Violation Experiment Research Articles

Attention to inattention: effect of the other's attentional state on visual search performance in chimpanzees.

In the present study, we examined the effects of the other's triadic attention to objects on visual search performances in chimpanzees. We found the search-asymmetry-like effect of the other's attentional state; the chimpanzees searched a target object not attended by the other individual more efficiently than that attended (Experiment 1). Additional experiments explored the possibility that the other individual "holding an object but not looking at it" led to expectancy violation (Experiment 2) or the role of nonsocial cues such as the proximity relation between the head and the object (Experiment 3). Still, these accounts alone did not explain this effect. It was also shown that the other's attentional state affected the chimpanzees' performances more readily as the interference effect than the facilitation effect (Experiment 4). Furthermore, the same effect was observed in the visual search for the gaze (head direction) of others (Experiment 5). We obtained the same results using photographs of chimpanzees (Experiment 6). Contrary to the chimpanzees, humans detected the object to which attention was directed more efficiently than vice versa (Experiment 7). The present results may reflect species differences between chimpanzees and humans in processing triadic social attention.

Redesigning the Jefferson Lab Hall A beam line for high precision parity experiments

The Continuous Electron Beam Accelerator Facility (CEBAF) was built with a thermionic electron source and the three original experimental hall lines reflected this. A few years after beam delivery began a parity violation experiment was approved and two polarimeters were installed in the Hall A beam line. The beam raster system was placed after the new Compton polarimeter, before one accelerator quadrupole and four quadrupoles in the new Moller polarimeter. It was very difficult to meet experimental requirements on envelope functions and raster shape with this arrangement so a sixth quadrupole was installed downstream of the Moller polarimeter to provide an additional degree of freedome. All of the parity experiments in Hall A have been run with this still-unsatisfactory configuration. The MOLLER experiment is predicated on achieving a 2% error on a 32 ppb asymmetry. Beam line changes are required to meet the systematic error budget. This paper documents the existing beam line, an interim change which can be accomplished during a annual maintenance down, and the final configuration for MOLLER and subsequent experiments.

The muX project

The project is conducting a series of muonic X-ray measurements in medium- and high-Z nuclei at PSI, utilizing a high-purity germanium detector array, in-beam muon detectors, and a modern digital data-acquisition system. A novel hydrogen target for muon transfer was developed, enabling measurements with as little as a few micrograms of target material. First measurements with radioactive Cm and Ra targets were conducted, aimed at determining their nuclear charge radii. These serve as important input for upcoming atomic parity violation experiments. The apparatus is also used to perform a feasibility study of an atomic parity violation experiment with the 2s-1s2s−1s muonic X-ray transition. In addition, the setup has been made available for a wider range of nuclear, particle, and solid-state physics measurements.

Muon and electron g−2 and proton and cesium weak charges implications on dark Zd models

Theories beyond the standard model involving a sub-GeV-scale vector ${Z}_{d}$ mediator have been largely studied as a possible explanation of the experimental values of the muon and electron anomalous magnetic moments. Motivated by the recent determination of the anomalous muon magnetic moment performed at Fermilab, we derive the constraints on such a model obtained from the magnetic moment determinations and the measurements of the proton and cesium weak charge, ${Q}_{W}$, performed at low-energy transfer. In order to do so, we revisit the determination of the cesium ${Q}_{W}$ from the atomic parity violation experiment, which depends critically on the value of the average neutron rms radius of $^{133}\mathrm{Cs}$, by determining the latter from a practically model-independent extrapolation from the recent average neutron rms radius of $^{208}\mathrm{Pb}$ performed by the PREX-2 Collaboration. From a combined fit of all the aforementioned experimental results, we obtain rather precise limits on the mass and the kinetic mixing parameter of the ${Z}_{d}$ boson, namely ${m}_{{Z}_{d}}={47}_{\ensuremath{-}16}^{+61}\text{ }\text{ }\mathrm{MeV}$ and $ϵ={2.3}_{\ensuremath{-}0.4}^{+1.1}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, when marginalizing over the $Z\ensuremath{-}{Z}_{d}$ mass mixing parameter $\ensuremath{\delta}$.

Laser-based measurement of parity violation in hydrogen

A parity violation experiment based on stimulated emission in atomic hydrogen is analyzed. The intensity of a laser field within an optical cavity provides the experimental signal. We find that such a measurement would offer several advantages compared to previous experiments based on microwave spectroscopy, including a well-defined interaction region and a short coherent interaction time.

“Mind full or mindful” – can mere cognitive busyness lead to compliance similar to an emotional seesaw?

