Accelerator Radiation Safety Newsletter
Official Publication of the Health Physics Society
From the Officers
President Elects Message
It’s hard to believe, but the annual meeting of the Health
Physics Society (HPS) is just two months away. If you’ll be attending the
The executive board of the section will meet on Monday
evening, July 13. For officers and directors of the section who are attending
Early the next morning on Tuesday, July 14, at 8:30 AM we will convene the 2009 Accelerator Section Special Session. While we were unsuccessful in our bid for a Morgan lectureship this year, we are fortunate to have an all-star cast of speakers for our special session. On Tuesday morning, these luminaries will include Nolan Hertel, Michael Shannon, and Eric Burgett from Georgia Tech; Pavel Degtiarenko and Vashek Vylet from Jefferson Lab; Reg Ronningen from Michigan State; Mike Sandvig from Idaho National Lab; Mike Duran from Los Alamos National Lab; and Steve Butala from Argonne National Lab.
We’ll take a break at 11:15 AM on Tuesday morning to convene the Accelerator Section Business Meeting. I encourage all of you who have enjoyed the morning talks to join the section members as we wrap up the elections for next year’s executive board of directors and discuss other section business. This is a great opportunity for section members to voice their opinions on how the Accelerator Section can serve you better.
On Tuesday afternoon at 2:30 PM, the accelerator session will resume and carry through into the early evening, with our last talk scheduled for 5 PM. Afternoon talks by the foremost authorities in accelerator health physics will include Scott Walker from Los Alamos National Lab; Johannes Bauer from SLAC; George Stephens and Scott Schwahn from Oak Ridge National Lab; Mike Sandvig from Idaho National Lab; Syed Naeem, N. Robinson Neba, and Jason Harris from Idaho State; and Jeffrey Dooling from Argonne National Lab.
Finally, on Tuesday night at 7 PM, we will gather in the ballroom at the Minneapolis Hilton for the HPS Awards Banquet, where the entire society will recognize the winners of the H. Wade Patterson Memorial Award for best student papers on accelerator radiation protection. This award is meant to foster excellence in the next generation of accelerator health physicists, and your support for these students at the banquet is crucial.
As you can see, we will have a full agenda at the meeting in
Past Presidents Message
Accelerator Section election ballot for the new officers was mailed on May fourth. So far (12 hours later) the response have been very good. This year we are electing three new directors, president-elect and a newsletter editor. We have been using the latest member addresses which were provided by the HPS. However, there are still a few E-mail addresses that are not current. I am chasing those down. My final attempt will be via snail mail. Please make sure HPS has your most recent address and E-mail. Sending an E-mail to our newsletter editor would also work.
The results of the election will be announced at the section business meeting that will immediately follow the Accelerator Section's Tuesday morning special session. We have finished writing out the responsibilities of the officers of the Accelerator Section. For the presidents a timeline associated with their responsibilities is also specified. The job descriptions will be posted on our website soon.
Health Physics Society officer Nomination went very well, we received many nominations. We ended up with four nominations for the three director positions and one nomination for the president-elect. On April first we submitted the names of the nominees and the supporting documentation to the chairman of the HPS election committee. Unfortunately, our nominee for the president-elect withdrew his nominations because of additional job related responsibilities. However, our nominations for the HPS directors are very strong, please make sure to vote. We are a relatively small sector of the HPS and it is very important for us to have representation at the Society level.
The Radiation Generating Devices Midyear in January/February of 2008 must have sparked the interest of Accelerator Section Members in that we have the largest special session at the Annual Health Physics Society meeting we have had in years. We need to have a Midyear meeting about every seven years just to peak the interest of the accelerator health physics community. I would personally like to thank everyone for taking the time to make the upcoming meeting a success. Most facilities still seem to be doing fairly well in spite of the current economic down turn. Accelerator Health Physics is still a growing field with new research across a number of areas. I would also like to call attention to the timely article published in the June issue of the Health Physics Journal by Don Cossairt and Kamran Vaziri entitled: Neutron Dose per Fluence and Weighting Factors at High Energy Accelerators.
I would like to take time to think everyone for your contribution to this Newsletter. There are some very interesting items in this newsletter.
Accelerator Safety Workshop
The 2009 DOE Accelerator Safety Workshop will be held at Brookhaven National Laboratory (BNL) August 18-20, 2009. The intent is to share experience and gain consensus on how safety systems are efficiently applied to accelerator facilities operated by DOE contractors. The workshop atmosphere is informal and open discussion is encouraged. Equal participation from DOE and contractor organizations is encouraged.
