Accelerator Radiation Safety Newsletter
(all articles are to be considered personal/professional in nature and do not reflect the opinions of the institutions described unless otherwise stated)
An Official Publication of the
Health Physics Society's Accelerator Section
First Quarter 2014 /
FROM THE OFFICERS
The Editor’s Message
Again, President Elect Steve Frey provides a message with his contagious enthusiasm for the amazing community in which we have the opportunity to participate. From the very beginning of my career, I have maintained the belief that accelerator health physics is the most interesting specialty within health physics, and were I to doubt it, Steve would certainly have swayed me back to the original belief!
Also in this issue, Joe McDonald is asking for expressions of interest in another dosimetry comparison exercise for high-energy reference fields. It’s been a very long time since that has last occurred, and there are a number of new dosimeters and algorithms in place… please contact Joe if you are interested and especially if you would like to participate.
Several more letters from correspondents came in, but I’ll just let you read on… enjoy!
The President Elect’s Message
Hi everyone, the recently-ended winter was long! Here in NorthCentral Pennsylvania, we have had the snowiest and coldest winter in decades. And yet, a pair of bald eagles moved into town, despite the freezing conditions, and are inspiring the public with their spectacular soaring.
Our Section continues to have great potential to energize the public as well. Case in point: we are members of the public who got here by being drawn by the cutting-edge science of high-energy physics. We enjoy our supporting role of providing radiation-safety controls for particle and photon physicists, and revel along with them when each new discovery is made. More on this in a moment.
Good news! Dr. Lorraine-Marceau Day has accepted our offer to nominate her for a Dade W. Moeller Lectureship Award. We're going to put a nomination package for her in the next few weeks. Please feel free to write an endorsement letter for her if you'd like, and send it to me at StevenFrey@aol.com. We'll be sure to include all of your letters in her package.
Around the accelerator community, there are new and interesting things going on…
FROM THE CORRESPONDENTS
Time for an Accelerator Dosimetry Comparison Exercise?
Joseph C. McDonald, PNNL
Several dosimetry comparison exercises (I’ve chosen not to use the word intercomparison, mainly because there is no such word in my Webster’s) have been carried out over the years, but I’m not aware of another one that has been performed recently. Perhaps the last one that was reported was in 2000(1). So, it might be useful to set up another one.
The National Institute of Standards and Technology does not maintain reference radiations appropriate for calibrations of dosimeters and instruments in use at high-energy accelerator facilities. That being the case, it is not possible to perform proficiency tests of accelerator dosimeters. What can be done is to establish a field that is reasonably similar to that encountered at most high-energy accelerators, and then to expose groups of dosimeters from participating laboratories to the same dose equivalent, even if the value of that dose equivalent may not be traceable to national or international standards. The results of such an exercise provide information on the consistency of measured values obtained by the participating laboratories. This is useful information for quality assurance purposes. I also believe that the exercise itself encourages communication among the participating laboratories. And that is also very useful.
The last comparison exercise was performed almost 15 years ago, and the irradiations took place at the CERN-EU high-energy Reference Field (CERF) in Geneva, Switzerland. I believe the facility is still in operation, and it still may be possible to arrange for the irradiations to be performed without charge. We were lucky to get those irradiations done for free at that time, and I think it would be worthwhile to investigate as to whether we can still arrange for such a deal. Some of our colleagues are still working at CERN.
For those who may be interested in taking part in a comparison exercise, I would suggest that you contact me and I will do my best to make it happen. I have been retired from PNNL for about 8 years now, but I am serving as an Emeritus Scientist (volunteer).
1. Stewart, R.D., McDonald, J.C., T. Otto and Loesch, R. M. Fourth Intercomparison of Personal Dosemeters Used in U.S. Department of Energy Accelerator Facilities, Radiat. Prot. Dosim. 87(2) 77-86, 2000.
The 2014 Mid-year of the Health Physics Society was held in Baton Rouge, Louisiana. As part of that meeting, the Center for Advanced Microstructures and Devices (CAMD) at Louisiana State University played host to one of two technical tours. Participants engaged researchers regarding their individual investigations, in an effort to showcase the diversity of explorations that are possible at a synchrotron. There was also time for a discussion on the accelerator aspects of the facility. We unveiled our new 7.5 T Wiggler, one of the most powerful devices of its type in the world. Commissioning for this insertion device is on-going. Like the rest of the country, Baton Rouge has been suffering from one of the coldest winters on record. A cold and rainy afternoon on the day of the tour limited the number of participants willing to brave the weather.
Commissioning of the new wiggler continues to be an on-going process, limited in part by machine characteristics. We have spent the last few months assessing the beam quality in the ring and identifying susceptible points of loss of potential consequence to radiation safety. Another part of this evaluation was focused on determining the competency of the existing shield wall. We are very pleased to report that the shield wall remains competent and that there is no need for additional shielding. We are also bringing in three new insertion device beamlines, each with a unique monochromator. Monochromators are notorious scatter devices which require additional local shielding. To complicate the shielding design, at least one of the monochromators (The Laue) will require being moved out of the beam for certain experiments. Stay tuned as we devolve the intricacies of our new insertion device and affiliated beamlines.
CAMD is pleased to announce that…
In accelerator environments there are for radiation protection two major challenges in accurate dose measurement: high energies and pulsed fields. Especially dead time effects cannot be easily overcome without the design of new technology . Therefore BERTHOLD Technologies together with DESY and STRUCK Innovative Systems in Hamburg developed the new area dose meter BERTHOLD LB 6419 for pulsed and continuous neutron and gamma radiation.
Two Reviews of the 2014 HPS Professional Developmental School, Radiation Safety in Medicine
[Editor’s Note: Mostly because I thought that it was very interesting to see the PDS from two different points of view, I am including BOTH of them for your interest.]
To see Lorraine Day’s report, please click here.
To see Mike Grissom’s report, please click here.
If you wish to contact the editor of this newsletter click here