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Title: DarkLight radiation backgrounds

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-on, 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 CW beam through a 2 mm aperture is feasible with manageable beam-related backgrounds. We also find that during beam-off, RF-on operation, field emission inside the niobium cavities of the accelerator cryomodules is the primary source of ambient radiation.
Authors:
 [1] ;
  1. Department of Physics, Hampton University, Hampton VA 23668 (United States)
Publication Date:
OSTI Identifier:
22280663
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1563; Journal Issue: 1; Conference: Workshop to explore physics opportunities with intense, polarized electron beams at 50-300 MeV, Cambridge, MA (United States), 14-16 Mar 2013; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCELERATOR FACILITIES; ALUMINIUM; APERTURES; BEAM MONITORING; BEAM MONITORS; BEAM TRANSPORT; CEBAF ACCELERATOR; ELECTRON BEAMS; FERMILAB ACCELERATOR; FIELD EMISSION; FREE ELECTRON LASERS; MEV RANGE; NEUTRONS; NIOBIUM; PHOTONS; RF SYSTEMS