- Physical Review Journals
All JournalsPhysics Magazine
Access Provided by Xinjiang University

Physical Review D

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Open Access
  • Access by Xinjiang University

Probing internal conversion and dark-matter-induced deexcitation of Ta180m with a γ-ray TES array

A. Gando1,2, K. Ichimura1, K. Ishidoshiro1, T. Kikuchi3, T. Kishimoto4, A. Takeuchi1, R. Sato5, and R. Smith3

PDF

Phys. Rev. D 113, 052007 – Published 18 March, 2026

DOI: https://doi.org/10.1103/7sfd-b8gm

Abstract

We propose and evaluate a source-equals-detector search for the deexcitation of the long-lived isomer Ta180m in natural tantalum (Ta), using a γ-ray transition-edge-sensor (TES) array. Two capabilities absent in conventional high-purity germanium (HPGe) searches are exploited: (i) near-unity containment of low-energy secondaries [internal-conversion (IC) electrons and characteristic x-rays] and of the nuclear recoil, enabling a calorimetric, event-by-event measurement of the total deposited energy in the absorber; and (ii) a delayed-coincidence tag using the subsequent Ta180 electron-capture (EC) decay to Hf180. We evaluate the 3σ discovery reach for IC and for dark-matter (DM)-induced deexcitation in two benchmark scenarios: a strongly interacting DM subcomponent and inelastic DM with off diagonal couplings. Using a background model based on intrinsic radioactivity in the Ta absorber and realistic detector performance, we show that arrays with NTES=256 and 1,000 pixels can reach the theoretically expected IC half-life within 2.6 yr and 0.66 yr, respectively. For an array with NTES=104 and a five-year exposure, the projected sensitivity to DM-induced de-excitation surpasses limits inferred from HPGe nonobservations of Ta180m and probes regions of parameter space not covered by current direct-detection experiments.

View figure in article

Physics Subject Headings (PhySH)

Article Text

References (30)

  1. N. Auerbach and V. Zelevinsky, AIP Conf. Proc. 1912, 020002 (2017).
  2. H. Ejiri and T. Shima, J. Phys. G 44, 065101 (2017).
  3. E. R. Bauminger and S. G. Cohen, Phys. Rev. 110, 953 (1958).
  4. T. B. Ryves, J. Phys. G 6, 763 (1980).
  5. J. B. Cumming and D. E. Alburger, Phys. Rev. C 31, 1494 (1985).
  6. M. Hult, J. Gasparro, G. Marissens, P. Lindahl, U. Watjen, P. N. Johnston, C. Wagemans, and M. Kohler, Phys. Rev. C 74, 054311 (2006).
  7. B. Lehnert, M. Hult, G. Lutter, and K. Zuber, Phys. Rev. C 95, 044306 (2017).
  8. I. J. Arnquist et al. (Majorana), Phys. Rev. Lett. 131, 152501 (2023).
  9. R. Cerroni, S. Dell’Oro, A. Formicola, S. Ghislandi, L. Ioannucci, M. Laubenstein, B. Lehnert, S. S. Nagorny, S. Nisi, and L. Pagnanini, Eur. Phys. J. C 83, 925 (2023).
  10. M. Pospelov, S. Rajendran, and H. Ramani, Phys. Rev. D 101, 055001 (2020).
  11. M. V. Smirnov, G. Yang, Y. N. Novikov, J. D. Vergados, and D. Bonatsos, Nucl. Phys. B1005, 116594 (2024).
  12. H. Ejiri and T. Shima, J. Phys. G 44, 065101 (2017).
  13. P. Mohr, F. Kaeppeler, and R. Gallino, Phys. Rev. C 75, 012802 (2007).
  14. T. Hayakawa, P. Mohr, T. Kajino, S. Chiba, and G. J. Mathews, Phys. Rev. C 82, 058801 (2010).
  15. L. Roberti, M. Pignatari, A. Psaltis, A. Sieverding, P. Mohr, Z. Fülöp, and M. Lugaro, Astron. Astrophys. 677, A22 (2023).
  16. K. L. Malatji, M. Wiedeking, S. Goriely et al., Phys. Lett. B 791, 403 (2019).
  17. D. Belic et al., Phys. Rev. C 65, 035801 (2002).
  18. D. Tucker-Smith and N. Weiner, Phys. Rev. D 64, 043502 (2001).
  19. B. Lehnert, H. Ramani, M. Hult, G. Lutter, M. Pospelov, S. Rajendran, and K. Zuber, Phys. Rev. Lett. 124, 181802 (2020).
  20. T. Irimatsugawa, S. Hatakeyama, M. Ohno, H. Takahashi, C. Otani, and T. Maekawa, IEEE Trans. Appl. Supercond. 25, 1 (2015).
  21. M. Ohno, T. Irimatsugawa, H. Takahashi, C. Otani, T. Yasumune, K. Takasaki, C. Ito, T. Ohnishi, S.-i. Koyama, S. Hatakeyama et al., IEICE Trans. Electron. 100, 283 (2017).
  22. T. Kikuchi, G. Fujii, R. Hayakawa, R. Smith, F. Hirayama, Y. Sato, S. Kohjiro, M. Ukibe, M. Ohno, A. Sato, and H. Yamamori, Appl. Phys. Lett. 119, 222602 (2021).
  23. S. Agostinelli et al., Nucl. Instrum. Methods Phys. Res., Sect. A 506, 250 (2003).
  24. J. Allison et al., IEEE Trans. Nucl. Sci. 53, 270 (2006).
  25. J. Allison et al., Nucl. Instrum. Methods Phys. Res., Sect. A 835, 186 (2016).
  26. E. A. McCutchan, Nucl. Data Sheets 126, 151 (2015).
  27. M. Agostini, G. Benato, and J. Detwiler, Phys. Rev. D 96, 053001 (2017).
  28. G. Cowan, K. Cranmer, E. Gross, and O. Vitells, Eur. Phys. J. C 71, 1554 (2011); 73, 2501(E) (2013).
  29. J. Bramante, P. J. Fox, G. D. Kribs, and A. Martin, Phys. Rev. D 94, 115026 (2016).
  30. K. Ichimura et al., Prog. Theor. Exp. Phys. 2023, 123H01 (2023).

Outline

Information

Phys. Rev. D 113, 052007– Published 18 March, 2026
  • Received 28 December 2025
  • Accepted 18 February 2026
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation