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
3
He, and superfluid
4
He 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
3
He 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.
PHENIX has measured the centrality dependence of charged hadron p(T) spectra from Au +An collisions at root(s)NN = 130 GeV The truncated mean p(T) decreases with centrality for p(T) > 2 GeV/c, ...indicating an apparent reduction of the contribution from hard scattering to high p(T) hadrdn production. For central collisions the yield at high p(T) is shown to be suppressed compared to binary nucleon-nucleon collision scaling of p + p, data. This suppression is monotonically increasing with centrality, but most of the change occurs below 30% centrality, i.e., for collisions with less than similar to140 participating nucleons. The observed p(T) and centrality dependence is consistent with the particle production predicted by models including hard scattering and subsequent energy loss of the scattered partons in the dense matter created in the collisions. (C) 2003 Published by Elsevier Science B.V.
A system for collecting the scintillation light produced by the capture process of ultra-cold neutrons (UCN) on polarized \(^{3}\)He is discussed and results from simulations of its performance are ...presented. This system will be implemented in nEDM@SNS, the experiment searching for the neutron electric dipole moment (nEDM) at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Simulation results show that the light collection system collects on average 17 photoelectrons per UCN-\(^{3}\)He capture event (sufficient to generate a robust signal), reconstructs the event location in the beam direction to approximately 3 cm accuracy, detects capture events with a high and spatially uniform efficiency (0.95 with 1% variation), and rejects greater than 50% of beta decay background events.
Neutron beta decay is one of the most fundamental processes in nuclear physics and provides sensitive means to uncover the details of the weak interaction. Neutron beta decay can evaluate the ratio ...of axial-vector to vector coupling constants in the standard model, \(\lambda = g_A / g_V\), through multiple decay correlations. The Nab experiment will carry out measurements of the electron-neutrino correlation parameter \(a\) with a precision of \(\delta a / a = 10^{-3}\) and the Fierz interference term \(b\) to \(\delta b = 3\times10^{-3}\) in unpolarized free neutron beta decay. These results, along with a more precise measurement of the neutron lifetime, aim to deliver an independent determination of the ratio \(\lambda\) with a precision of \(\delta \lambda / \lambda = 0.03\%\) that will allow an evaluation of \(V_{ud}\) and sensitively test CKM unitarity, independent of nuclear models. Nab utilizes a novel, long asymmetric spectrometer that guides the decay electron and proton to two large area silicon detectors in order to precisely determine the electron energy and an estimation of the proton momentum from the proton time of flight. The Nab spectrometer is being commissioned at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source at Oak Ridge National Lab. We present an overview of the Nab experiment and recent updates on the spectrometer, analysis, and systematic effects.
In this article we describe the photon detection readout electronics for the nEDM@SNS experiment. The chosen "photon counting" architecture, which utilizes high-efficiency silicon photomultipliers ...(SiPMs) and is appropriate for low-light applications, allows the use of a relatively high SiPM operating voltage. This maximizes photon detection efficiency and minimizes gain/efficiency voltage-dependence while eliminating optical cross-talk.
Event anisotropy is expected to have sensitivity to the early stage of ultra-relativistic heavy-ion collisions at RHIC. The possible formation of a quark gluon plasma (QGP) could affect how the ...initial anisotropy in the space coordinate is transfered into the momentum space for the initial state. The anisotropy parameter (v
2) is an amplitude of the 2nd harmonic parameter of the azimuthal distribution with respect to the reaction plane. We present here v
2 of identified and inclusive charged particles measured in the PHENIX central arm detector (∣η∣ < 0.35) with respect to the reaction plane defined at ∣η∣ = 3 ∼ 4 in 200 GeV Au + Au collisions. We find that v
2 increases from central to mid-central collisions reaching a maximum at about 50% of the geometric cross section and then decreases again for more peripheral collisions. As a function of transverse momentum in minimum-bias collisions, the v
2 parameter increases linearly with p
T up to p
T ≅ 2 GeV/c and then saturates for inclusive charged particles. the v
2 parameter of identified particles (π
+, π
−,
K
+,
K
−,
p and
p
¯
follow a hydro-dynamic behavior up to 2 GeV/c in p
T, where the lighter mass particles haver larger v
2 at a given p
T. However there is an indication that this trend is reversed at around p
T ≅ 2GeV/c, where
p and
p
¯
have larger v
2 than π and
K.
