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RHIC Performance as a 100 GeV Polarized Proton Collider in Run-9 (open access)

RHIC Performance as a 100 GeV Polarized Proton Collider in Run-9

During the second half of Run-9, the Relativisitc Heavy Ion Collider (RHIC) provided polarized proton collisions at two interaction points. The spin orientation of both beams at these collision points was controlled by helical spin rotators, and physics data were taken with different orientations of the beam polarization. Recent developments and improvements will be presented, as well as luminosity and polarization performance achieved during Run-9.
Date: May 23, 2010
Creator: Montag, C.; Ahrens, L.; Bai, M.; Beebe-Wang, J.; Blaskiewicz, M.; Brennan, J. M. et al.
System: The UNT Digital Library
Transcriptomic response of the mycoparasitic fungus Trichoderma atroviride to the presence of a fungal prey (open access)

Transcriptomic response of the mycoparasitic fungus Trichoderma atroviride to the presence of a fungal prey

BACKGROUND: Combating the action of plant pathogenic microorganisms by mycoparasitic fungi has been announced as an attractive biological alternative to the use of chemical fungicides since two decades. The fungal genus Trichoderma includes a high number of taxa which are able to recognize, combat and finally besiege and kill their prey. Only fragments of the biochemical processes related to this ability have been uncovered so far, however. RESULTS: We analyzed genome-wide gene expression changes during the begin of physical contact between Trichoderma atroviride and two plant pathogens Botrytis cinerea and Rhizoctonia solani, and compared with gene expression patterns of mycelial and conidiating cultures, respectively. About 3000 ESTs, representing about 900 genes, were obtained from each of these three growth conditions. 66 genes, represented by 442 ESTs, were specifically and significantly overexpressed during onset of mycoparasitism, and the expression of a subset thereof was verified by expression analysis. The upregulated genes comprised 18 KOG groups, but were most abundant from the groups representing posttranslational processing, and amino acid metabolism, and included components of the stress response, reaction to nitrogen shortage, signal transduction and lipid catabolism. Metabolic network analysis confirmed the upregulation of the genes for amino acid biosynthesis and of those …
Date: July 23, 2010
Creator: Seidl, Verena; Song, Lifu; Lindquist, Erika; Gruber, Sabine; Koptchinskiy, Alexeji; Zeilinger, Susanne et al.
System: The UNT Digital Library
Update on the Innovative Carbon/Proton Non-Scaling FFAG Isocentric gantries for Cancer Therapy (open access)

Update on the Innovative Carbon/Proton Non-Scaling FFAG Isocentric gantries for Cancer Therapy

There is a dramatic increase in numbers of proton/carbon cancer therapy facilities in recent years due to a clear advantage with respect to the other radiation therapy treatments. Cost of the ion cancer therapy is still to high for most of the hospitals and a dominating part comes from the delivery systems. We had previously presented design of the carbon and proton isocentric gantries using the principle of the non-scaling alternating gradient fixed field magnets (NS-FFAG), where a size and weight of the magnets should be dramatically reduced. The weight of the transport elements of the carbon isocentric gantry is estimated to be 1.5 tons compared to the 130 tons a weight of the Heidelberg gantry. The similar claim of 500 kg comes for the transport elements of the proton permanent magnet gantry. We present an update on these designs.
Date: May 23, 2010
Creator: Trbojevic, D.
System: The UNT Digital Library
High Precision Tune and Coupling Feedback and Beam Transfer Function Measurements in RHIC (open access)

High Precision Tune and Coupling Feedback and Beam Transfer Function Measurements in RHIC

Precision measurement and control of the betatron tunes and betatron coupling in the Relativistic Heavy Ion Collider (RHIC) are required for establishing and maintaining both good operating conditions and, particularly during the ramp to high beam energies, high proton beam polarization. While the proof-of-principle for simultaneous tune and coupling feedback was successfully demonstrated earlier, routine application of these systems has only become possible recently. Following numerous modifications for improved measurement resolution and feedback control, the time required to establish full-energy beams with the betatron tunes and coupling regulated by feedback was reduced from several weeks to a few hours. A summary of these improvements, select measurements benefitting from the improved resolution and a review of system performance are the subject of this report.
Date: May 23, 2010
Creator: Minty, M.; Curcio, A.; Dawson, C.; Degen, C.; Luo, Y.; Marr, G. et al.
System: The UNT Digital Library
Normal Conducting RF Cavity for MICE (open access)

