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Title: Oak Ridge 25URC Tandem Accelerator 2007 SNEAP Lab Report

Abstract

During FY 2008, the 25URC operated for slightly over 3,000 research hours. The radioactive species 80Ge and 17,18F accounted for 763 of these hours. This included an experiment using 17F which was only possible due to an improvement of a factor of 50 in beam intensity over our previous facility record. Twenty stable beam species were provided this year. Operation for the experimental program was at terminal potentials from 2.02 to 23.8 MV. Approximately 200 hours of conditioning were done to return the machine to operation after tank openings. There were six tank openings during the year: three scheduled for general maintenance and three unscheduled. Two of the unscheduled openings were required to correct shorting rod issues and the other was to reestablish communication with one of the major dead sections. On July 28, an event happened that caused all accelerators at the Holifield Radioactive Ion Beam Facility (HRIBF) to suspend operation. At approximately 8 AM on that Monday, during operations with approximately 12 {micro}A of 50-MeV protons on a uranium carbide target, delivering neutron-rich 81Zn beam to the new Low-energy Radioactive Ion Beam Spectroscopy Station (LeRIBSS), a radiological control technician (RCT) reported higher than normal radiation levels just outsidemore » the shield door to the IRIS1 vault (the room in which RIBs are produced at HRIBF). The measured dose rate equivalent was 4 mrem/hr. The presence of radiological contamination on the floor just outside the shield door was subsequently noted, as was the possible presence of airborne radioactivity. These observations were reported to facility management. Accelerators were put in standby immediately and the building evacuated. The event was declared a laboratory operational emergency. Parts of the building were cleared for reentry to collect belongings on Monday afternoon. The entire building was cleared for reoccupation on Tuesday morning after a detailed radiological survey found no contamination outside the shielded vaults. No decontamination was required. No individual received any detectable radiological dose as a result of this event. The 25URC tandem accelerator was given permission to resume operation with stable beams in early September, but radioactive ion production is still not allowed. Subsequent analysis indicated a release that consisted entirely of noble gasses (Xe and Kr isotopes). We believe we have identified two unrelated failures, one associated with the HVAC system and the other with the roughing system exhaust which accounts for both the escape of noble gasses into the IRIS1 vault and their migration outside the vault. An investigation team report is expected by October 24. At that time, corrective actions will be determined and the path to future radioactive ion beam production will be known. The break from operations allowed a few upgrades to be implemented. The most notable was the installation and commissioning of a SNICS ion source purchased from National Electrostatics Corporation (NEC). The SNICS replaced the old Alton/Aarhus source that we have used for many years. An ANU style gas cathode holder was purchased also but has not yet been implemented. The first beams have been produced by the source and the biggest problem encountered was reducing the beam for very low current experiments. A new power supply for the injection magnet was installed during this period also. Radioactive ion beam (RIB) development at the High Power Target Laboratory (HPTL) has been delayed this year while installing the platforms, conduits and equipment for the second Injector for Radioactive Ion Species (IRIS2) which is co-located with the HPTL facility. The majority of development activities have been performed at the two off-line ion source test facilities (ISTF1 and ISTF2) and the On-Line Test Facility (OLTF). Both test facilities have been developing systems which will eventually be used with IRIS2. Two new tunable Ti:Sapphire lasers have been ordered for continuing development of an ion source based on laser ionization using all solid-state lasers. When these are delivered, we will have a complete laser system. The other ion source test facility is continuing development of a negative-ion cooler for beam purification using photodetachment. This process has been demonstrated to work well in three systems so far (removing Co from Ni, removing S from Cl, and removing O from F). The original ion cooler has been modified to allow for use on the IRIS2 platform. Testing of this modified device is starting now. The OLTF has been used to test new types of uranium carbide targets for the electron beam plasma source (which are used for neutron-rich RIB campaigns) and to test a novel ion source which may result in purified beams of radioactive strontium isotopes. This ion source uses a quartz tube in the transfer line between the production target and the ion source to selectively slow down some elements such as rubidium and cesium.« less

Authors:
 [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Holifield Radioactive Ion Beam Facility (HRIBF)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1024643
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: Symposium of North Eastern Accelerator Personnel 2007, Provo, UT, USA, 20071007, 20071012
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCELERATORS; DOSE RATES; ELECTRON BEAMS; ELECTROSTATICS; HEAT EXCHANGERS; HVAC SYSTEMS; ION SOURCES; IONIZATION; OPENINGS; PERSONNEL; PRODUCTION; PURIFICATION; RADIOACTIVE ION BEAMS; SHIELDS; SPECTROSCOPY; STRONTIUM ISOTOPES; TEST FACILITIES; URANIUM CARBIDES

