INTERNATIONAL ACCELERATOR RADIOLOGICAL PROTECTION E-MAIL (IARPE) NEWSLETTER "The Official Publication of the Accelerator Section of the Health Physics Society" (with Contributions from International Correspondents) ====================================================================== November/December 1995 Circulation: 221 Vol. 4, #6 ====================================================================== OFFICERS ====================================================================== President: Bob May, CEBAF President-Elect: Lutz Moritz, TRIUMF Past President: Nisy Ipe, SLAC Secretary: Steve Musolino, BNL Treasurer: Carter Ficklen, CEBAF Newsletter Editor: Vashek Vylet, SLAC Directors: Jeff Leavey (1998) Tracy Tipping (1998) Lorraine Day (1997) Don Cossairt (1997),FNAL De Vaughn Nelson (1996) Paula Trinoskey (1996),LLNL ====================================================================== CONTENTS From the Editor From the President Obituary Conference Announcement Feature article: Boron Neutron Capture Therapy News from correspondents: ICRU/ICRP, CEBAF, CERN, KEK, BNL, FERMILAB, SLAC How to subscribe or update subscription Closing thoughts >From the Editor Vashek Vylet ====================================================================== H. W. Longfellow once wrote: "Into each life some rain must fall". So must we bring sad news in this issue: Joe McCaslin passed away. Those of us, who knew Joe only from his scientific papers, will get a more personal picture of Joe's character from the obituary by Wade Patterson, Joe's long time colleague at LBL. Second sad news is the decision of the HPS Board of Directors not to select Bob May, Accelerator Section President, as a delegate to the upcomming IRPA meeting in Vienna. It appears that, unfortunately, our petition did not meet the deadline for nominations of IRPA delegates. Before we got all the facts straight, there was a lot of e-mail discussion within the Accelerator Section Board questioning the selection procedure. Although it is clear now that a proper procedure was followed, as described in the Rule 11.1, all this discussion made me realize one worrisome fact: currently, none of the 17 HPS Officers/Board Members/Editors is member of our Section! Having a voice on the Board would help in many ways. It is therefore desirable that Section members increase their participation in various activities of the HPS, which should ultimately lead to a better representation at the highest echelons. I would like to thank all the correspondents for their interesting articles and for helping to keep IARPE alive. Besides the excellent feature article on BNCT by Rick Donahue, don't miss the ICRP/ICRU news from Ralph Thomas. It brings an important update on conversion coefficients for external radiations. Manfred Hoefert's suggestion about publishing IARPE on WWW (see News from CERN) is well taken. I must confess that I thought about this long time ago. However, it would make sense only if the vast majority of our readers have access to WWW, with adequate computer hardware and software. It would also require a little more effort from the correspondents: besides getting pictures in gif or jpeg format on their machines, they need to encode them, to make it possible sending them by e-mail. Please let me know your opinion on this subject. >From the President Bob May ====================================================================== With apologies for some repeat information, I've included as my report for this newsletter the Accelerator Section Report sent to the HPS Board for the Midyear meeting. It provides up-to-date information on several two key issues... the CASOG activities and recommendations to the ANSI N43 Committee on a Chair for the N43.2 Writing Comittee. It also serves as a reminder on other important activities. Report on the activities of the The Accelerator Section of the Health Physics Society 1) The Accelerator Section publishes a bimonthly international newsletter via electronic mail called the International Accelerator Radiation Protection E-Mail Newsletter. The newsletter serves over one hundred HPS Members, IRPA Affiliates, and other interested parties. The newsletter contains a range of topics on radiation protection activities at high energy particle physics accelerators and state and federal regulatory initiatives. 2) The Section has a committee (CASOG) dedicated to review of the guidance provided by DOE with Order 5480.25, Radiation Protection at Accelerators. Recently the CASOG has produced a draft technical paper on the selection of reliablity levels for interlocks and other safety devices. The draft technical paper has been reviewed by the Accelerator Section's Scientific Panel - Senior Scientists at Fermi National Accelerator Laboratory (J. Donald Cossairt) and Stanford Linear Accelerator Center (Kenneth R. Kase). The draft is currently under review by Bob Youngblood at Brookhaven National Laboratory who is a member of a Nuclear Regulatory Commission review panel. We hope to submit this for review by the ANSI N43 group in early 1996. 