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The Longitudinal Stability of Intense Non-Relativistic Particle Bunches in Resistive Structures

Description: The longitudinal stability of intense particle bunches is investigated theoretically in the limit of small wall resistivity compared to total reactance. It is shown that both in the absence of resistivity and to lowest order in the resistance that an intense bunch is stable against longitudinal collective modes. An expression is derived for the lowest order instability rate. Application of these results are made to drivers for heavy ion inertial fusion.
Date: February 1, 1981
Creator: Channell, P. J.; Sessler, A. M. & Wurtele, J. S.
Partner: UNT Libraries Government Documents Department

Longitudinal Resistive Stability of an Intense Charge Bunch in a Linear Accelerator

Description: A simple, but realistic, model is used to theoretically investigate the longitudinal stability of a non-relativistic bunch in the limit of small wall resistivity compared to self-reactance. It is shown that to lowest order--and in contrast with an infinitely long beam--that an intense bunch is stable against longitudinal collective modes. It is concluded that an induction linac remains a viable option as a driver for heavy ion inertial fusion.
Date: July 1, 1980
Creator: Channell, P.J.; Wurtele, J.S. & Sessler, A.M.
Partner: UNT Libraries Government Documents Department

Planning for an integrated research experiment

Description: We describe the goals and research program leading to the Heavy Ion Integrated Research Experiment (IRE). We review the basic constraints which lead to a design and give examples of parameters and capabilities of an IRE. We also show design tradeoffs generated by the systems code IBEAM.
Date: March 25, 2001
Creator: Barnard, J.J.; Ahle, L.E.; Bangerter, R.O.; Bieniosek, F.M.; Celata, C.M.; Faltens, A. et al.
Partner: UNT Libraries Government Documents Department

Exposing the non-collectivity in elliptic flow

Description: We show that backward-forward elliptic asymmetry correlations provide an experimentally accessible observable which distinguishes between collective and non-collective contributions to the observed elliptic asymmetry v2 in relativistic heavy ion collisions. The measurement of this observable will reveal the momentum scale at which collective expansion seizes and where the elliptic asymmetry is dominated by (semi)-hard processes. In addition, the knowledge of the actual magnitude of the collective component of the elliptic asymmetry will be essential for the extraction of the viscosity of the matter created in these collisions.
Date: February 13, 2009
Creator: Liao, Jinfeng & Koch, Volker
Partner: UNT Libraries Government Documents Department

Exact Relativistic Ideal Hydrodynamical Solutions in (1+3)D with Longitudinal and Transverse Flows

Description: A new method for solving relativistic ideal hydrodynamics in (1+3)D is developed. Longitudinal and transverse radial flows are explicitly embedded into the ansatz for velocity field and the hydrodynamic equations are reduced to a single equation for the transverse velocity field only, which is analytically more tractable as compared with the full hydrodynamic equations. As an application we use the method to find analytically all possible solutions whose transverse velocity fields have power dependence on proper time and transverse radius. Possible application to the Relativistic Heavy Ion Collisions and possible generalizations of the method are discussed.
Date: May 20, 2009
Creator: Liao, Jinfeng & Koch, Volker
Partner: UNT Libraries Government Documents Department

Sensor Development and Readout Prototyping for the STAR Pixel Detector

Description: The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) is designing a new vertex detector. The purpose of this upgrade detector is to provide high resolution pointing to allow for the direct topological reconstruction of heavy flavor decays such as the D{sup 0} by finding vertices displaced from the collision vertex by greater than 60 microns. We are using Monolithic Active Pixel Sensor (MAPS) as the sensor technology and have a coupled sensor development and readout system plan that leads to a final detector with a <200 {micro}s integration time, 400 M pixels and a coverage of -1 < {eta} < 1. We present our coupled sensor and readout development plan and the status of the prototyping work that has been accomplished.
Date: January 14, 2009
Creator: Greiner, L.; Anderssen, E.; Matis, H. S.; Ritter, H. G.; Stezelberger, T.; Szelezniak, M. et al.
Partner: UNT Libraries Government Documents Department

Fragmentation cross sections of 28Si at beam energies from 290AMeV to 1200A MeV

Description: In planning for long-duration spaceflight, it will beimportant to accurately model the exposure of astronauts to heavy ions inthe Galactic Cosmic Rays (GCR). As part of an ongoing effort to improveheavy-ion transport codes that will be used in designing futurespacecraft and habitats, fragmentation cross sections of 28Si have beenmeasured using beams with extracted energies from 290A MeV to 1200A MeV,spanning most of the peak region of the energy distribution of siliconions in the GCR. Results were obtained for six elemental targets:hydrogen, carbon, aluminum, copper, tin, and lead. The charge-changingcross sections are found to be energy-independent within the experimentaluncertainties, except for those on the hydrogen target. Cross sectionsfor the heaviest fragments are found to decrease slightly with increasingenergy for lighter targets, but increase with energy for tin and leadtargets. The cross sections are compared to previous measurements atsimilar energies, and to predictions of the NUCFRG2 model used by NASA toevaluate radiation exposures in flight. For charge-changing crosssections, reasonable agreement is found between the present experimentand those of Webber, et al. and Flesch, et al., and NUCFRG2 agrees withthe data to within 3 percent in most cases. Fragment cross sections showless agreement between experiments, and there are substantial differencesbetween NUCFRG2 predictions andthe data.
Date: August 25, 2006
Creator: Zeitlin, C.; Fukumura, A.; Guetersloh, S.B.; Heilbronn, L.H; Iwata, Y.; Miller, J. et al.
Partner: UNT Libraries Government Documents Department