Citation Formats

Meigs, Martha J, and Juras, Raymond C. Oak Ridge 25URC Tandem Accelerator 2007 SNEAP Lab Report. United States: N. p., 2008. Web.
Meigs, Martha J, & Juras, Raymond C. Oak Ridge 25URC Tandem Accelerator 2007 SNEAP Lab Report. United States.
Meigs, Martha J, and Juras, Raymond C. 2008. "Oak Ridge 25URC Tandem Accelerator 2007 SNEAP Lab Report". United States.
@article{osti_1024643,
title = {Oak Ridge 25URC Tandem Accelerator 2007 SNEAP Lab Report},
author = {Meigs, Martha J and Juras, Raymond C},
abstractNote = {During FY 2008, the 25URC operated for slightly over 3,000 research hours. The radioactive species 80Ge and 17,18F accounted for 763 of these hours. This included an experiment using 17F which was only possible due to an improvement of a factor of 50 in beam intensity over our previous facility record. Twenty stable beam species were provided this year. Operation for the experimental program was at terminal potentials from 2.02 to 23.8 MV. Approximately 200 hours of conditioning were done to return the machine to operation after tank openings. There were six tank openings during the year: three scheduled for general maintenance and three unscheduled. Two of the unscheduled openings were required to correct shorting rod issues and the other was to reestablish communication with one of the major dead sections. On July 28, an event happened that caused all accelerators at the Holifield Radioactive Ion Beam Facility (HRIBF) to suspend operation. At approximately 8 AM on that Monday, during operations with approximately 12 {micro}A of 50-MeV protons on a uranium carbide target, delivering neutron-rich 81Zn beam to the new Low-energy Radioactive Ion Beam Spectroscopy Station (LeRIBSS), a radiological control technician (RCT) reported higher than normal radiation levels just outside the shield door to the IRIS1 vault (the room in which RIBs are produced at HRIBF). The measured dose rate equivalent was 4 mrem/hr. The presence of radiological contamination on the floor just outside the shield door was subsequently noted, as was the possible presence of airborne radioactivity. These observations were reported to facility management. Accelerators were put in standby immediately and the building evacuated. The event was declared a laboratory operational emergency. Parts of the building were cleared for reentry to collect belongings on Monday afternoon. The entire building was cleared for reoccupation on Tuesday morning after a detailed radiological survey found no contamination outside the shielded vaults. No decontamination was required. No individual received any detectable radiological dose as a result of this event. The 25URC tandem accelerator was given permission to resume operation with stable beams in early September, but radioactive ion production is still not allowed. Subsequent analysis indicated a release that consisted entirely of noble gasses (Xe and Kr isotopes). We believe we have identified two unrelated failures, one associated with the HVAC system and the other with the roughing system exhaust which accounts for both the escape of noble gasses into the IRIS1 vault and their migration outside the vault. An investigation team report is expected by October 24. At that time, corrective actions will be determined and the path to future radioactive ion beam production will be known. The break from operations allowed a few upgrades to be implemented. The most notable was the installation and commissioning of a SNICS ion source purchased from National Electrostatics Corporation (NEC). The SNICS replaced the old Alton/Aarhus source that we have used for many years. An ANU style gas cathode holder was purchased also but has not yet been implemented. The first beams have been produced by the source and the biggest problem encountered was reducing the beam for very low current experiments. A new power supply for the injection magnet was installed during this period also. Radioactive ion beam (RIB) development at the High Power Target Laboratory (HPTL) has been delayed this year while installing the platforms, conduits and equipment for the second Injector for Radioactive Ion Species (IRIS2) which is co-located with the HPTL facility. The majority of development activities have been performed at the two off-line ion source test facilities (ISTF1 and ISTF2) and the On-Line Test Facility (OLTF). Both test facilities have been developing systems which will eventually be used with IRIS2. Two new tunable Ti:Sapphire lasers have been ordered for continuing development of an ion source based on laser ionization using all solid-state lasers. When these are delivered, we will have a complete laser system. The other ion source test facility is continuing development of a negative-ion cooler for beam purification using photodetachment. This process has been demonstrated to work well in three systems so far (removing Co from Ni, removing S from Cl, and removing O from F). The original ion cooler has been modified to allow for use on the IRIS2 platform. Testing of this modified device is starting now. The OLTF has been used to test new types of uranium carbide targets for the electron beam plasma source (which are used for neutron-rich RIB campaigns) and to test a novel ion source which may result in purified beams of radioactive strontium isotopes. This ion source uses a quartz tube in the transfer line between the production target and the ion source to selectively slow down some elements such as rubidium and cesium.},
doi = {},
url = {https://www.osti.gov/biblio/1024643}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Jan 01 00:00:00 EST 2008},
month = {Tue Jan 01 00:00:00 EST 2008}
}

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