Optimization of X-ray absorbers for TES microcalorimeters

Naoko Iyomoto; John E. Sadleir; Enectali Figueroa-Feliciano; Tarek Saab; Simon R. Bandler; Caroline A. Kilbourne; James A. Chervenak; Dorothy Talley; Fred M. Finkbeiner; Regis P. Brekosky; Mark A. Lindeman; Richard L. Kelley; Frederick Scott Porter; Kevin R. Boyce

doi:10.1117/12.552063

29 September 2004 Optimization of x-ray absorbers for TES microcalorimeters

Naoko Iyomoto, John E. Sadleir, Enectali Figueroa-Feliciano, Tarek Saab, Simon R. Bandler, Caroline A. Kilbourne, James A. Chervenak, Dorothy Talley, Fred M. Finkbeiner, Regis P. Brekosky, Mark A. Lindeman, Richard L. Kelley, Frederick Scott Porter, Kevin R. Boyce

Author Affiliations +

Proceedings Volume 5501, High-Energy Detectors in Astronomy; (2004) https://doi.org/10.1117/12.552063
Event: SPIE Astronomical Telescopes + Instrumentation, 2004, Glasgow, United Kingdom

Abstract

We have investigated the thermal, electrical, and structural properties of Bi and BiCu films that are being developed as X-ray absorbers for transition-edge sensor (TES) microcalorimeter arrays for imaging X-ray spectroscopy. Bi could be an ideal material for an X-ray absorber due to its high X-ray stopping power and low specific heat capacity, but it has a low thermal conductivity, which can result in position dependence of the pulses in the absorber. In order to improve the thermal conductivity, we added Cu layers in between the Bi layers. We measured electrical and thermal conductivities of the films around 0.1 K, the operating temperature of the TES calorimeter, to examine the films and to determine the optimal thickness of the Cu layer. From the electrical conductivity measurements, we found that the Cu is more resistive on the Bi than on a Si substrate. Together with a SEM picture of the Bi surface, we concluded that the rough surface of the Bi film makes the Cu layer resistive when the Cu layer is not thick enough to fill in the roughness. From the thermal conductivity measurements, we determined the thermal diffusion constant to be 2 x 10³ μm²μs^-1 in a film that consists of 2.25 μm of Bi and 0.1 μm of Cu. We measured the position dependence in the film and found that its thermal diffusion constant is too low to get good energy resolution, because of the resistive Cu layer and/or possibly a very high heat capacity of our Bi films. We show plans to improve the thermal diffusion constant in our BiCu absorber.

Citation Download Citation

Naoko Iyomoto, John E. Sadleir, Enectali Figueroa-Feliciano, Tarek Saab, Simon R. Bandler, Caroline A. Kilbourne, James A. Chervenak, Dorothy Talley, Fred M. Finkbeiner, Regis P. Brekosky, Mark A. Lindeman, Richard L. Kelley, Frederick Scott Porter, and Kevin R. Boyce "Optimization of x-ray absorbers for TES microcalorimeters", Proc. SPIE 5501, High-Energy Detectors in Astronomy, (29 September 2004); https://doi.org/10.1117/12.552063

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available