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Title: SNS TARGET BEAM PROFILE VIEWSCREEN DESIGN AND OPERATION

Abstract

A phosphor screen was installed in front of the Spallation Neutron Source (SNS) mercury target to monitor the proton beam profile for initial commissioning in April, 2006. The viewscreen was used to center the beam on the target, monitor and adjust beam profile to fit within the nominal 70mm x 200mm footprint on the target and to calibrate upstream beam diagnostics. The system was originally intended for commissioning at very low power. It was found to be a very useful diagnostic and removal was postponed until thermal limits at 10 kW were reached. This paper will discuss the optical and mechanical design of the system and results. Options for adding a similar system in the future to SNS will also be discussed.

Authors:
 [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
982716
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: The Eighth International Topical Meeting on Nuclear Applications and Utilization of Accelerators, Pocatello, ID, USA, 20070730, 20070802
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCELERATORS; BEAM PROFILES; COMMISSIONING; DESIGN; MERCURY; MONITORS; NEUTRON SOURCES; PHOSPHORS; PROTON BEAMS; REMOVAL; SCREENS; SPALLATION; TARGETS; instrumentation; accelerators; imaging; targets; neutrons

Citation Formats

Shea, Thomas J, Goetz, Kathleen C, and McManamy, Thomas J. SNS TARGET BEAM PROFILE VIEWSCREEN DESIGN AND OPERATION. United States: N. p., 2007. Web.
Shea, Thomas J, Goetz, Kathleen C, & McManamy, Thomas J. SNS TARGET BEAM PROFILE VIEWSCREEN DESIGN AND OPERATION. United States.
Shea, Thomas J, Goetz, Kathleen C, and McManamy, Thomas J. Mon . "SNS TARGET BEAM PROFILE VIEWSCREEN DESIGN AND OPERATION". United States. doi:.
@article{osti_982716,
title = {SNS TARGET BEAM PROFILE VIEWSCREEN DESIGN AND OPERATION},
author = {Shea, Thomas J and Goetz, Kathleen C and McManamy, Thomas J},
abstractNote = {A phosphor screen was installed in front of the Spallation Neutron Source (SNS) mercury target to monitor the proton beam profile for initial commissioning in April, 2006. The viewscreen was used to center the beam on the target, monitor and adjust beam profile to fit within the nominal 70mm x 200mm footprint on the target and to calibrate upstream beam diagnostics. The system was originally intended for commissioning at very low power. It was found to be a very useful diagnostic and removal was postponed until thermal limits at 10 kW were reached. This paper will discuss the optical and mechanical design of the system and results. Options for adding a similar system in the future to SNS will also be discussed.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
Other availability
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  • The Spallation Neutron Source (SNS) construction project has been completed including initial beam operation with the mercury target, moderators and associated systems. The project was initiated in 1999, with groundbreaking in December of 1999. Final integrated system testing for the mercury target, cryogenic moderators, shutter systems, water and other utility systems and all control and safety systems were completed in April 2006 and first beam on target delivered April 28, 2006. This paper will give an overview of the system testing conducted in preparation for beam operation and initial operating experience with low power beams. One area of testing wasmore » extensive remote handling testing in the Target Service Bay to demonstrate all key operations associated with the target and mercury loop. Many improvements were implemented as a result of this experience. Another set of tests involved bringing the supercritical cryogenic moderator systems on line. Again, lesions learned here resulted in system changes. Testing of the four water loops was very time consuming because of the complexity of the systems and many instrumentation issues had to be resolved. A temporary phosphor view screen was installed on the front of the target which has been extremely useful in evaluating the beam profile on the target. Initial profile results will be presented. Target System performance for initial beam operation will be discussed. In general, all systems performed well with excellent availability. There were some unexpected findings. For example, xenon spallation gas products are believed to have deposited on a downstream gold amalgamation bed designed to remove mercury vapor and increased the local dose rate. A summary of findings and plans for ramping up in power will be given.« less
  • A detailed radiation transport analysis of the Spallation Neutron Source (SNS) shutters is important for the construction of the SNS because of its impact on conventional facility design, normal operation of the facility, and maintenance operations. Thus far the analysis of the SNS shutter travel gaps has been completed. This analysis was performed using coupled Monte Carlo and multi-dimensional discrete ordinates calculations.
  • After several years of operation, the SNS now enters an era of megawatt class operation. At this intensity level, the target will be operating closer to its engineering limits and the beam profile on target must be carefully controlled. During commissioning and early operations, a temporary imaging system was used to measure the proton density on target. This system was not designed to survive the increasing power levels and it had to be removed in the second half of 2006. Since then, no direct measurement of beam properties at the target has been available. A collaboration was forged to remedymore » this situation, and has resulted in a new imaging system consisting of three major components: a thermal-sprayed luminescent coating deposited on the target nose, a radiation-tolerant optical system installed upstream of the target, and an image acquisition system integrated with the accelerator controls network. The design, installation, and integration of these components will be described. Initial beam measurements and image analysis results will be presented. Lessons learned during this initial operating experience have been documented and will guide the collaboration s future plans.« less
  • A beam profile monitor for H-beams based on laser photoneutralization is being developed at Brookhaven National Laboratory (BNL) for use on the Spallation Neutron Source (SNS) [l]. An H ion has a first ionization potential of 0.75eV and can be neutralized by light from a Nd:YAG laser (h=1064nm). To measure beam profiles, a narrow laser beam is passed through the ion beam neutralizing a portion of the H-beam struck by the laser. The laser trajectory is stepped across the ion beam. At each laser position, the reduction of the beam current caused by the laser is measured. A proof-of-principle experimentmore » was done earlier at 750keV. This paper reports on measurements made on 200MeV beam at BNL and with a compact scanner prototype at Lawrence Berkeley National Lab on beam from the SNS RFQ.« less
  • A beam profile monitor for H{sup -} beams using laser photoneutralization is being developed at Brookhaven National Laboratory [1] for use on the Spallation Neutron Source (SNS) [2]. An H{sup -} ion has a first ionization potential of 0.75eV and can be neutralized by light from a Nd:YAG laser ({lambda}=1064nm). To measure beam profiles, a narrow laser beam is passed through the ion beam neutralizing a portion of the H{sup -} beam struck by the laser, and the perturbation of the beam current caused by the laser is measured. The laser trajectory is stepped across the ion beam generating amore » transverse profile. Proof-of-principle experiments were done at 750keV and 200MeV. Also a compact scanner prototype was used at Lawrence Berkeley National Laboratory (LBNL) [3] during commissioning of the SNS RFQ.« less