Author: Johnstone, C.
Paper Title Page
MOPPC039 Electron Recombination in a Dense Hydrogen Plasma 217
 
  • B.T. Freemire, P.M. Hanlet
    IIT, Chicago, Illinois, USA
  • M. Chung
    Handong Global University, Pohang, Republic of Korea
  • M.G. Collura
    Politecnico di Torino, Torino, Italy
  • M.R. Jana, C. Johnstone, T. Kobilarcik, G.M. Koizumi, M.A. Leonova, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup, Y. Torun, K. Yonehara
    Fermilab, Batavia, USA
  • R.P. Johnson
    Muons, Inc, Batavia, USA
 
  Funding: US DOE under contract DE-AC02-07CH11359.
A high pressure hydrogen gas filled RF cavity was subjected to an intense proton beam to study the evolution of the beam induced plasma inside the cavity. The electron recombination rate with the dense ionized hydrogen plasma has been measured under varying conditions. Recombination rates as high as 10-7 cm3/s have been recorded. This technique shows promise in the R&D program for a muon accelerator. The use of hydrogen, both as a way to prevent breakdown in an RF cavity and as a mechanism for cooling a beam of muons, will be discussed.
 
 
MOPPD084 Optimization of Extinction Efficiency in the 8-GeV Mu2e Beam Line 565
 
  • I.L. Rakhno, A.I. Drozhdin, C. Johnstone, N.V. Mokhov, E. Prebys
    Fermilab, Batavia, USA
 
  Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
A muon-to-electron conversion experiment at Fermilab is being designed to probe for new physics beyond the standard model at mass scales up to 10000 TeV*. The advance in experimental sensitivity is four orders of magnitude when compared to existing data on charged lepton flavor violation. The critical requirement of the experiment is the ability to deliver a proton beam contained in short 100-ns bunches onto a muon production target, with an inter-bunch separation of about 1700 ns. In order to insure the low level of background at the muon detector consistent with the required sensitivity, protons that reach the target between bunches must be suppressed by an enormous factor, 109. This paper describes the results of numerical modeling with STRUCT and MARS codes for a beam line with a collimation system**,*** and optics that achieves an experimental extinction factor of one per billion.
* R.M. Carey et al., Mu2e Proposal, Fermilab (2008).
** W. Molzon, “Proton Beam Extinction,” MECO-EXT-05-002 (2005).
*** E. Prebys, Mu2e-doc-534 (2009), http://mu2e-docdb.fnal.gov.
 
 
MOPPR070 Beam Profile Measurement in MTA Beam Line for High Pressure RF Cavity Beam Test 948
 
  • M.R. Jana, A.D. Bross, S. Geer, C. Johnstone, T. Kobilarcik, G.M. Koizumi, M.A. Leonova, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup, K. Yonehara
    Fermilab, Batavia, USA
  • M. Chung
    Handong Global University, Pohang, Republic of Korea
  • M.G. Collura
    Politecnico di Torino, Torino, Italy
  • B.T. Freemire, P.M. Hanlet, Y. Torun
    IIT, Chicago, Illinois, USA
 
  Funding: This work is supported by the United States Department of Energy under contract DE-AC02-07CH11359.
The recent High Pressure RF (HPRF) cavity experiment at the MuCool Test Area (MTA) used a 400 MeV Linac proton beam to study the beam loading effect. When the energetic proton beam passes through the cavity, it ionizes the inside gas and produces electrons. These electrons consume RF power inside the cavity. The number of electrons produced per cm inside the cavity (at 950 psi Hydrogen gas) per incident proton is 1200. The measurement of beam position and profile are necessary. The MTA is a flammable gas (Hydrogen) hazard zone, so we have developed a passive beam diagnostic instrument using a Chromox-6 scintillation screen and CCD camera. This paper presents quantitative information about beam position and beam profile. A neutral density filter was used to avoid saturation of the CCD camera. Image data is filtered and fitted with a Gaussian function to compute the beam size. The beam profile obtained from the scintillation screen will be compared with a multi-wire beam profile.
 
