Search

A new experiment to measure electric dipole moments (EDMs) of elementary particles, based on the Frequency Domain method, has been proposed for implementation at the NICA facility (JINR, Russia). EDM experiments in general, being measurement-of-polarization experiments, require long spin-coherence times at around 1,000 seconds. The FD method involves a further complication (well paid off in orders of precision) of switching the polarity of the guiding field as part of its CW-CCW injection procedure. This latter procedure necessitates a calibration process, during which the beam polarization axis n ¯ changes its orientation from the radial (used for the measurement) to the vertical (used for the calibration) direction. If this change occurs adiabatically, the beam particles’ spin-vectors follow the direction of the polarization axis — which undermines the calibration technique; however, concerns were raised as to whether violation of adiabaticity could damage spin-coherence. These concerns are addressed in the present investigation.

CERN Yellow Reports: Monographs Published by CERN; International audience; The proposed method exploits charged particles confined as a storage ring beam (proton, deuteron, possibly $^3$He) to search for an intrinsic electric dipole moment (EDM) aligned along the particle spin axis. Statistical sensitivities can approach $10^{29} e$ cm. The challenge will be to reduce systematic errors to similar levels. The ring will be adjusted to preserve the spin polarization, initially parallel to the particle velocity, for times in excess of 15 minutes. Large radial electric fields, acting through the EDM, will rotate the polarization. The slow rise in the vertical polarization component, detected through scattering from a target, signals the EDM. The project strategy is outlined. It foresees a step-wise plan, starting with ongoing COSY activities that demonstrate technical feasibility. Achievements to date include reduced polarization measurement errors, long horizontal-plane polarization lifetimes, and control of the polarization direction through feedback from the scattering measurements. The project continues with a proof-of-capability measurement (precursor experiment; first direct deuteron EDM measurement), an intermediate prototype ring (proof-of-principle; demonstrator for key technologies), and finally the high precision electric-field storage ring.

Geneva : CERN Yellow Reports: Monographs 22MB (2021). doi:10.23731/CYRM-2021-003, Published by CERN Yellow Reports: Monographs, Geneva

In this study, Co0,7Zn1,3W powders were synthesized and investigated at the microwave region. The solid-state reaction method and self-propagating high-temperature synthesis were used to production of the two kinds of hexaferrite powders. The high-frequency magnetic properties under temperature effect have been studied. It is show, that there is a nonlinear dependence on temperature within the 0 – +40 °C temperature range.

The purpose of the present work is the development of a method for searching the electric dipole moment (EDM) of the deuteron inside the storage ring environment using the frozen spin method. The 2D frozen spin method is a variation on the original frozen spin method proposed at Brookhaven National Laboratory, in which the beam polarisation vector freely precesses in the vertical plane. One distinguishing feature of the 2D frozen spin method, is that it uses the radial magnetic fields induced by the accelerator optical lattice's imperfections to drive the vertical plane precession. The net electric + magnetic dipole moment spin precession frequency is measured. The EDM estimator is constructed as the sum of the net frequency estimates in two cases: when the beam circulates clockwise (CW), and when it does counter-clockwise (CCW). For the deuteron, since the experiment is performed in a combined ring, the beam circulation direction change requires flipping the polarity of the guiding magnetic field. When this is done, the imperfection fields change their sign as well, and so does the magnetic dipole moment (MDM) component of the spin precession angular velocity vector. Therefore, theoretically, the MDM term cancels in the EDM estimator. The trick is to calibrate the MDM precession frequency with sufficient precision. For that purpose, the concept of the effective Lorentz factor was introduced. We try to prove that particles having equal values of the effective Lorentz factor have equal spin tunes (and invariant spin axis orientations as well), and therefore, by controlling a single parameter -- the effective Lorentz factor -- it is possible to calibrate the MDM component of the precession frequency. A special calibration procedure is numerically modelled, with the conclusion that it allows sufficiently precise MDM spin precession frequency reproduction. Three major systematic effects of spin dynamics have been analysed: 1) perturbations to the particle spin dynamics caused by betatron oscillations, 2) spin decoherence in the zero spin resonance (frozen spin) region, 3) properties of the machine imperfection MDM spin precession angular velocity. We conclude that the first systematic effect is negligible; analyse the sextupole field approach to suppressing spin decoherence, and find it effective; find that the imperfections systematic error is linear, but asymmetric with respect to the beam circulation direction, which is more motivation for using the effective Lorentz factor as the tool for calibrating the MDM spin precession frequency. Overall, we find the proposed method effective.