3) The Section is collaborating with the North California Chapter (NCC) to plan the HPS 1997 mid-year meeting in San Jose. The Accelerator Section proposed the subject "Health Physics of Radiation Generating Machines" and expressed interest in organizing the technical program. Usually, the local chapter takes care of local arrangements and also has the choice to decide whether or not to organize the technical program. Although the NCC seemed to have given up the latter, due to minor miscommunication, this issue and its financial aspects were not fully resolved until recently. Vashek Vylet, a program committee co-chair, attended a recent meeting of the NCC Board of Directors on behalf of our Section . After a short friendly discussion, he reached the following agreement with the NCC: 1) The NCC leaves the organization of the technical program to the Accelerator Section 2) The Accelerator section will donate half of its proceeds (i.e. $1000) to a charitable program under the custody of NCCHPS, such as the Moyer Fund. The program committee co-chairs, Vashek Vylet and Lutz Moritz, are fostering strong international participation and are working on a "Call for Papers". 4) As requested by Tony LaMastra, the Accelerator Section has suggested someone to chair the ANSI N43.2 Writing Committee. The Section has forwarded the name of James Liu, a Stanford Linear Accelerator Center Scientist, who is known to have the background, drive, and organization talent necessary for such an undertaking. The selection is pending. I offer to all my sincere wishes for a happy holiday season and a peaceful new year. OBITUARY Wade Patterson ====================================================================== Joseph B. McCaslin The world lost a person of worth and character when Joe McCaslin passed away on November 10,1995. Joe was a valued and important member of the Health Physics group at Lawrence Berkeley Laboratory for many years prior to his recent retirement. He is perhaps best known as the developer of the plastic scintillator as a high-energy neutron detector via the 12C-n,2n-11C reaction. He pioneered the use of MOSFET devices to produce ultra-stable and ultra-sensitive ion chambers. Additionally, his accomplishments on accelerator shielding problems were noteworthy. Joe's work was relied on without question. He was careful and thorough and had a complete command of the physics and electronics that were necessary for his work as a radiation and health physicist. His attitude toward those with whom he worked was invariably helpful and courteous. He was always a pleasure to be with, as a friend and as a colleague. No matter what Joe did one was always sure that it would be correct, on schedule, and accomplished with maximum efficiency. He leaves a devoted wife Marge, a son, Jason., and a daughter, Joann, along with many bereaved friends. H.Wade Patterson CONFERENCE ANNOUNCEMENT James Liu ===================================================================== There will be an International Conference on Radiation Dosimetry and Safety in Taipei (Capital of Taiwan, Republic of China) between March 31 and April 1, 1997. The conference covers most major areas of health physics and radiation physics. There will also be short courses on March 27-28. If you are interested, please contact Prof. C. J. Tung of National Tsing Hua University (cjtung@ins.nthu.edu.tw) or Dr. Steve Sims of ORNL (simscs@ornl.gov) for more information or material. Thank you and looking forward to your participation. James C. Liu FEATURE ARTICLE Rick Donahue ===================================================================== BORON NEUTRON CAPTURE THERAPY (BNCT) It has been over 50 years since Boron Neutron Capture Therapy (BNCT) was first proposed by Locher(1) for the treatment of malignant tumors. The principle relies on the selective loading of tumor cells with compounds containing B-10 and subsequent irradiation with thermal neutrons. In the reaction B-10(n,alpha)Li-7 the reaction products have ranges on the order of the diameter of a cancer cell (<10um) In principle the damage can be highly localized allowing surrounding healthy tissue to survive. This modality is particularly attractive for treating glioblastoma multiforme, which usually consist of a main brain tumor with accompanying often microscopic fingerlets, as well as for treating deep-seated (inoperable) cerebral metatastases. Early clinical trials were plagued by a lack of therapeutic