 
TUPPC044 Emittance and Phase Space Tomography for the Fermilab Linac 1263
 
  • C. Johnstone, F.G.G. Garcia, T. Kobilarcik, G.M. Koizumi, C.D. Moore, D.L. Newhart
    Fermilab, Batavia, USA
 
  Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Dept. of Energy.
The Fermilab Linac delivers a variable intensity, 400-MeV beam to the The MuCool Test Area experimental hall via a beam line specifically designed to facilitate measurements of the Linac beam emittance and properties. A 10 m, dispersion-free and magnet-free straight utilizes an upstream quadrupole focusing triplet in combination with the necessary in-straight beam diagnostics to fully characterize the transverse beam properties. Since the Linac does not produce a strictly elliptical phase space, tomography must be performed on the profile data to retrieve the actual particle distribution in phase space. This is achieved by rotating the phase space distribution using different waist focusing conditions of the upstream triplet and performing a de-convolution of the profile data. Preliminary measurements using this diagnostic section are reported here.
 
 
THEPPB003 A 1 GeV CW FFAG High Intensity Proton Driver 3234
 
  • S.L. Sheehy
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • C. Johnstone
    Fermilab, Batavia, USA
 
  The drive for high beam power, high duty cycle, and reliable beams at reasonable cost has focused world attention on fixed-field accelerators, notably Fixed-Field Alternating Gradient accelerators (FFAGs). High-intensity GeV proton drivers are of particular interest, as these encounter duty cycle and space-charge limits in the synchrotron and machine size concerns in the weaker-focusing cyclotron. Recently, the concept of isochronous orbits has been explored and developed for non-scaling FFAGs using powerful new methodologies in FFAG accelerator design. These new breeds of FFAGs have been identified by international collaborations for serious study thanks to their potential applications including Accelerator Driven Subcritical Reactors (ADS) and Accelerator Transmutation of Waste. The extreme reliability requirements for ADS mandate CW operation capability and the FFAG’s strong focusing, particularly in the vertical, will serve to mitigate the effect of space charge (as compared with the weak-focusing cyclotron). This paper reports on these new advances in FFAG accelerator technology and presents a stable, 0.25-1GeV isochronous FFAG for an accelerator driven subcritical reactor.  
 
THPPR053 A CW FFAG for Proton Computed Tomography 4094
 
  • C. Johnstone, D.V. Neuffer
    Fermilab, Batavia, USA
  • H.L. Owen
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • P. Snopok
    IIT, Chicago, Illinois, USA
 
  Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
An advantage of the cyclotron in proton therapy is the continuous (CW) beam output which reduces complexity and response time in the dosimetry requirements and beam controls. A CW accelerator requires isochronous particle orbits at all energies through the acceleration cycle and present compact isochronous cyclotrons for proton therapy reach only 250 MeV (kinetic energy) which is required for patient treatment, but low for full Proton Computed Tomography (PCT) capability. PCT specifications need 300-330 MeV in order for protons to transit the human body. Recent innovations in nonscaling FFAG design have achieved isochronous performance in a compact (~3 m radius) design at these higher energies. Preliminary isochronous designs are presented here. Lower energy beams can be efficiently extracted for patient treatment without changes to the acceleration cycle and magnet currents.
 
 
THPPR063 1 GeV CW Nonscaling FFAG for ADS, and Magnet Parameters 4118
 
  • F. Méot, W.-T. Weng
    BNL, Upton, Long Island, New York, USA
  • C. Johnstone
    Fermilab, Batavia, USA
  • P. Snopok
    Illinois Institute of Technology, Chicago, IL, USA
 
  Multi-MW proton driver capability remains a challenging, critical technology for many core HEP programs, particularly the neutrino ones such as the Muon Collider and Neutrino factory, and for next generation energy applications such as Accelerator Driven Subcritical Reactors (ADS) and Accelerator Transmutation of Waste for nuclear power and waste management. Work is focused almost exclusively on an SRF linac, as, to date, no re-circulating accelerator can attain the 10-20 MW capability necessary for the nuclear applications. Recently, the concept of isochronous orbits has been explored and developed for nonscaling FFAGs using powerful new methodologies in FFAG accelerator design. The FFAG can remain isochronous beyond the energy reach of cyclotrons and with fixed magnetic fields and strong focusing coupled to recent advances in tune stability, dynamic aperture, and footprint, serious study is underway on a potential application to the ADS problem. Work is progressing on a stable, high intensity, 0.25-1GeV isochronous FFAG. Development and studies of novel magnets with the nonlinear radial fields required to support isochronous operation are reported here.