Normal Conducting RF Cavity for MICE

Normal conducting RF cavities must be used for the cooling section of the international Muon Ionization Cooling Experiment (MICE), currently under construction at Rutherford Appleton Laboratory (RAL) in the UK. Eight 201-MHz cavities are needed for the MICE cooling section; fabrication of the first five cavities is complete. We report the cavity fabrication status including cavity design, fabrication techniques and preliminary low power RF measurements.
Date: May 23, 2010
Creator: Li, D.; DeMello, A.; Virostek, S.; Zisman, M. & Summers, D.
System: The UNT Digital Library
Chemical Imaging of the Cell Membrane by NanoSIMS (open access)

Chemical Imaging of the Cell Membrane by NanoSIMS

The existence of lipid microdomains and their role in cell membrane organization are currently topics of great interest and controversy. The cell membrane is composed of a lipid bilayer with embedded proteins that can flow along the two-dimensional surface defined by the membrane. Microdomains, known as lipid rafts, are believed to play a central role in organizing this fluid system, enabling the cell membrane to carry out essential cellular processes, including protein recruitment and signal transduction. Lipid rafts are also implicated in cell invasion by pathogens, as in the case of the HIV. Therefore, understanding the role of lipid rafts in cell membrane organization not only has broad scientific implications, but also has practical implications for medical therapies. One of the major limitations on lipid organization research has been the inability to directly analyze lipid composition without introducing artifacts and at the relevant length-scales of tens to hundreds of nanometers. Fluorescence microscopy is widely used due to its sensitivity and specificity to the labeled species, but only the labeled components can be observed, fluorophores can alter the behavior of the lipids they label, and the length scales relevant to imaging cell membrane domains are between that probed by fluorescence resonance …
Date: February 23, 2010
Creator: Weber, P K; Kraft, M L; Frisz, J F; Carpenter, K J & Hutcheon, I D
System: The UNT Digital Library
Microbunching Instability Effect Studies and Laser Heater Optimization for the SPARX FEL Accelerator (open access)

Microbunching Instability Effect Studies and Laser Heater Optimization for the SPARX FEL Accelerator

The effects of microbunching instability for the SPARX accelerator have been analyzed by means of numerical simulations. The laser heater counteracting action has been addressed in order to optimize the parameters of the compression system, either hybrid RF plus magnetic chicane or only magnetic, and possibly enhance the FEL performance.
Date: May 23, 2010
Creator: Vaccarezza, C.; Chiadroni, E.; Ferrario, M.; Giannessi, L.; Quattromini, M.; Ronsivalle, C. et al.
System: The UNT Digital Library
STATUS OF THE RHIC HEAD-ON BEAM-BEAM COMPENSATION PROJECT (open access)

STATUS OF THE RHIC HEAD-ON BEAM-BEAM COMPENSATION PROJECT

In polarized proton operation the luminosity of RHIC is limited by the head-on beam-beam effect, and methods that mitigate the effect will result in higher peak and average luminosities. Two electron lenses, one for each ring, are being constructed to partially compensate the head-on beam-beam effect in the two rings. An electron lens consists of a low energy electron beam that creates the same amplitude dependent transverse kick as the proton beam. We discuss design considerations and present the main parameters.
Date: May 23, 2010
Creator: Fischer, W.; Luo, Y.; Pikin, A.; Beebe, E.; Bruno, D.; Gassner, D. et al.
System: The UNT Digital Library
NanoSIMS analysis of Bacillus spores for forensics (open access)

NanoSIMS analysis of Bacillus spores for forensics

The threat associated with the potential use of radiological, nuclear, chemical and biological materials in terrorist acts has resulted in new fields of forensic science requiring the application of state-of-the-science analytical techniques. Since the anthrax letter attacks in the United States in the fall of 2001, there has been increased interest in physical and chemical characterization of bacterial spores. While molecular methods are powerful tools for identifying genetic differences, other methods may be able to differentiate genetically identical samples based on physical and chemical properties, as well as provide complimentary information, such as methods of production and approximate date of production. Microanalysis has the potential to contribute significantly to microbial forensics. Bacillus spores are highly structured, consisting of a core, cortex, coat, and in some species, an exosporium. This structure provides a template for constraining elemental abundance differences at the nanometer scale. The primary controls on the distribution of major elements in spores are likely structural and physiological. For example, P and Ca are known to be abundant in the spore core because that is where P-rich nucleic acids and Cadipicolinic acid are located, respectively. Trace elements are known to bind to the spore coat but the controls on these …
Date: February 23, 2010
Creator: Weber, P K; Davisson, M L & Velsko, S P
System: The UNT Digital Library
Experience with split transition lattices at RHIC (open access)