efficacy for several reasons. Early boronated compounds did not achieve the selective uptake in tumors. In addition, the neutron spectrum from reactors used as neutron sources is highly thermalized and would therefore provide only superficial tumor treatment in tissue. More encouraging results by Hatanaka(2) have been demonstrated using improved boronated drugs and craniotomies (removing sections of the skull!) to increase treatment depth since the penetration of such a beam is limited to a few centimeters in tissue. More recently BNCT has gained further momentum due to a new generation of boronated drugs. Kahl and collegues(3) at the UCSF Medical School have shown selective uptakes of boronated porphyrins (BOPP) as high as 400:1 relative to normal tissue in mice tumors. The process is underway for toxicity testing in humans. In addition it is now generally accepted that epi-thermal neutron sources (~1 eV - 10 KeV) will prove to be optimal for human clinical applications due to their increased treatment depth. For this many facilities are proposing accelerator-based sources which would alleviate the need for the construction of new reactors in metropolitan areas. For example a proposal by Blue and collegues at Ohio State University(4) calls for a 10 mA 2.5 MeV Radio-Frequency Quadrupole (RFQ) proton accelerator with a Li-metal target to utilize neutrons produced via the reaction Li-7(p,n). Neutron spectrum from the target is typically between 200 and 800 KeV in the forward direction for this incident proton energy and therefore requires quite a bit of moderation before exposing a patient. Treatment times are postulated to be on the order of one hour and may be spread over several fractions. LBL(5) has proposed the use of Electrostatic Quadrupole (ESQ) accelerators capable of 100 mA proton currents which which were developed as injectors for heavy ion induction linac drivers for inertial fusion reactor research. In September of last year INEL organized the First International Workshop on Accelerator-Based Neutron Sources for BNCT. For those interested in radiation transport work there are many unique challenges in this area. To give a few examples: neutron spectra from many candidate targets must be modelled through optimized moderator/reflector designs to shape spectra for a particular tumor depth and B-10 loading while minimizing gamma production; neutron RBE's must be folded in which vary with energy, tissue/tumor composition and boron loading and even with the number of fractions; deep-penetration techniques and unique optimization tools are required for both moderator/reflector design but also patient treatment planning; precise measurement of the neutron spectrum (~1 eV to ~100 KeV) must be made prior to treatment as opposed to conventional monoenergetic radiation treatments (x-ray, proton, etc.); the design of a compact moderator/reflector/shield assemblies to minimize the possible retrofitting of existing shielded rooms, and so on. Perhaps some day in the not-to-distant future many hospitals will be retrofitting their radiation therapy rooms to include BNCT facilities. For those interested in conferences, the Institute for Medical Radiobiology of the University of Zurich and the Paul Scherrer Institute have announced the Seventh International Symposium on Neutron Capture Therapy for Cancer to be help 4-7 September 1996 in Zurich. For information contact the Secretariat, Mrs. L.A. Margelos-Williams at margelos@imr.unizh.ch. References (1) G.I. Locher, "Biological Effects of Therapeutic Possibilities of Neutrons", Am. J. Roentgenol., 36 (1936 1. (2) H. Hatanaka, "Clinical Results of Boron Neutron Capture Therapy," in Proceedings of the International Workshop on Neutron Beam Design, Development and Performance for Neutron Capture Therapy, Harling, Bernard and Zamenhof (Eds.) MIT March 29-31 (1989). (3) S.B. Kahl, et.al., "Selective Uptake of a Boronated Porphyrin in an Animal Model of Cerebral Glioma", Proceedings of the National Academy of Sciences of the United States of America, 89 (5):1785-9 (1992). (4) C.K. Wang, T.E. Blue and R. Gahbauer, "A Neutronic Study of an Accelerator-Based Neutron Irradiation Facility for Boron Neutron Capture Therapy", Nuclear Technology, Vol. 48 (1989) 93-107. (5) J.W Kwan, et. al., "Electrostatic Quadrupole DC Accelerators for BNCT Applications" in Proceedings of the First International Workshop on Accelerator-Based Neutron Sources for Boron Neutron Capture Therapy, Jackson, Wyoming, Sept. 11-14 (1994). NEWS FROM IARPE CORRESPONDENTS ====================================================================== News from ICRP/ICRU Ralph H. Thomas ---------------------------------------------------------------------- Conversion Coefficients for External Radiations Early in