Measured Radiation and Background Levels During Transmission of Megawatt Electron Beams Through Millimeter Apertures

Journal Article · Fri Nov 01 00:00:00 EDT 2013 · Nuclear Instruments & Methods in Physics Research, Section A

DOI:https://doi.org/10.1016/j.nima.2013.06.042· OSTI ID:1089403

Alarcon, Ricardo ^[1]; Balascuta, S. ^[1]; Benson, Stephen V. ^[2]; Bertozzi, William ^[3]; Boyce, James R. ^[2]; Cowan, Ray ^[3]; Douglas, David R. ^[2]; Evtushenko, Pavel ^[2]; Fisher, P. ^[3]; Ihloff, Ernest E. ^[4]; Kalantarians, Narbe ^[4]; Kelleher, Aidan Michael ^[3]; Krossler, W. J. ^[5]; Legg, Robert A. ^[2]; Long, Elena ^[6]; Milner, Richard ^[3]; Neil, George R. ^[2]; Ou, Longwu ^[3]; Schmookler, Barack Abraham ^[3]; Tennant, Christopher D. ^[2] ; Tschalar, C. ^[3]; Williams, Gwyn P. ^[2]; Zhang, Shukui ^[2]

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1. Arizona State University, Glendale, AZ (United States)
2. Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
3. Massachusetts Institute of Technology, Cambridge, MA (United States)
4. Hampton University, Hampton, VA (United States)
5. William and Mary College, Williamsburg, VA (United States)
6. University of New Hampshire, Durham, NH (United States)

We report measurements of photon and neutron radiation levels observed while transmitting a 0.43 MW electron beam through millimeter-sized apertures and during beam-off, but accelerating gradient RF-on, operation. These measurements were conducted at the Free-Electron Laser (FEL) facility of the Jefferson National Accelerator Laboratory (JLab) using a 100 MeV electron beam from an energy-recovery linear accelerator. The beam was directed successively through 6 mm, 4 mm, and 2 mm diameter apertures of length 127 mm in aluminum at a maximum current of 4.3 mA (430 kW beam power). This study was conducted to characterize radiation levels for experiments that need to operate in this environment, such as the proposed DarkLight Experiment. We find that sustained transmission of a 430 kW continuous-wave (CW) beam through a 2 mm aperture is feasible with manageable beam-related backgrounds. We also find that during beam-off, RF-on operation, multipactoring inside the niobium cavities of the accelerator cryomodules is the primary source of ambient radiation when the machine is tuned for 130 MeV operation.

• Research Organization: Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1089403
• Report Number(s): JLAB-FEL-13-1741; DOE/OR/23177-2576; arXiv:1305.7215; TRN: US1300310
• Journal Information: Nuclear Instruments & Methods in Physics Research, Section A, Vol. 729
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
background radiation
beam transmission
energy recovery linac
megawatt electron beam
millimeter aperture
multipactoring