Recent results on identified hadrons from the PHENIX experiment in Au+Au collisions at mid-rapidity at
S
N
N
=
200
GeV are presented. The centrality dependence of transverse momentum distributions ...and particle ratios for identified charged hadrons are studied. The transverse flow velocity and freeze-out temperature are extracted from
p
T
spectra within the framework of a hydrodynamic collective flow model. Two-particle HBT correlations for charged pions are measured in different centrality selections for a broad range of transverse momentum of the pair. Results on elliptic flow measurements with respect to the reaction plane for identified particles are also presented.
S. berthaulltii Hawkes, a wild potato species, possesses two types of glandular trichomes on its leaf surface: types A and B wich confer resistance to insects. Preliminary results indicated that the ...presence of glandular trichomes also confers resistance to Phytophthora infestans, the causal agent of late blight. In this paper we report the evaluation of trichome characteristics (density and exudate activities) performed on 8 lines of potato, including the control varieties Desirée and Tropicana, 5 hybrid lines derived from intercrosses and backcrosses between S. tuberosum and S. berthaultii and one accession of S. berthaultii. Whole plants of the 8 genotypes were inoculated with a spore suspension of Phytophthora infestans in order to evaluate their resistance to late blight. The resultant disease incidence correlated negatively with type A trichome density and with polyphenol-oxidase (PPO) activity of type A trichome glands. The removal of type B trichomes exudate by leaf dipping in ethanol did not influence the disease development after artificial inoculation of detached leaves. Type B trichome exudate was extracted and the fraction corresponding to Fatty Acids Sucrose Esters (FASE) was recovered after Thin Layer Chromatography and tested on the fungal mycelium in vitro. The FASE exhibited a slight inhibitory effect on mycelium growth. The results of the experiments are discussed, and several hypotheses regarding the possible role of types A and B trichomes are formulated.PUBLICATION ABSTRACT
Recently, the n\(^3\)He collaboration reported a measurement of the parity-violating (PV) proton directional asymmetry \(A_{\mathrm {PV}} = (1.55\pm 0.97~\mathrm {(st\ at)} \pm 0.24~\mathrm ...{(sys)})\times 10^{-8}\) in the capture reaction of \({}^3\)He\((\vec {n},{\mathrm p}){}^3\)H at meV incident neutron energies. The result increased the limited inventory of precisely measured and calculable PV observables in few-body systems required to further understand the structure of hadronic weak interaction. In this letter, we report the experimental and theoretical investigation of a parity conserving (PC) asymmetry \(A_{\mathrm {PC}}\) in the same reaction (the first ever measured PC observable at meV neutron energies). As a result of S- and P-wave mixing in the reaction, the \(A_{\mathrm {PC}}\) is inversely proportional to the neutron wavelength \(\lambda\). The experimental value is \((\lambda\times A_{\mathrm {PC}})\equiv\beta= (-1.97 \pm 0.28~\mathrm{(stat)}\pm 0.12~\mathrm{(sys)}) \times 10^{-6}\) Amstrongs. We present results for a theoretical analysis of this reaction by solving the four-body scattering problem within the hyperspherical harmonic method. We find that in the \({}^3\)He\((\vec {n},{\mathrm p}){}^3\)H reaction, \(A_{\mathrm {PC}}\) depends critically on the energy and width of the close \(0^-\) resonant state of \({}^4\)He, resulting in a large sensitivity to the spin-orbit components of the nucleon-nucleon force and even to the three-nucleon force. The analysis of the accurately measured \(A_{\mathrm {PC}}\) and \(A_{\mathrm {PV}}\) using the same few-body theoretical models gives essential information needed to interpret the PV asymmetry in the \({}^3\)He\((\vec {n}, {\mathrm p}){}^3\)H reaction.
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