September, at its meeting in Wurzburg the International Commission on Radiological Protection (ICRP) accepted the report of a Joint ICRP/ICRU Task Group on External Radiation. A week later, some 230 km to the Northwest in Lennep, the report was also endorsed by the International Commission on Radiation Units and Measurements (ICRU). The report will be of general interest to dosimetrists and in particular to those interested in the estimation of the doses arising as a result of the irradiation of the human body by ionizing radiations from sources outside the body. Two sets of quantities are of importance in radiological protection. Dose limits are expressed in terms of protection quantities and compliance with these limits can be demonstrated by a determination of the appropriate operational quantity. In Publication 60 the ICRP made significant changes in its definitions of the protection quantities and recommended that the equivalent dose, DT, and effective dose, E, be used in radiological protection (ICRP 1991). These protection quantities are not directly measurable. For exposure of humans by sources of radiation outside the body (external radiations), the convention has been adopted that operational quantities defined by the International Commission on Radiation Units and Measurements (ICRU) should be used for practical measurements. The two sets of quantities may be related to radiation field quantities such as particle fluence and in turn, by sets of conversion coefficients, to each other. The operational quantities now in use, ambient, directional and personal dose equivalent, [H*(d), H'(d) and Hp(d)], were originally defined to be compatible with protection quantities defined by ICRP in the seventies (ICRP 1977; ICRU 1985, 1988). Since that time ICRU has published clarifications to the definitions of the operational quantities; new physical data bases have become available and improvements have been made in the methods of performing radiation transport calculations. These improvements in physical data and computational techniques would alone warrant a review of the conversion coefficient data provided in ICRP Publication 51 (ICRP 1987). The significant changes made in the definitions of the protection quantities in ICRP Publication 60 and the modifications to the definitions to the operational quantities naturally raise questions as to whether the operational quantities, as currently defined, are still a good measure of the new protection quantities. In 1991 the ICRP and ICRU set up a Joint Task Group that was requested to review published conversion coefficient and related data and to provide to an agreed set of reference conversion coefficients data for application to external dosimetry for radiological protection. Members of the Joint Task Group were: Full Members: Larry W. Brackenbush PNWL, USA Jean-Louis Chartier IPSN, France Michael J. Clark NRPB, UK Gunter Dietze PTB, Germany Gunter Drexler GSF, Germany Hans G. Menzel CEC, Brussels Chair: Ralph H. Thomas University of California, USA Corresponding Members: Richard Griffith IAEA, Vienna. Bernd L. Grosswendt PTB, Germany Nina Petoussi GSF, Germany. Bernd R. L. Siebert PTB, Germany. Maria Zankl GSF, Germany. The Joint Task Group was asked to: - provide conversion coefficients for protection quantities. - provide conversion coefficients for operational quantities. - examine the relationship between protection and operational quantities. The new report, which will be published next year, revises and replaces much of the data given in ICRP Publication 51 and in ICRU Report 43 (ICRU 1988). The Report analyses the consequences of the changes in the definitions of the protection quantities recommended in ICRP Publication 60 and, finally, demonstrates that the operational quantities still function as adequate predictors of the protection quantities i.e., that in most practical circumstances they neither under-estimate nor significantly over-estimate protection quantities. Published data were reviewed for photons with energies up to 10 MeV; for neutrons with energies up to 180 MeV and for electrons with energies up to 45 MeV. The review was not extended to higher energies because data are not yet been available for the protection quantities defined in ICRP Publication 60. Reference conversion coefficients relating the protection and operational quantities and to the appropriate physical quantities (e.g., air kerma, absorbed dose or particle fluence) are in the report. ICRP Publication 60 redefined the Protection Quantity recommended in ICRP Publication 26 (Effective Dose Equivalent) essentially by changing the organs and tissues to be considered, recommending new tissue weighting factors and finally by changing the method by which absorbed doses