Highly-charged heavy-ion production with short pulse lasers

Description: This MathCAD document describes a possible approach using a PW -class short pulse laser to form a useful number (10{sup 12}) of high and uniform charge state ions with low ion temperature (<< 100 eV) and low momentum spread ({delta}p{sub z}/p, < 10{sup -4} ) for injection into heavy-ion fusion accelerators. As a specific example, we consider here Xenon{sup +26}, which has an ionization energy E{sub i} {approximately} 860 eV for the 26th electron, and a significantly higher ionization potential of 1500 eV for the 27th electron because of the M-shell jump. The approach considered here may be used for other ion species as well. The challenge is not simply to produce high charge states with a laser (the ITEP group [Sharkov] have used long pulse CO{sub 2} lasers to create many charge states of chromium up to helium-like Cr{sup +25} by collisional ionization at high Te), nor just to create such high charge states more selectively by field (tunneling) ionization at higher intensities and shorter pulses. Rather, the challenge is to create a selected uniform high charge state, in useful numbers, while keeping the ion temperature and momentum spread small, and avoiding subsequent loss of ion charge state due to recombination and charge-exchange with background gas atoms during extraction into a useful low emittance beam.
Date: January 27, 1998
Creator: Logan, G.; Bitmire, T.; Perry, M.; Anderson, O. & Kuehl, T.
Partner: UNT Libraries Government Documents Department

The source of elliptic flow and initial conditions for hydrodynamical calculations

Description: A model for energy, pressure and flow velocity distributions at the beginning of relativistic heavy ion collisions is presented, which can be used as initial condition for hydrodynamical calculations. The results show that QGP forms a tilted disk, such that the direction of the largest pressure gradient stays in the reaction plane, but deviates from both the beam and the usual transverse flow directions. Such initial condition may lead to the creation of antiflow or third flow component.
Date: August 2000
Creator: Strottman, D.; Csernai, L. & Magas, V.
Partner: UNT Libraries Government Documents Department


Description: In this talk, the author discusses the scientific issues being addressed in ultrarelativistic heavy ion collisions. He also discusses some of the recent results from RHIC at Brookhaven National Laboratory which give some experimental insight into these issues.
Date: June 24, 2002
Creator: MCLERRAN,L.
Partner: UNT Libraries Government Documents Department


Description: Electron cloud is found to be a serious obstacle on the upgrade path of the Relativistic Heavy Ion Collider (RHIC). At twice the design number of bunches, electron-ion interactions cause significant instability, emittance growth, and beam loss along with vacuum pressure rises when the beam is accelerated across the transition.
Date: May 16, 2005
Creator: WEI,J.; IRISO, U.; BAI, M. & AL., ET
Partner: UNT Libraries Government Documents Department

Tomographic Measurement of Longitudinal Emittance Growth Due to Stripping Foils.

Description: During beam acceleration in the Brookhaven accelerator complex, heavy ions are stripped of their electrons in several steps. Depending on the properties of the stripping foils, this process results in an increased energy spread and longitudinal emittance growth. A tomographic phase space reconstruction technique has been applied to measure the associated emittance growth for different stripping foil materials.
Date: May 16, 2005
Creator: Montag, C.; Ahrens, L. & Thieberger, P.
Partner: UNT Libraries Government Documents Department


Description: In this paper, we discuss various electron cooling dynamics studies for RHIC. We also present simulations [1] of various possibilities of using electron cooling at RHIC, which includes cooling at the top energy, pre-cooling at low energy, aspects of transverse and longitudinal cooling and their impact on the luminosity. Electron cooling at various collision energies both for heavy ions and protons is also discussed.
Date: May 16, 2005
Partner: UNT Libraries Government Documents Department

Compact High-Current Heavy-Ion Injector

Description: To provide a compact high-brightness heavy-ion beam source for Heavy Ion Fusion (HIF), we have been experimenting with merging multi-beamlets in an injector which uses an RF plasma source. An array of converging beamlets was used to produce a beam with the envelope radius, convergence, and ellipticity matched to an electrostatic quadrupole (ESQ) channel. Experimental results were in good quantitative agreement with simulation and have demonstrated the feasibility of this concept. The size of a driver-scale injector system using this approach will be several times smaller than one designed using traditional single large-aperture beams. The success of this experiment has possible significant economical and technical impacts on the architecture of HIF drivers.
Date: October 5, 2005
Creator: Westenskow, G. A.; Grote, D. P.; Kwan, J. W. & Bieniosek, F.
Partner: UNT Libraries Government Documents Department

Laser ion source for low charge heavy ion beams

Description: For heavy ion inertial fusion application, a combination of a laser ion source and direct plasma injection scheme into an RFQ is proposed. The combination might provide more than 100 mA of singly charged heavy ion beam from a single laser shot. A planned feasibility test with moderate current is also discussed.
Date: August 3, 2008
Creator: Okamura, M.; Pikin, A.; Zajic, V.; Kanesue, T. & Tamura, J.
Partner: UNT Libraries Government Documents Department


Description: Polarized protons are injected into the Relativistic Heavy Jon Collider (RHIC) just above transition energy. When installation of a cold partial Siberian snake in the AGS required lowering the injection energy by {Delta}{gamma} = 0.56, the transition energy in RHIC had to be lowered accordingly to ensure proper longitudinal matching. This paper presents lattice modifications implemented to lower the transition energy by {Delta}{gamma}{sub t} = 0.8.
Date: June 25, 2007
Creator: MONTAG,C.
Partner: UNT Libraries Government Documents Department

The Ridge, the Glasma and Flow

Description: I discuss the ridge phenomena observed in heavy ion collisions at RHIC. I argue that the ridge may be due to flux tubes formed from the Color Glass Condensate in the early Glasma phase of matter produced in such collisions.
Date: September 15, 2008
Creator: McLerran,L.
Partner: UNT Libraries Government Documents Department