1,720,984 research outputs found
Topics on electron,neutrino and axion scattering
No full textThesis: S.M., Massachusetts Institute of Technology, Department of Physics, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from PDF version of thesis.Includes bibliographical references (pages 61-64).Under the broad topic of scattering, in this thesis we particularly investigate Lorentz invariance using Compton Scattering at the Compton Polarimeter located in Hall-C at Thomas Jefferson National Accelerator Facility. The Mississippi State Axion Search, an axion search experiment which uses light shining through a wall technique is described in detail, including its instrumentation, initial tests and future impact. Furthermore, a novel method of detection of solar anti-neutrinos based on coherent neutrino scattering is described. Additionally, on the instrumentation side, development of a multi-purpose beam instrument based on synchrotron light to measure the electron beam polarization, beam profile and intensity at the future Electron Ion Collider is presented.by Prajwal Mohanmurthy.S.M
Characterization of PSI nEDM apparatus: T1, T*2, and UCN storage lifetime
No full textThe neutron electric dipole moment (nEDM) experiment, located at the Paul Scherrer Institute (PSI), employs the Ramsey technique of separated oscillating fields, at room temperature, to search for a permanent EDM in the neutron. Neutrons with very low energy are produced in the PSI ultracold neutron (UCN) source, which are polarized by allowing them to pass through a 5 T strong magnetic field produced by a superconducting magnet. The UCNs are then stored in a chamber, where they are subject to the Ramsey technique. Manipulation of magnetization of the ensemble of stored UCNs is governed by Bloch equations, which describe the Larmor precession under the influence of a magnetic field, and involve two channels of depolarization; the transverse depolarization and the longitudinal depolarization. The time constants for longitudinal and transverse depolarization, T1 and T*2, respectively, were measured in the PSI nEDM apparatus at the beginning of the nEDM data taking schedule. T1 and T*2 play an important role in optimizing the period of free spin-precession in the Ramsey technique. We report the relaxation time constants as T1=(5770\pm420) s and T*2=(1550\pm22) s, for the UCNs from the PSI UCN source in the PSI nEDM apparatus. These values of T1 and T*2 are consistent with values reported in EPJ Web Conf. 219, 02001 (2019)
A novel spin-light polarimeter for the Electron Ion Collider
Full text linkA novel precision polarimeter will go a long way in satisfying the requirements of the precision experiments being planned for a future facility such as the Electron Ion Collider. A polarimeter based on the asymmetry in the spacial distribution of the spin light component of synchrotron radiation will make for a fine addition to the existing conventional Møller and Compton polarimeters. The spin light polarimeter consists of a set of wriggler magnet along the beam that generate synchrotron radiation. The spacial distribution of synchrotron radiation will be measured by an ionization chamber after being collimated. The up-down spacial asymmetry in the transverse plane is used to quantify the polarization of the beam. As a part of the design process, firstly, a rough calculation was drawn out to establish the validity of such an idea. Secondly, the fringe fields of the wriggler magnet was simulated using a 2-D magnetic field simulation toolkit called Poisson Superfish, which is maintained by Los Alamos National Laboratory. This was used to account for beam motion effects and the corresponding correlations were show to be negligible. Lastly, a full fledged GEANT-4 simulation was built to study the response time of the ionization chamber. Currently, this GEANT-4 simulation is being analyzed for variety of effects that may hinder precision polarimetry
Interpretations of Quantum Mechanics: A General Purview
Full text linkQuantum mechanics revolutionized physics in early 20th century and lead to one of the two field theories, the standard model, which is a crowing achievement of our contemporary times. However, paradoxes within the quantum mechanics, were recognized early on. These paradoxes have paved way to multiple interpretations of quantum mechanics over the century. These interpretations do not particularly affect the validity of the empirically established observations and measurements. We will attempt to introduce a few major interpretations of quantum mechanics and present their advantages and disadvantages in a very limited fashion. Though most interpretations do not tend themselves to experimental tests, it is possible that many of the interpretations are mere differing versions of the same objective truth, while some interpretations that do tend themselves to experimental test, beg further exploration of the foundations of quantum mechanics