be modified to account for radiation quality. The Operational Quantities have been changed both by the revision of the Q-L relationshipin ICRP Publication 60 and new stopping power data reported in ICRU Report 49. The Joint Task Group Report examines the consequences of these changes in some detail and concludes that, in most practical circumstances, the operational quantities defined by ICRU in 1985 still provide a satisfactory basis for measurements for radiological protection against external radiations. Remarkably, this is so despite changes the definitions of the protection quantities; changes in the specifications of the operational quantities; new physical data and improved methods of calculation. For photons and electrons, measurement of the operational quantities for area monitoring will continue to provide a reasonable over-estimate (typically 20% or more) of the protection quantities in all irradiation geometries. For neutrons the results are more complicated. In most, but not all, irradiation geometries the situation is similar to that for photons and electrons. There is a particularly important exception for the AP geometry at low neutron energies (about 1 eV) where underestimates of the protection quantity by about 25% can occur. Particular caution is also required when dealing with neutrons (and other radiations) having energies above about 20 MeV, because the operational quantities defined at a depth of 10 mm in tissue may not provide sufficient over-estimation of protection quantities. In those cases where the operational quantities prove to be unsatisfactory the data provided in the report provide a basis for the design of adequately protective measurement programmes, the correct interpretation of measurements results and their relation to the protection quantities. It is most important to stress that, if reliable results are to be obtained, knowledge of the neutron spectrum in which measurements are to be made is always highly recommended. News from CEBAF Bob May ---------------------------------------------------------------------- CEBAF Beam in Use for Physics On 5 November 1995 the CEBAF accelerator began reliably producing stable 24 microampere cw beam at the design energy of 4 GeV in a design-maximum five full acceleration passes. The current corresponds to 97 kW of beam power. Experimental nuclear physics in Hall C began 15 November 1995. The accelerator delivered 3 coulombs to the hall in the first ten days. Typical operating parameters were 1645 MeV at 5 to 20 microamperes. Availability during the first run was better than 80%. Users have been delighted with initial research operation of the accelerator. The present operational status follows intensive efforts to understand and stabilize accelerator performance. These consolidation efforts -- undertaken since the earlier reports of initial full-energy beam and then initial cw full-energy beam -- focused on setup adjustments for the accelerator's 2300 beam transport magnets, with significant concentration in the area of control software refinements. As a result, experimenters can now be supplied with beam from any number of passes up to the design maximum, a capability now being exploited. Summer Graduate Program at CEBAF Applications are being accepted for the eleventh annual Hampton University Graduate Studies (HUGS) at CEBAF, to be held June 2 to June 19, 1996. The program, supported by DOE and NSF, is designed for second- and third-year physics graduate students who have finished (or nearly finished) their coursework. Any student who is well into a research project is encouraged to apply as well. Students will receive from one to six credit hours from Hampton University, located 13 miles from CEBAF The intensive but casual and friendly program includes lectures and seminars, with each student formally committing to document a specific lecture topic for the HUGS proceedings, compiled after the summer program ends. The curriculum includes substantial interaction with HUGS lecturers -- leaders in their fields invited from American universities and abroad -- as well as with CEBAF's scientific staff. Students receive excellent insight into the physics research being conducted at CEBAF. A few fellowships are available; each covers tuition and fees, room and board, and up to the total cost of travel (from U.S. point of entry, for a foreign student). Fellowships do not cover incidental expenses. Daily transportation to and from CEBAF is provided. Acceptance is competitive. To apply, please submit an application letter with two concurrent letters of recommendation. The submission automatically places the applicant in the fellowship competition. All students will be notified by mid-March. Additional information is available