Speaker
Description
The advent of quantum sensing x-ray microcalorimeters such as Transition Edge Sensors (TESs) [1] has created exciting new opportunities to push the limits of precision physics in the hard x-ray domain. Thanks to the factor of 50 improvement in energy resolution offered by TESs over high-purity germanium [2, 3], and their high efficiency compared to crystal spectrometers [4], anti-protonic atom x-ray spectroscopy has entered a new era compared to the previous generation of experiments. The PAX project (anti-Protonic Atom X-ray spectroscopy) will employ a next-generation TES detector for spectroscopy of transitions between circular Rydberg states in antiprotonic atoms to establish new benchmarks for bound-state QED at field strengths well beyond the Schwinger limit with a precision of $10^{-5}$ in the few hundred keV regime [5]. Details of the PAX experiment at the CERN’s ELENA facility [6,7] and preliminary results from the test beam conducted in 2025 including unique challenges for detector development related to annihilation and electromagnetic background will be discussed.
[1] Review of superconducting transition-edge sensors for x-ray and gamma-ray spectroscopy, J.N. Ullom and D.A. Bennett. Supercond. Sci. Tech. 28, 084003 (2015).
[2] Recent Results on Antiprotonic Atoms using a Cyclotron Trap at LEAR, L.M. Simons. Physica Scripta 1988, 90 (1988).
[3] X-ray transitions from antiprotonic noble gases, D. Gotta, K. Rashid, B. Fricke, P. Indelicato and L.M. Simons. Eur. Phys. J D 47, 11-26 (2008).
[4] Balmer a transitions in antiprotonic hydrogen and deuterium, D. Gotta, D.F. Anagnostopoulos, M. Augsburger, G. Borchert, C. Castelli, D. Chatellard, J.P. Egger, P. El-Khoury, H. Gorke, P. Hauser, P. Indelicato, K. Kirch, S. Lenz, T. Siems and L.M. Simons. Nucl. Phys. A 660, 283-321 (1999).
[5] Testing Quantum Electrodynamics with Exotic Atoms, N. Paul, G. Bian, T. Azuma, S. Okada and P. Indelicato. Phys. Rev. Lett. 126, 173001 (2021).
[6] The ELENA facility, W. Bartmann, P. Belochitskii, H. Breuker, F. Butin, C. Carli, T. Eriksson, W. Oelert, R. Ostojic, S. Pasinelli and G. Tranquille. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 376, 20170266 (2018).
[7] Towards Precision Spectroscopy of Antiprotonic Atoms for Probing Strong-field QED, Gonçalo Baptista, Shikha Rathi, Michael Roosa, Quentin Senetaire, Jonas Sommerfeldt, Toshiyuki Azuma, Daniel Becker, Francois Butin, Ofir Eizenberg, Joseph Fowler, Hiroyuki Fujioka, Davide Gamba, Nabil Garroum, Mauro Guerra, Tadashi Hashimoto, Takashi Higuchi, Paul Indelicato, Jorge Machado, Kelsey Morgan, Francois Nez, Jason Nobles, Ben Ohayon, Shinji Okada, Daniel Schmidt, Daniel Swetz, Joel Ullom, Pauline Yzombard, Marco Zito, Nancy Paul. Proceedings of Science: In submission; arXiv:2501.08893