This project exploits charged particles confined as a storage ring beam (proton, deuteron, possibly $^3$He) to search for an intrinsic electric dipole moment (EDM, $\vec d$) aligned along the particle spin axis. Statistical sensitivities can approach $10^{-29}$~e$\cdot$cm. The challenge will be to reduce systematic errors to similar levels. The ring will be adjusted to preserve the spin polarization, initially parallel to the particle velocity, for times in excess of 15 minutes. Large radial electric fields, acting through the EDM, will rotate the polarization ($\vec d \times\vec E$). The slow rise in the vertical polarization component, detected through scattering from a target, signals the EDM. The project strategy is outlined. It foresees a step-wise plan, starting with ongoing COSY activities that demonstrate technical feasibility. Achievements to date include reduced polarization measurement errors, long horizontal-plane polarization lifetimes, and control of the polarization direction through feedback from the scattering measurements. The project continues with a proof-of-capability measurement (precursor experiment; first direct deuteron EDM measurement), an intermediate prototype ring (proof-of-principle; demonstrator for key technologies), and finally the high precision electric-field storage ring.

In this article we studied the prognosis of various schemes of reperfusion therapy and subsequent medical treatment during a year of observation in elderly and senile patients with ST elevation myocardial infarction. We examined 80 patients, 46 of them were elderly, and 34 were senile patients. Revealed that the combined endpoint (death, cardiovascular complications) between elderly patients (1 st grp) and senile patients (2 nd grp) who received thrombolytic therapy was less significant, and in patients without reperfusion therapy it was more significant in the second group.

A new method for searching for the electric dipole moment (EDM) of the deuteron and other nuclei is presented. When trying to measure the EDM in a storage ring environment, magnetic dipole moment (MDM) spin precession due to machine imperfections becomes the primary source of systematic error. The proposed method aims at providing a solution to the machine imperfection problemas well as circumventing the geometric phase error. The method is based on estimating the combined MDM + EDM spin precession frequency, in which the MDM contribution is due only to field imperfections. The MDM term is canceled in the final statistic by adding frequency estimates from cycles with counter-circulating beams. Spin precession rate depends on the particle’s effective Lorentz factor; the proposed method’s core feature is a procedure for equalizing the effective Lorentz factors of the clockwise and counter-clockwise circulating beams, thus enabling the cancelation.

Currently, the "Julich Electric Dipole moment Investigations" (JEDI) collaboration, together with present EDM experiments at the COSY ring, is developing the conceptual design of a ring specifically for the search for the deuteron electric dipole moment (dEDM). One of the main problems in the EDM study is the spin precession in the vertical plane caused by the non-ideal positioning of accelerator elements through the magnetic dipole moment (MDM). The idea of how to separate the EDM from MDM is based on measuring the spin tune in different processes and comparing the results. The high precision of the spin tune measurement is achieved by collecting huge amounts of data. The JEDI collaboration aims at detecting the EDM at a level better than 10−29 e cm, for which one requires a precision in the frequency estimate ~ 10−9 rad/sec. An estimate's statistical precision is conditional on the following factors: the total measurement time, determining the independent variable spread; measurement error; temporal modulation and spacing of sample points. In this paper we analyze the interplay between these factors, and estimate the best achievable precision under given conditions.

Based on the notion that the local dark-matter field of axions or axion-like particles (ALPs) in our Galaxy induces oscillating couplings to the spins of nucleons and nuclei (via the electric dipole moment of the latter and/or the paramagnetic axion-wind effect), we establish the feasibility of a new method to search for ALPs in storage rings. Based on previous work that allows us to maintain the in-plane polarization of a stored deuteron beam for a few hundred seconds, we performed a first proof-of-principle experiment at the Cooler Synchrotron COSY to scan momenta near 970 MeV/c. This entailed a scan of the spin precession frequency. At resonance between the spin precession frequency of deuterons and the ALP-induced EDM oscillation frequency there will be an accumulation of the polarization component out of the ring plane. Since the axion frequency is unknown, the momentum of the beam and consequently the spin precession frequency were ramped to search for a vertical polarization change that would occur when the resonance is crossed. At COSY, four beam bunches with different polarization directions were used to make sure that no resonance was missed because of the unknown relative phase between the polarization precession and the axion/ALP field. A frequency window of 1.5-kHz width around the spin precession frequency of 121 kHz was scanned. We describe the experimental procedure and a test of the methodology with the help of a radiofrequency Wien filter located on the COSY ring. No ALP resonance was observed. As a consequence an upper limit of the oscillating EDM component of the deuteron as well as its axion coupling constants are provided., 27 pages, 24 figures, 7 tables, 104 references