ABSTRACTThe emotional seesaw phenomenon (ESP) is a social-influence technique in which a person experiences a certain emotion, where the external stimulus that evoked the emotion suddenly disappears. Large effects on compliance and impaired cognitive functioning were reported after ESPs. The present research (total N = 163) tests a generalization of this phenomenon: whether mere cognitive busyness leads to similar effects by provoking an inner focus. Two experiments closely modeled after previous ESP experiments supported this reasoning: a simple expectancy violation (Experiment 1) and cognitive load (Experiment 2) caused a comparable pattern of results as the ESP. Experiment 3 demonstrated that also the ESP fostered an inner focus and consequently compliant behavior. We discuss mechanisms underlying social-influence techniques.

A new experimental method to search for T-violation using a sequential CeF3 scintillating calorimeter

Abstract A new experimental method to search for T -violating transverse muon polarization ( P T ) in the K + → π 0 μ + ν ( K μ 3 ) decay is proposed. In this new experiment, the measurements of the μ + momentum vector, the π 0 momentum vector, and the μ + polarization will be performed by the same electro-magnetic calorimeter. One of key issues is the choice of a scintillation material which can preserve the μ + spin polarization for several μ + lifetimes. A test experiment to measure the residual μ + polarization in a Ce F 3 scintillating crystal was performed at J-PARC Material and Life Science Facility (MLF). We concluded that the residual μ + polarization in Ce F 3 is high enough to perform the new T -violation experiment.

Finding the P3 in the P600: Decoding shared neural mechanisms of responses to syntactic violations and oddball targets

The P600 Event-Related Brain Potential, elicited by syntactic violations in sentences, is generally interpreted as indicating language-specific structural/combinatorial processing, with far-reaching implications for models of language. P600 effects are also often taken as evidence for language-like grammars in non-linguistic domains like music or arithmetic. An alternative account, however, interprets the P600 as a P3, a domain-general brain response to salience. Using time-generalized multivariate pattern analysis, we demonstrate that P3 EEG patterns, elicited in a visual Oddball experiment, account for the P600 effect elicited in a syntactic violation experiment: P3 pattern-trained MVPA can classify P600 trials just as well as P600-trained ones. A second study replicates and generalizes this finding, and demonstrates its specificity by comparing it to face- and semantic mismatch-associated EEG responses. These results indicate that P3 and P600 share neural patterns to a substantial degree, calling into question the interpretation of P600 as a language-specific brain response and instead strengthening its association with the P3. More generally, our data indicate that observing P600-like brain responses provides no direct evidence for the presence of language-like grammars, in language or elsewhere.

Design and performance of a lead fluoride detector as a luminosity monitor

Precise luminosity measurements for the OLYMPUS two-photon exchange experiment at DESY were performed by counting scattering events with alternating beams of electrons and positrons incident on atomic electrons in a gaseous hydrogen target. Final products of Møller, Bhabha, and pair annihilation interactions were observed using a pair of lead fluoride Cherenkov calorimeters with custom housings and electronics, adapted from a system used by the A4 parity violation experiment at MAMI. This paper describes the design, calibration, and operation of these detectors. An explanation of the Monte Carlo methods used to simulate the physical processes involved both at the scattering vertices and in the detector apparatus is also included.

Spin Physics at J-PARC

Spin-physics projects at J-PARC are explained by including future possibilities. J-PARC is the most-intense hadron-beam facility in the high-energy region above multi-GeV, and spin physics will be investigated by using secondary beams of kaons, pions, neutrinos, muons, and antiproton as well as the primary-beam proton. In particle physics, spin topics are on muon [Formula: see text], muon and neutron electric dipole moments, and time-reversal violation experiment in a kaon decay. Here, we focus more on hadron-spin physics as for future projects. For example, generalized parton distributions (GPDs) could be investigated by using pion and proton beams, whereas they are studied by the virtual Compton scattering at lepton facilities. The GPDs are key quantities for determining the three-dimensional picture of hadrons and for finding the origin of the nucleon spin including partonic orbital-angular-momentum contributions. In addition, polarized parton distributions and various hadron spin topics should be possible by using the high-momentum beamline. The strangeness contribution to the nucleon spin could be also investigated in principle with the neutrino beam with a near detector facility.

Determination of the $3\gamma $ Fraction from Positron Annihilation in Mesoporous Materials for Symmetry Violation Experiment with J-PET Scanner

Various mesoporous materials were investigated to choose the best material for experiments requiring high yield of long-lived positronium. We found that the fraction of 3\gamma annihilation determined using \gamma-ray energy spectra and positron annihilation lifetime spectra (PAL) changed from 20% to 25%. The 3gamma fraction and o-Ps formation probability in the polymer XAD-4 is found to be the largest. Elemental analysis performed using scanning electron microscop (SEM) equipped with energy-dispersive X-ray spectroscop EDS show high purity of the investigated materials.