from: Ms. Carlane Pittman 804 727-5928 Pittman@CEBAF.GOV Please send applications or other correspondence to: Dr. Jose' Goity Chair, Local Organizing Committee Nuclear/High Energy Physics (NuHEP) Research Center of Excellence Department of Physics Hampton University P.O. Box 6172 Hampton, VA 23668 Bob May Radiation Control Group Head Continuous Electron Beam Accelerator Facility News from CERN Manfred Hoefert ---------------------------------------------------------------------- With Alberto Fasso presently in Japan installing FLUKA and enjoying sushi, there are only three physicists remaining in RP: Graham Stevenson, Jan Tuyn and myself. But hark there is relief coming in 1996 with Marco Silari starting on 1 January taking over from Alberto the job as a section leader for the Prevessin Site where radiation doses in LEP became noticeable following the energy increase from 46 to 68 GeV and the SPS beating all intensity records supplying protons to the neutrino experiment and high intensity lead ion beams in both the West and North experimental halls. On 1 March another high caliber physicist Thomas Otto will take over the section of individual dosimetry and calibration. Here our priorities are to fulfill the requirements for an accreditation of our laboratory as becoming authorized to perform the calibration for our field instruments and monitors according to the Swiss Ordinance. The accreditation for CERN's individual dosimetry service is actually overdue and must be renewed. So we are really in need of these two young and dynamic colleagues and look eagerly forward to integrate them into our team. There is other good news: The text of CERN s new Radiation Safety Manual was approved by our Host State Authorities in matter of radiation protection and is now in the hands of the grammarians and proof readers for polishing the original French and the translated English text. Printing of the document should start in early 1996. The CERN Bulletin of this week published a leading article decorated with a nice cartoon (the IARPE Newsletter should be on the WWW for the transmission of pictures) with the title: Cosmic ray service for aircrews at CERN Aircrew receive the highest collective dose from neutrons of any professional group. The experience and expertise of CERN's Radiation Protection Group is helping to assess this exposure by simulating at the SPS the radiation field 10 000 meters up in the sky. Cosmic rays, particles originating in outer space, collide with the Earth's atmosphere producing secondary particles, some of which pass through everything they encounter, including mountains, seas, air and aircrews. The intensity and composition of the radiation field changes with latitude, altitude, and with solar activity. At sea level, the atmosphere gives the equivalent protection of about four metres of concrete, whereas at 10 000 metres a pilot's protection is only equivalent to one metre of concrete. Aircrew receive a radiation dose of 5 milli-Sievert (mSv) in a year. Accurate dose measurement is vital for all members of the crew. To be able to assess correctly the exposure of aircrew, and to make sure the instrumentation that measure radiation are calibrated correctly, a field reference facility providing a known dose of radiation is needed. As a joint project between CERN and Commission of the European Communities (CEC), such a facility was built at the Prevessin site in 1992. In the facility's 48 exposure locations, precisely measured doses of radiation come from a secondary field produced by a copper target which has been bombarded by hadron beams at energies greater than 100 GeV and which then passes through 80 cm of concrete. The instruments which measure radiation can be tested and calibrated by comparing their response with this known dose. In addition to the assessment of aircrew exposure, radiation protection groups from European accelerator and radiation protection laboratories can also compare and test their instrumentation at the CERN facility. Thanks to comparisons at CERN, both European Laboratories and air transport companies have increased confidence in their radiation measurement techniques. Whatever journalist tried to interpret into our experimental activities here follows the factual news about the future. I have sent this information to all colleagues who have profited so far from the CERN-EU Reference Radiation Facility: Dear colleagues, the EU-CERN Reference Radiation Facility will continue to be sponsored by the European Union in the coming years and will operate in 1996 on two occasions. These dates have just been fixed but cannot be fully guarantied as they may be subject to change e. g. in case of severe problems with the CERN accelerator chain. The two periods are: Thursday, 