Experience with split transition lattices at RHIC

During the acceleration process, heavy ion beams in RHIC cross the transition energy. When RHIC was colliding deuterons and gold ions during Run-8, lattices with different integer tunes were used for the two rings. This resulted in the two rings crossing transition at different times, which proved beneficial for the 'Yellow' ring, the RF system of which is slaved to the 'Blue' ring. For the symmetric gold-gold run in FY2010, lattices with different transition energies but equal tunes were implemented. We report the optics design concept as well as operational experience with this configuration.
Date: May 23, 2010
Creator: Montag, C.; Tepikian, S.; Blaskiewicz, M. & Brennan, J. M.
System: The UNT Digital Library
LIS in low power density for RHIC-EBIS (open access)

LIS in low power density for RHIC-EBIS

The Electron Beam Ion Source (EBIS) project at Brookhaven National Laboratory is a new heavy ion preinjector for Relativistic Heavy Ion Collider (RHIC) and NASA Space Radiation Laboratory science programs. Laser Ion Source (LIS), which can supply many heavy ion species using solid targets, is a candidate of a primary ion source provider for RHIC-EBIS. LIS experiment with 5 Hz operation, which is required practically in RHIC-EBIS, was demonstrated to understand the beam property for long operation time. High laser power density decayed the peak current and ion yield with operation time and did not keep the surface of target flat. On the contrary, the beam in low laser power density kept the performance in long operation time.
Date: May 23, 2010
Creator: Kondo, K.; Kanesue, T.; Dabrowski, R. & Okamura, M.
System: The UNT Digital Library
Magnet design of the ENC@FAIR interaction region (open access)

Magnet design of the ENC@FAIR interaction region

The Electron Nucleon Collider, proposed as an extension to the High Energy Storage Ring (HESR), is currently investigated and a first layout of the Interaction Region (IR) proposed. The limited size of the machine, the low beam energy and the Lorentz force vector pointing in the same direction for both beams make the IR design demanding. In this paper we present the parameters of the IR magnets, show the boundary conditions given by the beam dynamics and the experiments. We present first 2D designs for the electron and proton triplet magnets along with the separating dipole next to the collision point. Different methods to shield the beam in the spectrometer dipoles are investigated and presented.
Date: May 23, 2010
Creator: Schnizer, P.; Montag, C.; Aulenbacher, K.; Jankowiak, A. & Ludwig-Mertin, U.
System: The UNT Digital Library
Diboson Production at the Tevatron (open access)

Diboson Production at the Tevatron

Here we summarize the recent measurements of the diboson production cross sections and limits on trilinear gauge boson couplings using 1-5 fb{sup -1} of Tevatron data collected by the CDF and D0 detectors. These results are the most precise to date from a hadron collider.
Date: July 23, 2010
Creator: Sekaric, Jadranka
System: The UNT Digital Library
Generating Ultrashort Coherent Soft X-ray Radiation in Storage Rings Using Angular-modulated Electron Beams (open access)

Generating Ultrashort Coherent Soft X-ray Radiation in Storage Rings Using Angular-modulated Electron Beams

A technique is proposed to generate ultrashort coherent soft x-ray radiation in storage rings using angular-modulated electron beams. In the scheme a laser operating in the TEM01 mode is first used to modulate the angular distribution of the electron beam in an undulator. After passing through a special beam line with non-zero transfer matrix element R{sub 54}, the angular modulation is converted to density modulation which contains considerable higher harmonic contents of the laser. It is found that the harmonic number can be one or two orders of magnitude higher than the standard coherent harmonic generation method which relies on beam energy modulation. The technique has the potential of generating femtosecond coherent soft x-ray radiation directly from an infrared seed laser and may open new research opportunities for ultrafast sciences in storage rings.
Date: August 23, 2010
Creator: Xiang, D. & Wan, W.
System: The UNT Digital Library
A 3-dimensional theory of free electron lasers (open access)

