Project number: P01/03
Status report (October 2003)
Project Title: Proton induced gamma background in gas target systems
Group Leader: Zs. Fülöp
Researchers: Z. Fulop, E. Somorjai, G. Gyurky
Delivered access (filled by TARI administration): 48 man-days
Status report (filled by group leader):
In order to study the origin and intensity of beam induced background in the gas target system at LUNA-II we have installed a high efficiency HPGE gamma detector at 90 degrees respected the beamline. We have systematically tested the system under different conditions, i.e. using Nitrogen and Helium gas as targets under 1, 2 and 5 mbar pressures using 100-200 keV bombarding proton energies.
As a result we have identified two main sources of beam induced gamma background:
1. Calorimeter surface
2. Last aperture of gas target system
The position determination was partly done by investigating the Doppler shift of the residual gamma radiation.
· In case 1 the surface is contaminated by 12,13C and 2H, these contaminations are most probably due to fractionated oil remnants from the high power pumping system.
· In case 2 11B was identified in the Brass collimator.
As a solution to the above problems we recommend not to run the gas target system without target gas for a prolonged period, and change the Brass collimator to a Copper one.
However, because the LUNA-II accelerator had to be stopped for accelerator tube maintenance we could not test our results in the given period with the high efficiency BGO system. These tests are very important, since the 14N(p,g)15O astrophysical reaction will be studied by the BGO system.
Future programs (filled by group leader):
· Background tests with the segmented 4π BGO detector array
· Verification of Copper collimator material
· Feasibility study of 14N(p,g)15O with the upgraded setup
Group Leader: Zs. Fülöp
Researchers: Z. Fulop, E. Somorjai, G. Gyurky
Delivered access (filled by TARI administration): 48 man-days
Status report (filled by group leader):
In order to study the origin and intensity of beam induced background in the gas target system at LUNA-II we have installed a high efficiency HPGE gamma detector at 90 degrees respected the beamline. We have systematically tested the system under different conditions, i.e. using Nitrogen and Helium gas as targets under 1, 2 and 5 mbar pressures using 100-200 keV bombarding proton energies.
As a result we have identified two main sources of beam induced gamma background:
1. Calorimeter surface
2. Last aperture of gas target system
The position determination was partly done by investigating the Doppler shift of the residual gamma radiation.
· In case 1 the surface is contaminated by 12,13C and 2H, these contaminations are most probably due to fractionated oil remnants from the high power pumping system.
· In case 2 11B was identified in the Brass collimator.
As a solution to the above problems we recommend not to run the gas target system without target gas for a prolonged period, and change the Brass collimator to a Copper one.
However, because the LUNA-II accelerator had to be stopped for accelerator tube maintenance we could not test our results in the given period with the high efficiency BGO system. These tests are very important, since the 14N(p,g)15O astrophysical reaction will be studied by the BGO system.
Future programs (filled by group leader):
· Background tests with the segmented 4π BGO detector array
· Verification of Copper collimator material
· Feasibility study of 14N(p,g)15O with the upgraded setup