9 May at 14.00 hours to Tuesday, 14 May at 8.00 hours and Monday, 29 July at 8.00 hours to Friday, 2 August at 8.00 hours. During the second period there will be a SPS machine development on Wednesday with no beam for the users. In both runs the beam energy will be limited to 120 GeV/c positive hadrons on the production target but there should be enough intensity available to reach the usual dose rates and doses for instruments and passive detectors respectively. It would be nice if you could give me a sign of your potential interest in participating in these runs such that we could plan for the running periods well in advance. I wish you all a Merry Christmas and a good 1996, yours, Manfred Hoefert News from KEK Hideo Hirayama ---------------------------------------------------------------------- ATF injector Linac succeeded the first beam acceleration KEK is constructing Accelerator Test Facility (ATF) to study accerator technology for next generation linear collider in TeV range. ATF consists of injector linac (1.54 GeV) and damping ring. Recently ATF injector linac succeeded the first beam acceleration. Now, the beam energy is 1.27 GeV and the acceleration gradient is 26 MeV/m, which is the top record gradient among accelerators above 1 GeV. Beam current is 9.6 nA now. When RF processing is completed, the beam energy and the gradient will be increased to 1.54 GeV and 33 MeV/m respectively. The dampling ring operation will start at the end of 1996. News from BNL Steve Musolino ---------------------------------------------------------------------- On November 9, 1995, gold ions were transported for the first time from the Alternating Gradient Syncrotron through 400 meters of the AGS to RHIC Transfer Line. The Relatavistic Heavy Ion Collider is now officially linked to BNL's chain of accelerators, starting from the Tandem Van deGraaff. The successful commissioning of the Transfer Line is a major step towards the next phase of the RHIC construction which will be to send a proton beam into the addtional 250 meters of the Transfer Line and then to into one sixth of of the superconduction magnets and beam pipe that will make up the counterclockwise ring of the Collider. News from FERMILAB Dave Boehnlein ---------------------------------------------------------------------- As the old song goes, "Christmas is coming, the goose is at the lab." Actually, many geese are at the lab; thousands of Canada Geese flock here for the winter to frolic merrily in Fermilab's cooling ponds. They may get a little chilly this Christmas, though. For the first time, Fermilab will shut down over the holidays as a cost-saving measure. There will be an interruption of the ongoing collider run, beginning December 22 and lasting until January 2. The collider is now running "low energy" stores (315 GeV and 630 GeV; as Einstein would say, it's all relative). The collider experiments hope to measure cross sections for QCD jets, muons, and photon production at these energies. A collider store typically consists of 6 "bunches" each of protons and anti-protons circulating in opposite directions. In a noteworthy achievement, the accelerator staff succeeded in generating a 36 x 36 bunch proton-anti-proton store in November. Those who wont to take an afternoon walk around the anti-proton ring now find their path blocked by a vast trench which will one day contain the 8 GeV proton line to connect the Booster to the Main Injector. Work on this project continues apace. Meanwhile, beamline operators, experimenters and radiation safety personnel continue to gear up for the coming fixed target run. Plans for training, monitoring, access to enclosures, etc. must be put together and implemented, since these will be quite different for fixed target operations than for collider operations. This is not to mention the fact that the regulatory world changes for us (and all DOE labs) on January 1, when we must be in full compliance with 10 CFR 835. Naturally, we've been looking very carefully to make sure we have "all our geese in a row." I sign off wishing a very happy and fully compliant holiday season to all. Recent papers: Thomas K. Kroc, "Low Intensity Configuration at the NTF [Neutron Therapy Facility] for Microdosimetry and Spectroscopy", Fermilab TM-1940 News from SLAC Vashek Vylet ---------------------------------------------------------------------- 1. New 50 GeV A-line The "A-line" beamline directs electron beams from the SLAC two-mile linear accelerator to the End Station A (ESA), where various fixed-target experiments are conducted. To continue the efforts in the study of the spin structure of the proton and neutron (Experiments E-154 and E-155), the A-line was upgraded to 50 GeV. The Radiation physics group was heavily involved in