Search

Novel experimental techniques are required to make the next big leap in neutron electric dipole moment experimental sensitivity, both in terms of statistics and systematic error control. The nEDM experiment at the Spallation Neutron Source (nEDM@SNS) will implement the scheme of Golub & Lamoreaux [Phys. Rep., 237, 1 (1994)]. The unique properties of combining polarized ultracold neutrons, polarized 3He, and superfluid 4He will be exploited to provide a sensitivity to ∼ 10−28 e · cm. Our cryogenic apparatus will deploy two small (3 L) measurement cells with a high density of ultracold neutrons produced and spin analyzed in situ. The electric field strength, precession time, magnetic shielding, and detected UCN number will all be enhanced compared to previous room temperature Ramsey measurements. Our 3He co-magnetometer offers unique control of systematic effects, in particular the Bloch-Siegert induced false EDM. Furthermore, there will be two distinct measurement modes: free precession and dressed spin. This will provide an important self-check of our results. Following five years of “critical component demonstration,” our collaboration transitioned to a “large scale integration” phase in 2018. An overview of our measurement techniques, experimental design, and brief updates are described in these proceedings.

Cold antihydrogen has been produced at CERN (Amoretti et al. (Nature, 419, 456 (2002)), Gabrielse et al. (Phys. Rev. Lett. 89, 213401 (2002))), with the aim of performing a high-precision spectroscopic comparison with hydrogen as a test of the CPT symmetry. Hydrogen, a unique system used for the development of quantum mechanics and quantum electrodynamics, has been continuously used to produce high-precision tests of theories and measurements of fundamental constants and can lead to a very sensitive search for CPT violation. After the initial production of cold antihydrogen atoms by the ATHENA group, the ALPHA Collaboration (http://alpha.web.cem.ch/) has set forth on an experiment to trap and perform high-resolution laser spectroscopy on the 1S-2S transition of both atoms. In this contribution, we will review the motivations, goals, techniques, and recent developments towards this fundamental physics test. We present new discussion on predicted lineshapes for the 1S-2S spectroscopy of trapped atoms in a regime not discussed before. PACS Nos: 36.10.-k, 32.60.+i, 37.10.Gh Nous avons produit de l'anti-hydrogene an CERN (Amoretti et al. (Nature, 419, 456 (2002)), Gabrielse et al. (Phys. Rev. Lett. 89, 213401 (2002))), pour faire des comparaisons spectroscopiques de haute precision avec ''hydrogene dans le cadre d'un test de la symetrie CPT. L'hydrogene, qui a joue un role unique dans le developpement de la mecanique quantique et de 1'electrodynamique quantique, a ete utilise continuellement dans des tests de haute precision des theories et des mesures des constantes fondamentales et pent nous conduire a une recherche tres precise de la violation CPT. Apres que le groupe ATHENA ait produit 'anti-hydrogene froid, l'equipe ALPHA (http://alpha.web.cern.ch/) a developpe un montage pour pieger les deux types d' atome et faire des mesures de spectroscopie laser de haute precision des transitions 1S-2S dans les deux types d'atomes. Nous passons ici en revue les motivations, les buts, les techniques et les developpements recents de ce test fondamental en physique. Nous presentons de nouvelles idees sur la forme des lignes en spectroscopie 1S-2S pour des atomes pieges dans un regime qui n'a pas encore ete discute. [Traduit par la Redaction], I Introduction The very fundamental discrete symmetry of CPT, standing for the simultaneous operations of charge conjugation (C), parity inversion (P), and time reversal (T), is a base for quantum [...]

A novel low-temperature bolometric method has been devised and implemented for high-precision measurements of the microwave surface resistance of small single-crystal platelet samples having very low absorption, as a continuous function of frequency. The key to the success of this nonresonant method is the in situ use of a normal metal reference sample that calibrates the absolute rf field strength. The sample temperature can be controlled independently of the 1.2 K liquid-helium bath, allowing for measurements of the temperature evolution of the absorption. However, the sensitivity of the instrument decreases at higher temperatures, placing a limit on the useful temperature range. Using this method, the minimum detectable power at 1.3 K is 1.5 pW, corresponding to a surface resistance sensitivity of ≈1 μΩ for a typical 1 mm×1 mm platelet sample. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Describes a cavity perturbation technique for accurate measurement of radio frequency magnetic filing factors, which is especially relevant to cryogenic magnetic resonance experiments. Type I perturbations; Type II perturbations; Practical measurements.

Abstract: The ALPHA experiment has succeeded in trapping antihydrogen, a major milestone on the road to spectroscopic comparisons of antihydrogen with hydrogen. An annihilation vertex detector, which determines the time and position of antiproton annihilations, has been central to this achievement. This detector, an array of double-sided silicon microstrip detector modules arranged in three concentric cylindrical tiers, is sensitive to the passage of charged particles resulting from antiproton annihilation. This article describes the method used to reconstruct the annihilation location and to distinguish the annihilation signal from the cosmic ray background. Recent experimental results using this detector are outlined. [Copyright &y& Elsevier]