A 3-dimensional theory of free electron lasers

In this paper, we present an analytical three-dimensional theory of free electron lasers. Under several assumptions, we arrive at an integral equation similar to earlier work carried out by Ching, Kim and Xie, but using a formulation better suited for the initial value problem of Coherent Electron Cooling. We use this model in later papers to obtain analytical results for gain guiding, as well as to develop a complete model of Coherent Electron Cooling.
Date: August 23, 2010
Creator: Webb, S. D.; Wang, G. & Litvinenko, V. N.
System: The UNT Digital Library
DPIS for warm dense matter (open access)

DPIS for warm dense matter

Warm Dense Matter (WDM) offers an challenging problem because WDM, which is beyond ideal plasma, is in a low temperature and high density state with partially degenerate electrons and coupled ions. WDM is a common state of matter in astrophysical objects such as cores of giant planets and white dwarfs. The WDM studies require large energy deposition into a small target volume in a shorter time than the hydrodynamical time and need uniformity across the full thickness of the target. Since moderate energy ion beams ({approx} 0.3 MeV/u) can be useful tool for WDM physics, we propose WDM generation using Direct Plasma Injection Scheme (DPIS). In the DPIS, laser ion source is connected to the Radio Frequency Quadrupole (RFQ) linear accelerator directly without the beam transport line. DPIS with a realistic final focus and a linear accelerator can produce WDM.
Date: May 23, 2010
Creator: Kondo, K.; Kanesue, T.; Horioka, K. & Okamura, M.
System: The UNT Digital Library
Spin dynamics simulations at AGS (open access)

Spin dynamics simulations at AGS

To preserve proton polarization through acceleration, it is important to have a correct model of the process. It has been known that with the insertion of the two helical partial Siberian snakes in the Alternating Gradient Synchrotron (AGS), the MAD model of AGS can not deal with a field map with offset orbit. The stepwise ray-tracing code Zgoubi provides a tool to represent the real electromagnetic fields in the modeling of the optics and spin dynamics for the AGS. Numerical experiments of resonance crossing, including spin dynamics in presence of the snakes and Q-jump, have been performed in AGS lattice models, using Zgoubi. This contribution reports on various results so obtained.
Date: May 23, 2010
Creator: Huang, H.; MacKay, W. W.; Meot, F. & Roser, T.
System: The UNT Digital Library
RHIC PROTON BEAM LIFETIME INCREASE WITH 10- AND 12-POLE CORRECTORS (open access)

RHIC PROTON BEAM LIFETIME INCREASE WITH 10- AND 12-POLE CORRECTORS

The RHIC beam lifetime in polarized proton operation is dominated by the beam-beam effect, parameter modulations, and nonlinear magnet errors in the interaction region magnets. Sextupole and skew sextupole errors have been corrected deterministically for a number of years based on tune shift measurements with orbit bumps in the triplets. During the most recent polarized proton run 10- and 12- pole correctors were set through an iterative procedure, and used for the first time operationally in one of the beams. We report on the procedure to set these high-order multipole correctors and estimate their effect on the integrated luminosity.
Date: May 23, 2010
Creator: Fischer, W.
System: The UNT Digital Library
Measurements of Fast Transition Instability in RHIC (open access)

Measurements of Fast Transition Instability in RHIC

A fast transition instability presents a limiting factor for ion beam intensity in RHIC. Several pieces of evidence show that electron clouds play an important role in establishing the threshold of this instability. In RHIC Runs8 the measurements of the instability, using a button BPM, were done in order to observe details of the instability development on the scale over hundreds and thousands turns. The paper presents and discusses the results of those measurements in time and frequency domains.
Date: May 23, 2010
Creator: Ptitsyn, V.; Blaskiewicz, M.; Fischer, W.; Lee, R. & Zhang, S. Y.
System: The UNT Digital Library
RHIC Performance During the FY10 200 GeV Au+Au Heavy Ion Run (open access)