the whole project. In the design period, we issued radiation protection plans for the new 50 GeV A-line, which included the summary of ray-trace studies, the design of the Beam Containment System and the Personnel Protection System, as well as shielding calculations. A new radiation problem was to calculate the muon radiation from 50 GeV electrons incident on thick targets, and estimate its transport through the A-line tunnel to the End Station A. The Radiation Protection plans were approved by SLAC Radiation Safety Committee in May, 1995. The A-line was successfully commissioned in September, 1995. During the commissioning period, radiation surveys were performed in different areas around ESA by the Radiation Physics group. These measurements agreed with calculations within a factor of two. Radiation leakage was measured on the first PPS stopper, slit SL-10, to make sure that it was fully closed when its microswitches were made up. The three-month running period for Experiment E-154 was finished in November, 1995. The radiation physics group was also asked to shield a CCD camera located inside the A-line tunnel, which was used to look at the synchrotron radiation from the A-line, and display the energy deviation of the passing electron beam. This camera was tested in different radiation fields. It was found that the CCD array was very sensitive to neutron radiation - a dose of a few rads was sufficient to cause permanent dammage. Stan Mao and Sayed Rokni 2. Neutron Conference in Paris The 8th International Symposium on Neutron Dosimetry was held in Paris between Novermber 13-17, 1995. Most participants were from Europe and only a few of us were from the U.S. (due the government budget problems?). The choice of invited speakers and discussion panel members were slanted towards nuclear power industry, with no representation from the accelerator community. Fortunately, the papers and posters presented by attendants reflect a significant interest in high energy neutron dosimetry and spectrometry. This interest comes not only from the accelerator community, but also from agencies involved in monitoring doses to airline crews. A few of the presented papers were of crucial importance to the area of high energy neutron spectrometry. The proceedings are to be published as a special issue of the "Radiation Protection and Dosimetry" journal. Two papers were presented from SLAC (see below), preprints are avalable upon request. Vashek Vylet and James Liu 3. New publications: V. Vylet, J. C. Liu, S. H. Rokni and L.-X. Thai: Measurements of Neutron Spectra at the Stanford Linear Accelerator Center" - to be published in Radiation Protection Dosimetry J. C. Liu, W. R. Nelson, K. R. Kase, and X. S. Mao: "Calculations of the Giant-Dipole-Resonance Photoneutrons Using the Coupled EGS4-MORSE Codes" - to be published in Radiation Protection Dosimetry S. Mao, K. R. Kase, W. R. Nelson: "Giant Dipole Resonance Neutron Yields Produced by Electrons as a Function of Target Material and Thickness" - to be published in Health Physics 70 (2):207-214. HOW TO SUBSCRIBE / UPDATE YOUR E-MAIL ADDRESS ====================================================================== To add yourself to the mailing list for the IARPE Newsletter, send an e-mail message to listserv@slac.stanford.edu The body of your message should contain the following command: subscribe iarpe-l Please don't forget to update your e-mail address if you move, change jobs or just change your computing environment. The update consists in canceling the old by 'unsubscribe' and submitting a new subscription, as illustrated below: unsubscribe iarpe-l your_old_email_address subscribe iarpe-l end If the body of your message, as in this example, contains more than a single line/command, it is good practice to finish with the 'end' command, especialy if your mailer adds a signature. If you experience problems with subscribing/updating, please send me an e-mail to vylet@slac.stanford.edu and I will do it for you. CLOSING THOUGHTS (Holiday Extended Version - Mark Twain special) ====================================================================== "There is nothing so annoying as to have two people talking when you're busy interrupting." "Suppose you were an idiot, and suppose you were a member of Congress, but I repeat myself." "I believe I have no prejudices whatsoever. All I need to know is that a man is a member of the human race. That's bad enough for me." "Get your facts first, and then you can distort them as much as you wish." "The problem with common sense is that it just ain't common." -- Mark Twain ********************************************************************** HAPPY HOLIDAY SEASON TO ALL !!! **********************************************************************