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Improved Isotopic Analysis With a Large Array of Gamma-Ray Microcalorimeters



Nikhil Jethava, Joel N. Ullom, Douglas A. Bennett, William B. Doriese, James A. Beall, Gene C. Hilton, Robert D. Horansky, Kent D. Irwin, Eric Sassi, Leila R. Vale, Minesh K. Bacrania, Andrew Hoover, P. J. Karpius, Michael W. Rabin, Clifford R. Rudy, Duc T. Vo


We present results from the largest array of gamma-ray microcalorimeters operated to date. The microcalorimeters consist of Mo/Cu transition-edge sensors with attached Sn absorbers. The detector array contains 66 pixels each with an active area 2.25 mm2 . Out of 66 pixels, 55 are active, and 31 were used to acquire a high statistics Pu gamma-ray spectrum. The energy resolution of the best 21 pixels was found to be 120 eV FWHM. The array is read out using time domain SQUID multiplexing. Here, we describe the multiplexing and present a high statistics Pu spectra. Because of the large collecting area of our array, the statistical error in the 240Pu line intensity is approximately 0.7%, which is comparable to the systematic error in a measurement with a 500 eV germanium sensor. Hence, we have reached an important threshold for demonstrating improved isotopic measurements with microcalorimeter sensors. With straightforward changes, we plan to achieve a resolution of about 50 eV FWHM with 256 multiplexed detectors. Finally, we present early estimates of on-chip heating within our sensor array.
IEEE Transactions on Nuclear Science


gamma-ray microcalorimeters, transition-edge sensors, SQUID multiplexing, high statistics Pu spectra, isotopic measurements, on-chip heating, sensor array


Jethava, N. , Ullom, J. , Bennett, D. , Doriese, W. , Beall, J. , Hilton, G. , Horansky, R. , Irwin, K. , Sassi, E. , Vale, L. , Bacrania, M. , Hoover, A. , , P. , Rabin, M. , Rudy, C. and Vo, D. (2009), Improved Isotopic Analysis With a Large Array of Gamma-Ray Microcalorimeters, IEEE Transactions on Nuclear Science, [online], (Accessed June 22, 2024)


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Created June 30, 2009, Updated June 23, 2020