Calibration and performance of a secondary emission chamber as a beam intensity monitor

Conference · Mon Mar 28 00:00:00 EDT 2011

OSTI ID:1017405

Sivertz, M; Chiang, I-H; Rusek, A

We report on a study of the behavior of a secondary emission chamber (SEC). We show the dependence of the SEC signal on the charge and velocity of the primary beam for beams of protons, and heavy ions including Helium, Neon, Chlorine and Iron. We fill the SEC with a selection of different gases including Hydrogen, Helium, Nitrogen, Argon, and air, studying the SEC response when it is acting as an ion chamber. We also investigate the behavior of the SEC at intermediate pressures between 10{sup -8} torr and atmospheric pressure. The SEC uses thin conducting foils as the source and collector of electrons in a vacuum chamber. When charged particles traverse the vacuum chamber, they pass through a series of thin conducting foils, alternating anode and cathode. Ionization produced in the cathode foils travels across the intervening gap due to an applied high voltage and is collected on the anode foils. Electron production is very inefficient because most of the ionization in the foils remains trapped within the foil due to the short range of most delta-rays and the work function of the foil. It is this inefficiency that allows the SEC to operate at high dose rates and short pulse duration where the standard ion chambers cannot function reliably. The SEC was placed in the NSRL ion beam to receive a variety of heavy ion beams under different beam conditions. We used these ion beams to study the response of the SEC to different species of heavy ion, comparing with proton beams. We studied the response to beam of different energies, and as a function of different counting rate. We compared the behaviour of the SEC when operating under positive and negative high voltage. The SEC can operate as an ion chamber if it is filled with gas. We measured the response of the SEC when filled with a variety of gases, from Hydrogen to Helium, Nitrogen, Argon and air. The performance of the SEC as an ion chamber is compared with the standard NSRL ion chamber, QC3. By evacuating the SEC and filling it with Nitrogen through an adjustable leak valve, we were able to measure the response of the SEC to beam as a function of gas pressure. Many interesting features of the SEC were revealed in these tests.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States)
• Sponsoring Organization: DOE - OFFICE OF SCIENCE
• DOE Contract Number: DE-AC02-98CH10886
• OSTI ID: 1017405
• Report Number(s): BNL-95054-2011-CP; R&D Project: KBCH139; 08272; KB0202011; TRN: US1103243
• Resource Relation: Conference: 2011 Particle Accelerator Conference (PAC'11); New York, NY; 20110328 through 20110401
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
43 PARTICLE ACCELERATORS
ACCELERATORS
ANODES
ARGON
ATMOSPHERIC PRESSURE
CALIBRATION
CATHODES
CHARGED PARTICLES
CHLORINE
COUNTING RATES
DELTA RAYS
DOSE RATES
ELECTRONS
GASES
HEAVY IONS
HELIUM
HYDROGEN
ION BEAMS
IONIZATION
IRON
MONITORS
NEON
NITROGEN
PROTON BEAMS
PROTONS
SECONDARY EMISSION
WORK FUNCTIONS