how this model can quantitatively explain the dependence of cavity performance on material, frequency, pulse length, gas, power supply and other factors. The examples given in this paper are derived from a variety of incomplete data sets, so we outline an experimental program that should improve these predictions, provide mechanisms for comparing data from different facilities, and fill in many gaps in the existing data.
Date: April 14, 2006
Creator: Hassanein, A.; Insepov, Z.; Norem, J.; Moretti, A.; Qian, Z.; Bross, A. et al.
Partner: UNT Libraries Government Documents Department

The MuCool Test Area and RF Program

Description: The MuCool RF Program focuses on the study of normal conducting RF structures operating in high magnetic field for applications in muon ionization cooling for Neutrino Factories and Muon Colliders. Here we give an overview of the program, which includes a description of the test facility and its capabilities, the current test program, and the status of a cavity that can be rotated in the magnetic field, which allows for a detailed study of the maximum stable operating gradient vs. magnetic field strength and angle.
Date: May 1, 2010
Creator: Torun, Y.; Huang, D.; /IIT, Chicago; Norem, J.; /Argonne; Palmer, Robert B. et al.
Partner: UNT Libraries Government Documents Department

RF tests of an 805 MHz pillbox cavity at Lab G of Fermilab

Description: We report recent high power RF tests on an 805 MHz RF pillbox cavity with demountable windows for beam apertures at Lab G of Fermilab, a dedicated facility for testing of MUCOOL (muon cooling) components. The cavity is installed inside a superconducting solenoidal magnet. A 12 MW peak RF power klystron is used for the tests. The cavity has been processed both with and without magnetic field. Without magnetic field, a gradient of 34 MV/m was reached rather quickly with very low sparking rate. In a 2.5 T solenoidal field, a 16 MV/m gradient was achieved, and it had to take many weeks of conditioning. Strong multipacting effects associated with high radiation levels were measured during the processing with the magnetic field. More recently Be windows with TiN-coated surface have been installed and tested at conditions of with and without the external magnetic field. A conservative 16 MV/m gradient without magnetic field was reached quickly as planned. Less multipacting was observed during the conditioning, it indicated that the TiN-coated surface on the windows had indeed helped to reduce the secondary electron emissions significantly. A modest gradient of 16.5 MV/m was finally achieved with magnet on in solenoidal mode and the field up to 4 T. Preliminary inspection on Be windows surface found no damage at all, in comparison with Cu windows where substantial surface damage was found. Preliminary understanding of conditioning cavity in a strong magnetic field has been developed. More through window and cavity surface inspection is under way.
Date: May 1, 2003
Creator: Li, Derun; Corlett, J.; MacGill, R.; Wallig, J.; Zisman, M.; Moretti, A. et al.
Partner: UNT Libraries Government Documents Department

Proposal to upgrade the MIPP experiment

Description: The upgraded MIPP physics results are needed for the support of NuMI projects, atmospheric cosmic ray and neutrino programs worldwide and will permit a systematic study of non-perturbative QCD interactions. The MIPP TPC is the largest contributor to the MIPP event size by far. Its readout system and electronics were designed in the 1990's and limit it to a readout rate of 60 Hz in simple events and {approx} 20 Hz in complicated events. With the readout chips designed for the ALICE collaboration at the LHC, we propose a low cost scheme of upgrading the MIPP data acquisition speed to 3000 Hz. This will also enable us to measure the medium energy numi target to be used for the NOvA/MINERvA experiments. We outline the capabilities of the upgraded MIPP detector to obtain high statistics particle production data on a number of nuclei that will help towards the understanding and simulation of hadronic showers in matter. Measurements of nitrogen cross sections will permit a better understanding of cosmic ray shower systematics in the atmosphere. In addition, we explore the possibilities of providing tagged neutral beams using the MIPP spectrometer that may be crucial for validating the Particle Flow Algorithm proposed for calorimeters for the International Linear Collider detectors. Lastly, we outline the physics potential of such a detector in understanding non-perturbative QCD processes.
Date: September 1, 2006
Creator: Isenhower, D.; Sadler, M.; Towell, R.; Watson, S.; Peterson, R. J.; Baker, W. et al.
Partner: UNT Libraries Government Documents Department

Accelerator Design Concept for Future Neutrino Facilities

Description: This document summarizes the findings of the Accelerator Working Group (AWG) of the International Scoping Study (ISS) of a Future Neutrino Factory and Superbeam Facility. The work of the group took place at three plenary meetings along with three workshops, and an oral summary report was presented at the NuFact06 workshop held at UC-Irvine in August, 2006. The goal was to reach consensus on a baseline design for a Neutrino Factory complex. One aspect of this endeavor was to examine critically the advantages and disadvantages of the various Neutrino Factory schemes that have been proposed in recent years.
Date: February 3, 2008
Creator: Group, ISS Accelerator Working; Zisman, Michael S; Berg, J. S.; Blondel, A.; Brooks, S.; Campagne, J.-E. et al.
Partner: UNT Libraries Government Documents Department

Search for CP violation in hyperon decays.

Description: 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; Chan, A.; Chen, Y.C.; Ho, C.; Teng, P.K.; Choong, W.S. et al.
Partner: UNT Libraries Government Documents Department