The first two days include Topical Presentations with one Panel Session in the morning through lunch and early afternoon. These sessions are attended by all workshop members. Breakout Sessions in the afternoon are open to all members, but traditionally, members with specific interest in a specific topic will attend and contribute to that session. The final half-day includes an out brief report from each Breakout Session Facilitator and a discussion of the path forward. A tour of the BNL accelerators will be offered late morning of the final day.
For specific information on topics to be discussed and for registration, please visit: http://www.bnl.gov/ASWorkshop
News from Fermi Lab and SLAC
Continual Evolution of High Energy Accelerators
J. Donald Cossairt and Sayed
In the previous issue of this newsletter, L. Scott Walker
reported on the planned modernizations of the LANSCE facility at the Los Alamos
National Laboratory. In that article Scott began with a lament on how this Los
Alamos facility, once the world’s most powerful accelerator as measured by
average beam power, the product of beam current and energy, has languished into
a state of poor performance in its 4th decade of operation. Scott
stated that in some respects many of its systems are becoming obsolete and that
in that vein the
In this brief note we are proud to report that both SLAC and Fermi have been improving both adiabatically with day-to-day improvements and with regular and well-planned phase transitions. These have been are in the form of technological innovations that have resulted in both continuous and abrupt improvements in performance over the decades during which these machines have led the world in many forms of physics research. Other articles in past issues of this newsletter have enthusiastically described improvements at both facilities.
The accelerators and many aspects of auxiliary systems support for accelerators at SLAC are either completely new, or have been upgraded over the years. SLAC started commissioning of its latest facility, the Linac Coherent Light Source (LCLS) in December 2008. Many of the LCLS sub-systems, including, shielding structure, computer control, injection technology, initial acceleration, and the access control system are all newly designed, and installed. All of the beamlines and experimental facilities for the LCLS are new. The Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC completed the SPEAR 3 upgrade project in 2008. The project totally replaced the SPEAR vacuum chamber, magnets, support rafts, RF, power supplies, cable plant and shielding tunnel floor. Many of the SSRL beam lines are either newly built, or are being upgraded to be compatible for 500 mA operations in the top-off configuration for FY10. Through a number of other processes such as Accelerator Improvement Project at SLAC, many of the other accelerator support systems including infrastructure are evaluated and are routinely upgraded. The scientific and technological vision of the founder of SLAC, Dr. Wolfgang K. H. Panofsky continues undimmed into the future.
Likewise at FERMILAB, many upgrades have been conducted over
the years. While roughly the first decade of FERMILAB operations utilized the
conventional iron Main Ring synchrotron, since 1983 the highest energy proton
accelerator on the planet has been the superconducting Tevatron,
the site of discoveries of the top quark and the tau neutrino. Moreover, the Tevatron is the essential prototype of major frontier
colliding beam machines worldwide, notably the Relativistic Heavy Ion Collider
(RHIC) at Brookhaven National Laboratory and the Large Hadron
Collider (LHC) at CERN. The Tevatron collider program
was improved immeasurably with the addition of the Main Injector in 1999. The
collider program now achieves both instantaneous and integrated luminosities of
protons and antiprotons several orders of magnitude larger than envisioned when
the colliding beam program was initiated. Furthermore, FERMILAB is now the site
of the highly successful high intensity neutrino experiments MiniBooNE and NuMI. These
experiments operate reliably at very high levels of beam power. The success of
these experiments is reflective of the body of work of ongoing improvements in
the accelerator technology deployed and operated with great vigor. Presently,
FERMILAB is heavily engaged in the construction of the NOvA
neutrino oscillation experiment with groundbreaking at the site of the far
News from CAMD
CAMD recently installed a 2nd RF cavity in preparation to upgrade the facility with new insertion devices. This process went smoothly and did not provoke any health physics concerns. Soon after that, funding was received to upgrade the 7 Tesla wiggler, with a cryostat to recompress helium used by the magnet. Once the Wiggler was removed, shielding was placed upstream of the long straight section housing the 7T Wiggler. Following bake-out, there was an abrupt shift in both the patterns and intensity of radiation developed under these new operating conditions. Ramp files that had been in use during pre-wiggler days, did nothing to alleviate the problem. Careful screening of the area, using exposed film and a pin hole through a 1.58mm sheet of lead was able to pinpoint the problem. The beam pipe was found to be 6.35mm below the projected trajectory of the beam in a slightly concave fashion. Beam position monitors forward and aft of the beam loss position were unable to detect any change in beam. The beam pipe was raised, additional shielding placed in the area. Shortly thereafter, a short was found in one of the main dipole magnets. This defect is intermittent, making it more difficult to circumvent. This also requires a new orbit every day, depending on the operation of the dipole. Shielding was implemented to take care of both the dipole short and the original concave beam pipe effect. For the moment, radiation doses inside the ring have fallen from a high of 72 mSv/hr to 0.38 mSv/hr. A shutdown is planned for September to re-install the wiggler with its cryostat and to replace the bad coil in the dipole.
