SATIF-15 Workshop participants. Photo: courtesy of the Facility for Rare Isotope Beams (FRIB)

The 15th Workshop on Shielding aspects of Accelerators, Targets, and Irradiation Facilities  (SATIF-15) took place at the Facility for Rare Isotope Beams (FRIB) at Michigan State University on 20-23 September 2022. The workshop was chaired by Dali Georgobiani (Fermi National Accelerator Laboratory, USA) as Chair of the Scientific Programme Committee and Thomas Ginter (FRIB, USA) as Chair of the Local Organizing Committee. The workshop was sponsored by FRIB and co-sponsored by the NEA.

Support for the SATIF workshops is now part of the mandated activity of the Expert Group on Radiation Transport and Shielding (EGPRS) of the Working Party on Scientific Issues of Reactor Systems (WPRS)  of the NEA Nuclear Science Committee (NSC). The EGPRS also co-ordinates maintenance and development of the Shielding Integral Benchmark Archive and Database (SINBAD)  of reactor shielding, fusion neutronics and accelerator shielding benchmark experiments.

There was an unforeseen 2-year delay of the workshop due to the COVID-19 pandemic. Furthermore, to accommodate the participants who were unable to travel, and to protect the workshop from cancellation due to a feasible pandemic surge, the workshop was carried out in a hybrid format. There were 130 registered participants. 43 of them were registered for in-person participation; the actual number of in-person participants was 35. There were 40 registered talks, 28 of them in-person, and 14 posters. 2 oral presenters and 2 poster presenters could not make it to the workshop for personal reasons.

The workshop consisted of eight technical sessions and one poster session, and a summary session where the status of the SATIF community and its efforts was summarised, and future actions were proposed. The workshop participants had also the opportunity to tour the Facility for Rare Isotope Beams. 

Overall, there was a very impressive array of presentations, showcasing great achievements with respect to various new and emerging code modules, reviews of radiation environments at diverse facilities, as well as continuing research (such as standard concrete studies or intercomparison of particle production). Experts and developers of four major Monte-Carlo radiation transport codes – FLUKA, MARS, MCNP, and PHITS – presented the code advances, new features, and modules. Several talks featured state-of-the-art methods, such as Machine Learning implementations.

