Project number: P07/03
Planned activity
Project Title: RAdon Removal and BAckground Characterisation for LIquid Scintillation Spectrometry at Gran Sasso National Laboratory
Group Leader: L. Kaihola: PerkinElmer Life and Analytical Sciences, Turku (Finland)
Researchers: L. Kaihola
Planned activity (filled by group leader):
PerkinElmer Life and Analytical Sciences/Wallac Oy, who makes ultra low background liquid scintillation spectrometers, is interested in experiments in Gran Sasso laboratory in order to quantitate background level of Wallac 1220 Quantulus LS spectrometer in the presence of minimal cosmic radiation flux. Much of the environmental gamma radiation is removed by instrument’s active anti-Compton guard detector. Quantulus has a sophisticated multi-channel analyser, which is controlled by logic commands. This MCA enables effective monitoring of many background signal components, even the rejected background events.
A series of test measurements at Gran Sasso We have been carried out with Dr. Wolfango Plastino using 1220 Quantulus liquid spectrometer to investigate the contribution of the environmental radiation to the background signal in this instrument. These investigations have been published [1],[2]. One of the important findings is that active anti-Compton detection improves C-14 background only by 8 % in Gran Sasso. This means that the contribution from environmental radiation is far smaller than on surface where the figure is 80 %. C-14 background is better in normal vials underground than in masked vials on surface. Another finding is the presence of radon in the current GS laboratory. Radon produces additional background particularly in tritium measurements, where air luminescence contributes in low channels.
An additional effort is needed to eliminate radon in the counting chamber. Elimination is possible by ventilation and shielding gas. Only removal of radon gives clean liquid scintillation background, which is necessary for the evaluation of the instrumental background components. Furthermore, absence of radon will ensure stable background, which is a necessary requirement for long counting periods of low activity liquid scintillation spectrometry
References
[1] Plastino, W., Kaihola, L., Bartolomei, P., Bella, F., Cosmic background reduction in the radiocarbon measurements by liquid scintillation spectrometry at the underground laboratory of Gran Sasso, Radiocarbon, 43 (2A), 157-161, 2001.
[2] Plastino, W., Kaihola, L., Surface and underground ultra low level liquid scintillation spectrometry, Radiocarbon, submitted. (presented at 18th International Radiocarbon Conference, 1-5 September 2003, Wellington, New Zealand).
Group Leader: L. Kaihola: PerkinElmer Life and Analytical Sciences, Turku (Finland)
Researchers: L. Kaihola
Planned activity (filled by group leader):
PerkinElmer Life and Analytical Sciences/Wallac Oy, who makes ultra low background liquid scintillation spectrometers, is interested in experiments in Gran Sasso laboratory in order to quantitate background level of Wallac 1220 Quantulus LS spectrometer in the presence of minimal cosmic radiation flux. Much of the environmental gamma radiation is removed by instrument’s active anti-Compton guard detector. Quantulus has a sophisticated multi-channel analyser, which is controlled by logic commands. This MCA enables effective monitoring of many background signal components, even the rejected background events.
A series of test measurements at Gran Sasso We have been carried out with Dr. Wolfango Plastino using 1220 Quantulus liquid spectrometer to investigate the contribution of the environmental radiation to the background signal in this instrument. These investigations have been published [1],[2]. One of the important findings is that active anti-Compton detection improves C-14 background only by 8 % in Gran Sasso. This means that the contribution from environmental radiation is far smaller than on surface where the figure is 80 %. C-14 background is better in normal vials underground than in masked vials on surface. Another finding is the presence of radon in the current GS laboratory. Radon produces additional background particularly in tritium measurements, where air luminescence contributes in low channels.
An additional effort is needed to eliminate radon in the counting chamber. Elimination is possible by ventilation and shielding gas. Only removal of radon gives clean liquid scintillation background, which is necessary for the evaluation of the instrumental background components. Furthermore, absence of radon will ensure stable background, which is a necessary requirement for long counting periods of low activity liquid scintillation spectrometry
References
[1] Plastino, W., Kaihola, L., Bartolomei, P., Bella, F., Cosmic background reduction in the radiocarbon measurements by liquid scintillation spectrometry at the underground laboratory of Gran Sasso, Radiocarbon, 43 (2A), 157-161, 2001.
[2] Plastino, W., Kaihola, L., Surface and underground ultra low level liquid scintillation spectrometry, Radiocarbon, submitted. (presented at 18th International Radiocarbon Conference, 1-5 September 2003, Wellington, New Zealand).