A Search for Mirror Neutron Oscillation Using the nEDM Apparatus at PSI: Details about computing the mean time between collisions and extraction of the limit on the n-n' oscillation time
No full textBaryon number violation is a key ingredient of baryogenesis. Since the famous parity violation paper of Lee and Yang, it has been hypothesized that there could also be a parity conjugated copy, in the context of the weak interaction, of the standard model particles. The existence of such a mirror universe has specific testable implications, especially in the domain of neutral particle oscillation, viz. the baryon number violating neutron to mirror-neutron (n-n')oscillation. It was shown that such n-n' oscillations could happen rapidly with an oscillation time as small as a second. Consequently, there were many experiments which searched for n-n' oscillation, but which have so far reported finding no evidence of n-n' oscillation. Even though the experiments report having found no evidence of n-n' oscillation, reanalysis of some of these results have identified three particular anomalies which could point to the detection of n-n' oscillation. All but one of these efforts were conducted at the Institut Laue-Langevin in Grenoble, France, with the most recent search having been conducted at the Paul Scherrer Institute in Villigen, Switzerland. The results from this latest effort were announced in Phys. Lett. B 812, 135993 (2021). This search for n-n' oscillation involved measuring the number of neutrons after storage for a time period under the influence of zero magnetic field or a finite magnetic field. The neutron counting measurables were combined with the mean time between collisions of the stored Ultra Cold Neutrons (UCNs) to yield constraints on the n-n' oscillation time constant. In this paper, additional details regarding the analysis, i.e. the method of estimating mean time between collisions, as well as the numerical technique of extracting the constraint upon the n-n' oscillation time constant from the neutron counting measurables, is described. We obtained (t^*_s=180s)=0.0628(27)s, (t^*_s=380s)=0.0756(30)s, and (/)(t^*_s=180s)=0.104(10)s, (/)(t^*_s=380s)=0.120(10)s.SERI-FCS award # 2015.0594 and Sigma Xi grants # G2017100190747806 and # G201910019074780
False EDM effects in PSI nEDM: Leakage Currents and Background Asymmetries
No full textThe Paul Scherrer Institute Neutron Electric Dipole Moment (PSI nEDM) experiment is a room temperature experiment using the Ramsey technique of separated oscillating fields to search for a permanent electric dipole moment in neutrons. The PSI nEDM experiment achieved a statistical sensitivity of d_n < 1.1 * 10^{-26} e.cm using data collected from 2015 to 2016.
The magnetic field produced by currents flowing near the precession chamber couple to the spin of the stored neutrons. Currents which are correlated with the electric field may induce a false measurable EDM. Candidates
for currents which are correlated with high voltage are leakage currents originating from the high voltage system used to apply a strong electric field to the stored neutrons. A study using finite element analysis of the possible pathways taken by the leakage
currents is discussed. Similarly, background neutron counts may also lead to false EDM signals. But such backgrounds would also need to be correlated with the neutron spin state, high voltage state, LF signal, and spin-flipper states.
We present a study here which constrains the false EDMs arising from such leakage currents to d^(False)_{n/Hg} < 4*10^{-28}
e.cm, and from background asymmetries to d^(False)_{n-Backgrounds} < 3.6*10^{-65}
e.cm.SERI-FCS award # 2015.0594 and Sigma Xi grants # G2017100190747806 and # G2019100190747806
Identifying ideal nuclei in which to search for CP violating moments: Necessity to populate nuclear levels and characterize their nuclear deformation
Full text linkNew sources of CP violation, beyond the known sources in the standard model (SM) via the CKM matrix, are required to explain the baryon asymmetry of the universe. Measurement of P,T violating moments, such as the electric dipole moment (EDM) or the magnetic quadrupole moment (MQM), of sub-atomic particles like the neutron or the electron as well as of atoms, serves as powerful tools with which to probe sources of CP violation. Quadrupole and octupole deformation of nuclei can significantly enhance the atomic EDM by many orders of magnitude compared to that with a spherical nucleus. In this white paper, we identify deformed isotopes in which to measure an EDM or an MQM. Furthermore, we also clearly identify a subset of these isotopes where measurements involving characterization of their level scheme and nuclear deformation parameters are necessary. (A section in the low energy white paper of the 2022 NSAC Long Range Planning exercise.)This work was sponsored by DOE grant #DE-SC0014448 and Ivy+ exchange program
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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