Experimental SiteThe initial proton beam for PIF is delivered from the PROSCAN accelerator with the help of the primary energy degrader. This arrangement allows setting the initial beam energy from 230 MeV down to 72 MeV. The beam is subsequently guided to the Experimental Area where PIF facility is located. Having energy of the beam degraded directly after accelerator exit causes also its intensity reduction. Additional safety reasons put the maximum beam intensity in the PIF area up to 2 nA for energies above 200 MeV, 5 nA for energies from 100 MeV to 200 MeV and 10 nA for energies below 100 MeV. As PROSCAN accelerator serves mainly for cancer treatment with its three GANTRY stations (GANTRY3 under construction behind PIF area) and OPTIS2 facility, most of PIF exposures are conducted during weekends and short night-shifts. The PIF experimental area is located in the PROSCAN accelerator Hall as showed in the Figure 1 below.
Figure 1. PIF-PROSCAN Hall with the PIF Experimental Area.
PIF area with the PIF facility is equipped with the beam-line elements and test arrangement as showed below (Photo 1).
Photo 1. PIF area downstream view with the last quadrupole magnets, beam monitors and PIF station. One can see the XY-table with beam collimator.
- Initial proton energies: 230, 200, 150, 100 and 72 MeV (can be modified if requested)
- Energies available using the PIF degrader: quasi continuously from 6 MeV up to 230 MeV
- Energy straggling for the initial beam energy of 72 MeV: e.g. FWHM=2.4 MeV at 42.0 MeV, FWHM=5.6 MeV at 13.3 MeV.
- Maximum beam intensity at 230 MeV: 2 nA (at 72 MeV ca. 5 nA effectively)
- Maximum flux at 230 MeV for the focused beam: ~ 2E9 protons/sec/cm2
- Beam profiles are of Gaussian-form with standard (typical): FWHM=10 cm
- Irradiations take place in air
- The maximum diameter of the irradiated area: 9 cm
- The accuracy of the flux/dose determination: 5%
- Neutron background: less than 1E-4 neutrons/proton/cm2
- Irradiations, devices and sample positioning are supervised by the computer
- Sample mounting frame 25 x 25 cm2 (SEU and HIF facilities compatible) is attached to the XY table
- Data acquisition system allows automatic runs with user pre-defined irradiation criteria
Experimental arrangementThe PIF experimental set-up consists of the local PIF energy degrader, beam collimating and monitoring devices (Photo 2).
Photo 2. PIF arrangement with the ionization chamber, energy degrader and wire chamber.
Movable XY table with the sample holder (see Photo 3) enables easy mounting of the user's device under test (DUT) on the beam.
Photo 3. PIF arrangement rear view with the XY-table. One can see its movable arm and DUT sample holder.
The laser mounted downstream from the XY table allows centering the DUT and monitoring its position (see Photo 4).
Photo 4. PIF area downstream view with the laser for sample centering and the beam dump.
Irradiations are usually carried out in air. According to the experience and user requirements, the monitor detectors are selected for each experiment individually: ionization chambers, Si-detectors, plastic scintillators. In addition, the gamma and neutron dosimetry is routinely performed (see Photo 5 below). If needed the temperature, air pressure and humidity data are also available upon request.
Photo 5. PIF area neutron and gamma dosimeters.
Schematic view of the experimental hall from the point of view of beam-lines and area locations is shown in Figure below:
Figure 2. PROSCAN Hall, accelerator, beam-lines and tests areas. PIF site is marked as ‘EXP.’.
Exposure control and dosimetryThe irradiation is controlled from the experimental barrack located on top of the PIF area (see Photo 6 below).
Photo 6. PIF operator table in the barrack.
Beam flux values are monitored through a set of counters and a PC-based data acquisition system. The system monitors proton flux and dose rate, calculates the total deposited dose and controls the position of the sample as well as beam focus parameters. It also allows for setting the beam energy with the help of the PIF local energy degrader. This makes it possible to perform fully automated irradiations with arbitrary proton spectra.
Photo 7. One of the users tables.
The experimenters have for their use and needs of their data test setup the second part of the PIF barrack as seen on the Photo above. Standard laboratory and electronic equipments is also available.
-- Main.WojtekHajdas - 05 Nov 2015