RHIC Performance During the FY10 200 GeV Au+Au Heavy Ion Run

Since the last successful RHIC Au+Au run in 2007 (Run-7), the RHIC experiments have made numerous detector improvements and upgrades. In order to benefit from the enhanced detector capabilities and to increase the yield of rare events in the acquired heavy ion data a significant increase in luminosity is essential. In Run-7 RHIC achieved an average store luminosity of <L> = 12 x 10{sup 26} cm{sup -2} s{sup -1} by operating with 103 bunches (out of 111 possible), and by squeezing to {beta}* = 0.85 m. This year, Run-10, we achieved <L> = 20 x 10{sup 26} cm{sup -2} s{sup -1}, which put us an order of magnitude above the RHIC design luminosity. To reach these luminosity levels we decreased {beta}* to 0.75 m, operated with 111 bunches per ring, and reduced longitudinal and transverse emittances by means of bunched-beam stochastic cooling. In addition we introduced a lattice to suppress intra-beam scattering (IBS) in both RHIC rings, upgraded the RF control system, and separated transition crossing times in the two rings. We present an overview of the changes and the results of Run-10 performance.
Date: May 23, 2010
Creator: Brown, K. A.; Ahrens, L.; Bai, M.; Beebe-Wang, J.; Blaskiewicz, M.; Brennan, J. et al.
System: The UNT Digital Library
E-Cloud Drivent Single-Bunch Instabilities in PS2 (open access)

E-Cloud Drivent Single-Bunch Instabilities in PS2

One of the proposals under consideration for future upgrades of the LHC injector complex entails the replacement of the PS with the PS2, a longer circumference and higher energy synchrotron, with electron cloud effects representing a potentially serious limitation to the achievement of the upgrade goals. We report on ongoing numerical studies aiming at estimating the e-cloud density threshold for the occurrence of single bunch instabilities.
Date: May 23, 2010
Creator: Venturini, M.; Furman, M.; Penn, G.; Secondo, R.; Vay, J. L.; De Maria, R. et al.
System: The UNT Digital Library
The Carboxysome and Other Bacterial Microcompartments (open access)

The Carboxysome and Other Bacterial Microcompartments

- Carboxysomes are part of the carbon concentrating mechanism in cyanobacteria and chemoautotrophs. - Carboxysomes are a subclass of bacterial microcompartments (BMCs); BMCs can encapsulate a range of metabolic processes. - Like some viral particles, the carboxysome can be modeled as an icosahedron-in its case, having 4,000-5,000 hexameric shell subunits and 12 surface pentamers to generate curvature. - The threefold axis of symmetry of the CsoS1D protein in carboxysomes forms a pore that can open and close, allowing for selective diffusion. - Genetic modules encoding BMC shell proteins and the enzymes that they encapsulate are horizontally transferable, suggesting they enable bacteria to adapt to diverse environments.
Date: June 23, 2010
Creator: Kerfeld, Cheryl A.; Greenleaf, William B. & Kinney, James N.
System: The UNT Digital Library
Lattice design for the ERL electron ion collider in RHIC (open access)

Lattice design for the ERL electron ion collider in RHIC

We present electron ion collider lattice design for the Relativistic Heavy Ion Collider (eRHIC) where the electrons have multi-passes through recirculating linacs (ERL) and arcs placed in the existing RHIC tunnel. The present RHIC interaction regions (IR's), where the electron ion collisions will occur, are modified to allow for the large luminosity. Staging of eRHIC will bring the electron energy from 4 up to 20 (30) GeV as the superconducting cavities are built and installed sequentially. The synchrotron radiation from electrons at the IR is reduced as they arrive straight to the collision while ions and protons come with 10 mrad crossing angle using the crab cavities.
Date: May 23, 2010
Creator: Trbojevic, D.; Beebe-Wang, J.; Tsoupas, N.; Chang, X.; Kayran, D.; Ptitsyn, V. et al.
System: The UNT Digital Library
Signal quality of the LHC AC dipoles and its impact on beam dynamics (open access)

Signal quality of the LHC AC dipoles and its impact on beam dynamics

The adiabaticity of the AC dipole might be compromised by noise or unwanted frequency components in its signal. An effort has been put to characterize and optimize the signal quality of the LHC AC dipoles. The measured signal is used in realistic simulations in order to evaluate its impact on beam dynamics and to ultimately establish safe margins for the operation of the LHC AC dipoles.
Date: May 23, 2010
Creator: Miyamoto, R.; Cattin, M.; Serrano, J. & Tomas, R.
System: The UNT Digital Library