The concept of calorimetric low temperature detectors (CLTDs), which is based on the collection of phonons, provides considerable advantage over conventional heavy ion detectors, based on charge or photon collection, with respect to basic detector properties such as energy resolution, detection efficiency, energy threshold, radiation hardness, etc. [1]. Such detectors have therefore the potential to become powerful tools for various applications in AMS, especially for the detection of very slow heavy ions.
The operating principle of CLTDs will be briefly discussed, and the design of dedicated detectors for AMS applications and their performance for heavy ion detection in the energy range typically used for AMS are displayed. Excellent relative energy resolutions of the order of 2 – 5 x 10-3 for heavy ions such as 209Bi and 238U in the energy range of 0.1 – 10 MeV/amu, and a perfect energy linearity with no indication of a pulse height defect were obtained.
CLTDs with such performance were recently applied for the first time in an AMS experiment performed at the VERA facility at Vienna. Replacing a conventionally used detection system by a CLTD allowed to substantially increase the detection efficiency, at similar background reduction. Results concerning the 236U/238U isotope ratio for several samples of natural uranium are presented. Due to the high sensitivity achieved, a value of 236U/238U = 6.1 x 10-12 could be obtained, representing the smallest 236U/238U isotope ratio measured up to date.
[1] P. Egelhof and S. Kraft-Bermuth in Cryogenic Particle Detection, Topics Appl. Phys. 99, 469–500 (2005), Springer-Verlag Berlin Heidelberg
See more of Poster Session II
See more of The 10th International Conference on Accelerator Mass Spectrometry (September 5-10, 2005)