Until June 25th at the
close of the Louisiana Legislative session, CAMD will not know its future.
Stay tuned for more from the Bayou -
News from NSCL (National Superconducting Cyclotron
Reginald M. Ronningen
Interested readers are welcome to visit NSCL’s website www.nscl.msu.edu for news, descriptions of its programs, facilities, technologies and employment opportunities. Some of the important events and developments during this quarter were:
NSCL will soon take possession of a newly constructed experimental hall that will contain experimental stations and equipment for the ReA3 facility. Safety planning and analysis is on-going with special attention given to x-ray generation and shielding, high-voltage (up to - 60 kV) safety and to general construction safety issues related to building ReA3 on an 11 ft-high platform.
Following a month-long maintenance shutdown in January, a campaign of five experiments was performed to measure excited and ground state lifetimes, using Doppler-shifted gamma-ray energies and the Köln/NSCL Plunger Device, by groups from the University of Köln (Germany), LBNL, LLNL, University of Tennessee, NSCL, Laboratori Nazionale di Legnaro (Italy), and Saha Institute of Nuclear Physics (India); A precision measurement was made of the masses of 24Si and 23Al using the LEBIT facility; Two SeGA-S800 experiments, by groups from Florida State University and NSCL, were aimed at studying the nuclear structure of exotic nuclei with neutron numbers 28 and 50, respectively. A discretionary experiment, by a group from the University of Notre Dame with NSCL participation, was to produce a well-characterized 60Fe sample from fragmentation of a beam of 64Ni, which would then permit a re-measurement of the half-life of 60Fe with reduced uncertainty.
Noteworthy papers based on NSCL research published during the period included an article in the March 27 issue of Physical Review Letters on how heavy-ion reactions studied at NSCL provide information to constrain the symmetry energy term in the equation of state for nuclear matter at below-normal nuclear densities. This work marks the first successful theoretical explanation of the common symmetry-energy-related observables – including isospin diffusion and differences in neutron and proton emitted spectra – in heavy-ion collisions.
Commissioning of NSCL’s newest electron-cyclotron-resonance (ECR) source SuSI (Superconducting Source for Ions) continues, with tests performed using the inductively heated oven and the sputtering technique. Extraction optics was studied. Significant effort was spent on planning the move of SuSI into operations later this year. Safety assessments were part of this preparation. The plan involves not only the relocation of SuSI but also the removal of SCECR (the old superconducting ECR ion source currently in operation) from its current location.
Spallation Neutron Source
Don Gregory, Radiation Safety Officer
The big news recently is that the ORNL Authorized Limits proposal under Order 5400.5 for clearance of neutron scattering samples was approved by the local DOE office, and Headquaters made only minor editorial comments. Clearance is based on a calculation of the quantified activation products contained in samples that have been placed in neutron beams at SNS and HFIR as part of the research program at those facilities. The computer program performing the analysis takes into account the elemental make-up of the sample, exposure time, neutron spectrum and flux for the particular instrument being used, and decay from the time the sample is exposed to the time it is being considered for clearance. A measurement with a NaI detector by an RCT confirms that the calculated activation level is accurate or conservative. The initial proposal contained clearance limits for about 35 isotopes, but also included a process for adding isotopes to the approved list without additional DOE approvals - based on an approved conservative analysis process similar to that used on the initial isotopes. When we started examining actual samples we found that most samples contain Nitrogen and Silicon, but also Praseodymium or other exotic materials. The ORNL team went to a lot of trouble to properly characterize essentially every isotope so the resulting updated clearance list would not have to be updated again. The final step in preparing to clear qualifying samples from DOE radiological concern involves the "public notification" aspect of the Authorized Limits requirements. When you are sending material to a landfill, you have to notify the landfill owner and the State. ORNL and DOE agreed that clearance of samples to the research institutions owning the samples should include prior notification and formal acknowledgement by the researcher's home institution. That process is moving along and we hope to start clearing samples within the next month. The ORNL team (led by George Stephens) who developed the proposal and pushed it through the Authorized Limits process over the last year is very happy to see this project successfully completed.