• Session 1: Facility Reports / Shielding & Dosimetry   (5 talks: 4 in-person, 1 remote):
  The session was chaired by Anna Ferrari (HZDR). The session featured the host facility radiation analysis presentation by Tom Ginter (FRIB), as well as overview of shielding analyses at the ESS, ORNL, and LANL facilities.
• Session 2: Code Status, Advances, & Model Converters  (5 talks: 4 remote, 1 in-person):
  The session was chaired by Hideo Hirayama (KEK). The highlights of the session were the presentations of major Monte-Carlo codes including the Fermilab-based MARS code.
• Session 3: Code Status, Advances, and Model Converters [continuation]   (5 talks: 3 in-person, 2 remote):
  The session was chaired by Francesco Cerutti (CERN). The session started with the presentation on recent updates and benchmarking of another major Monte-Carlo radiation code, PHITS. Several talks were devoted to new updates to the existing numerical techniques, and their applications at various facilities.  
• Session 4: Code Benchmarking & Intercomparison  (6 talks: 6 in-person):
  The session was remotely chaired by Nikolai Mokhov (FNAL). Juan Zamora (FRIB) discussed ML scaling models within the FRIB radiation analysis framework. Code intercomparison and benchmarking via a simple model analysis or accelerator shielding applications were also showcased by the presenters. Hideo Hirayama (KEK) presented the latest iteration in the series on the intercomparison of particle production, the effort that he leads with participation from the major Monte-Carlo code experts. The SINBAD task force presentation was delivered by Oliver Buss (NEA). 
• Session 5: Code Benchmarking & Intercomparison (continuation) / Induced Radioactivity & Decommissioning  (6 talks: 6 in-person):
  The session was remotely chaired by Mikhail Kostin (JLAB). Talks on code benchmarking continued with contributions from PAL and CERN. CERN and STFC colleagues also contributed to the discussion of decommissioning issues at accelerator facilities, while decommissioning of nuclear power plants was studied by a colleague from HZDR. 
• Session 6: Shielding & Dosimetry  (6 talks: 3 in-person, 3 remote):
  The session was chaired by Hee-Seock Lee (PAL). More talks from CERN described radiation analysis of the existing facilities and their upgrades. Kenichi Kimura (Fujita Corp) presented a talk on the concrete composition for radiation shielding, while Hiroshi Iwase (KEK) discussed the importance of water and iron content in concrete for neutron shielding applications. The BNL ARI-SXN beamline radiation shielding analysis was presented by Ricardo Augusto. Federico Chiarelli (INFN) delivered a talk on skyshine.
• Session 7: Source Terms / Medical Accelerators  (3 talks: 1 in-person, 2 remote):
  The session was chaired by Oliver Buss (NEA). Hee-Seock Lee (PAL/POSTECH) discussed photon-neutron emission for low-energy photons; the KEK team (Kenta Sugihara) discussed the application of a time-of-flight method to measure neutron production yields. A medical application talk (Gonzalo Fernandez, UP Madrid), devoted to new delivery methods in proton therapy at Compact Proton Therapy Centers, was not delivered because of technical problems.
  Session 7 also included two talks with the proposals for the next SATIF workshop: a proposal from GANIL and LPC Caen presented by Manssour Fadil, and another proposal from Frascati National Laboratories (INFN-LNF) presented by Raffaella Donghia.
• Poster Session  (12 posters):
  Session 7 was followed by the Poster Session that was organized due to a high number of submitted contributions. The virtual poster session was set up in Gather Town to enable simultaneous participation by in-person and remote participants. Out of 14 registered posters, 12 were presented and discussed in lively virtual conversations.
• Session 8: Radiation Damage / High Intensity Laser Facilities / Techniques & Applications  (5 talks: 1 remote, 4 in-person):
  The session was chaired by Reg Ronningen (FRIB, retired). This session featured radiation damage analysis (Yosuke Iwamoto, JAEA), laser facility advancements from HZDR and ELI Beamlines, and discussions of new methods for plugging penetrations (Ralf Buckermann, Framatome). The session was concluded by Yasuhito Sakaki (KEK) with a discussion of atmospheric-like neutrons and muons at the ILC beam dumps.
• Concluding Session: Summary, Future Actions, SATIF-16:
  The summary session was chaired by Dali Georgobiani (FNAL); she also summarized workshop highlights, spoke about future actions, and delivered closing comments. Oliver Buss (NEA) presented information pertaining to workshop proceedings preparation, logistics, and timeline. The summary session is where future activities of the SATIF community, including various proposed collaborations, can be discussed. The participants are always welcome to propose further needs and tasks aligned with the SATIF framiework.

The workshop resulted in the following major conclusions:

• Discussion surrounding the advancements and utilization of major radiation transport codes stands as a cornerstone within SATIF. SATIF-15 has shown significant progress in code intercomparison and benchmarking, pivotal for ensuring accuracy and reliability..
• SATIF-15 featured radiation environment assessments for emerging, new, and upgraded facilities employing novel techniques.
• The participation of heavy ion facilities like the FRIB as host of SATIF-15 has introduced intriguing new issues into the discourse, underscoring the evolving nature of the field.
• The observation of few proposed talks on medical accelerators or material damage perhaps suggests the need to re-attract experts from this field into the SATIF community. The few talks covering the emerging field of laser facilities was less unexpected.
• A disconnect between the code developers and the experts performing code benchmarking and intercomparison was observed and emphasizes the importance of cohesive collaboration. Efforts to reconcile differences in code results, particularly in comparison to experimental data, are crucial and  differences in the underlying physics models should be investigated. The commendable work by the PHITS team exemplifies this, continuously refining its physics models based on rigorous code-to-experiment evaluations.

Throughout the workshop, the objectives and activities of the SATIF community were emphasised. Traditionally, the meeting highlighted the importance of simulation code intercomparison, benchmarking simulation results with experimental data, gathering such data as a result of dedicated and organized experimental studies, as well as current results and achievements and future plans on code development. As with earlier SATIF community gatherings, code developers received requests to add new features to the codes in order to improve code application to shielding design and other implementations.

Following the tradition of rotating the SATIF workshop venue between America, Europe and Asia, the next SATIF workshop (SATIF-16) will take place in Europe. INFN-LNF in Frascati, Italy, was selected as the site for SATIF-16 based on a vote of the SOC (6 for INFN-LNF, 4 for GANIL, 1 neutral, 5 not respoding).  It is scheduled for May 28-31, 2024.