171 research outputs found
R&D ERL: High power RF systems
The Energy Recovery Linac (ERL) project, now under construction at Brookhaven National Laboratory, requires two high power RF systems. The first RF system is for the 703.75 MHz superconducting electron gun. The RF power from this system is used to drive nearly half an Ampere of beam current to 2.5 MeV. There is no provision to recover any of this energy so the minimum amplifier power is 1 MW. It consists of 1 MW CW klystron, transmitter and power supplies, 1 MW circulator, 1 MW dummy load and a two-way power splitter. The second RF system is for the 703.75 MHz superconducting cavity. The system accelerates the beam to 54.7 MeV and recovers this energy. It will provide up to 50 kW of CW RF power to the cavity. It consists of 50 kW transmitter, circulator, and dummy load. This paper describes the two high power RF systems and presents the test data for both
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High power RF systems for the BNL ERL project
The Energy Recovery Linac (ERL) project, now under construction at Brookhaven National Laboratory, requires two high power RF systems. The first RF system is for the 703.75 MHz superconducting electron gun. The RF power from this system is used to drive nearly half an Ampere of beam current to 2 MeV. There is no provision to recover any of this energy so the minimum amplifier power is 1 MW. It consists of 1 MW CW klystron, transmitter and power supplies, 1 MW circulator, 1 MW dummy load and a two-way power splitter. The second RF system is for the 703.75 MHz superconducting cavity. The system accelerates the beam to 54.7 MeV and recovers this energy. It will provide up to 50 kW of CW RF power to the cavity. It consists of 50 kW transmitter, circulator, and dummy load. This paper describes the two high power RF systems and presents the test data for both
Estrogen-Receptor Expression and Function in Thymocytes in Relation to Gender and Age
The expression of estrogen receptor (ER) in thymocytes was studied in young, middle-aged, and
old (2, 12, and 24 months, respectively) female and male C57BL/6J mice. Western immunoblots
prepared from the thymocytes of females of all age groups showed the presence of a 67-kD
protein band, which has been associated with the apparent MW of denatured ER. Flow cytometry
analysis o,f cells stained with a monoclonal anti-ER antibody (clone 13H2) disclosed ER
expression in both females and males of all age groups. In vivo treatment with estradiol (E2) led
to an increase in the specific activity of thymic creatine kinase (CK) in the female mice, whereas
the male thymocytes responded with an increase in CK activity only on treatment with
dihydrotestosterone (DHT). The data show no differences in ER expression between male and
females, but the receptor appears not to be functional in males. Interestingly, when estradiol was
applied to co-cultures of lymphoid-depleted fetal thymus (FT) explants and bone-marrow cells,
or thymocytes, from young and old females, it resulted in increased cellularity of cultures
containing cells of the young, and not those of the old. The proportion of CD4/CD8 phenotypes
of the developing cells in these cultures was not affected by E2 treatment. These observations
provide a new insight into ER expression and function in T-cell development in relation to
gender and age
Higher order mode damper for low energy RHIC electron cooler SRF booster cavity
To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon,
the Low Energy RHIC electron Cooler (LEReC) is currently under commissioning at
BNL. The Linac of LEReC is designed to deliver a 1.6 MeV to 2.6 MeV electron
beam, with rms dp/p less than 5e-4. A 704 MHz superconducting radio frequency
(SRF) booster cavity in this Linac provides up to 2.2 MeV accelerating voltage.
With such a low energy and very demanding energy spread requirement, control of
Higher Order Modes (HOMs) in the cavities becomes critical and needs to be
carefully evaluated to ensure minimum impact on the beam. In this paper, we
report the multiphysics design of the HOM damper for this cavity to meet the
energy spread requirement, as well as experimental results of the cavity with
and without the HOM damper.Comment: 9 pages, 7 figure
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Commissioning results from the recently upgraded RHIC LLRF system
During RHIC Run 10, the first phase of the LLRF Upgrade was successfully completed. This involved replacing the aging VME based system with a modern digital system based on the recently developed RHIC LLRF Upgrade Platform, and commissioning the system as part of the normal RHIC start up process. At the start of Run 11, the second phase of the upgrade is underway, involving a significant expansion of both hardware and functionality. This paper will review the commissioning effort and provide examples of improvements in system performance, flexibility and scalability afforded by the new platform. The RHIC LLRF upgrade is based on the recently developed RHIC LLRF Upgrade Platform. The major design goals of the platform are: (1) Design a stand alone, generic, digital, modular control architecture which can be configured to satisfy all of the application demands we currently have, and which will be supportable and upgradeable into the foreseeable future; and (2) It should integrate seamlessly into existing controls infrastructure, be easy to deploy, provide access to all relevant control parameters (eliminate knobs), provide vastly improved diagnostic data capabilities, and permit remote reconfiguration. Although the system is still in its infancy, we think the initial commissioning results from RHIC indicate that these goals have been achieved, and that we've only begun to realize the benefits the platform provides
Interlayer Registry Determines the Sliding Potential of Layered Metal Dichalcogenides: The case of 2H-MoS2
We provide a simple and intuitive explanation for the interlayer sliding
energy landscape of metal dichalcogenides. Based on the recently introduced
registry index (RI) concept, we define a purely geometrical parameter which
quantifies the degree of interlayer commensurability in the layered phase of
molybdenum disulphide (2HMoS2). A direct relation between the sliding energy
landscape and the corresponding interlayer registry surface of 2H-MoS2 is
discovered thus marking the registry index as a computationally efficient means
for studying the tribology of complex nanoscale material interfaces in the
wearless friction regime.Comment: 13 pages, 7 figure
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