Bell violation using entangled photons without the fair-sampling assumption

The violation of a Bell inequality is an experimental observation that forces the abandonment of a local realistic viewpoint--namely, one in which physical properties are (probabilistically) defined before and independently of measurement, and in which no physical influence can propagate faster than the speed of light. All such experimental violations require additional assumptions depending on their specific construction, making them vulnerable to so-called loopholes. Here we use entangled photons to violate a Bell inequality while closing the fair-sampling loophole, that is, without assuming that the sample of measured photons accurately represents the entire ensemble. To do this, we use the Eberhard form of Bell's inequality, which is not vulnerable to the fair-sampling assumption and which allows a lower collection efficiency than other forms. Technical improvements of the photon source and high-efficiency transition-edge sensors were crucial for achieving a sufficiently high collection efficiency. Our experiment makes the photon the first physical system for which each of the main loopholes has been closed, albeit in different experiments.

Selection Tests of MnZn and NiZn Ferrites for Mu2e 300 kHz and 5.1 MHz AC Dipoles

Mu2e, a charged lepton flavor violation (CLFV) experiment is planned to start at Fermilab late in this decade. The proposed experiment will search for neutrinoless muon to electron conversions with unprecedented sensitivity, better than at 90% CL. To achieve this sensitivity the incoming proton beam must be highly suppressed during the window for detecting the muon decays. The current proposal for beam extinction is based on a collimator design with two dipoles running at 300 kHz and 5.1 MHz and synchronized to the proton bunch spacing. The appropriate choice of ferrite material for the magnet yoke is a critical step in the overall design of the dipoles and their reliable operation at such high frequencies over the life of the experiment. This choice, based on a series of the thermal and magnetic measurements of the ferrite samples, is discussed in the paper. Additionally, the first results from the testing at 300 kHz of a prototype AC dipole are presented.

A4 Compton polarimetry

For the A4 parity violation experiment at MAMI we have installed a Compton laser polarimeter in our beam line. We have now operated this polarimeter at different beam energies of 315, 855, and 1508 MeV. A short overview of our detectors for scattered photons and electrons is given, together with a discussion of the extraction of Compton asymmetries using tagged photon spectra.

Real-time calibration of the A4 electromagnetic lead fluoride (PbF 2) calorimeter

Sufficient energy resolution is the key issue for the calorimetry in particle and nuclear physics. The calorimeter of the A4 parity violation experiment at MAMI is a segmented calorimeter where the energy of an event is determined by summing the signals of neighboring channels. In this case, the precise matching of the individual modules is crucial to obtain a good energy resolution. We have developed a calibration procedure for our total absorbing electromagnetic calorimeter which consists of 1022 lead fluoride (PbF 2) crystals. This procedure reconstructs the single-module contributions to the events by solving a linear system of equations, involving the inversion of a 1022×1022-matrix. The system has shown its functionality at beam energies between 300 and 1500 MeV and represents a new and fast method to keep the calorimeter permanently in a well-calibrated state.

High resolution spectroscopy of methyltrioxorhenium: towards the observation of parity violation in chiral molecules

Originating from the weak interaction, parity violation in chiral molecules has been considered as a possible origin of the biohomochirality. It was predicted in 1974 but has never been observed so far. Parity violation should lead to a very tiny frequency difference in the rovibrational spectra of the enantiomers of a chiral molecule. We have proposed to observe this predicted frequency difference using the two photon Ramsey fringes technique on a supersonic beam. Promising candidates for this experiment are chiral oxorhenium complexes, which present a large effect, can be synthesized in large quantity and enantiopure form, and can be seeded in a molecular beam. As a first step towards our objective, a detailed spectroscopic study of methyltrioxorhenium (MTO) has been undertaken. It is an ideal test molecule as the achiral parent molecule of chiral candidates for the parity violation experiment. For the 187Re MTO isotopologue, a combined analysis of Fourier transform microwave and infrared spectra as well as ultra-high resolution CO2 laser absorption spectra enabled the assignment of 28 rotational lines and 71 rovibrational lines, some of them with a resolved hyperfine structure. A set of spectroscopic parameters in the ground and first excited state, including hyperfine structure constants, was obtained for the antisymmetric Re=O stretching mode of this molecule. This result validates the experimental approach to be followed once a chiral derivative of MTO will be synthesized, and shows the benefit of the combination of several spectroscopic techniques in different spectral regions, with different set-ups and resolutions. First high resolution spectra of jet-cooled MTO, obtained on the set-up being developed for the observation of molecular parity violation, are shown, which constitutes a major step towards the targeted objective.

Laser spectroscopy of trapped short-lived Ra+ions

As an important step toward an atomic parity violation experiment in one single trapped Ra${}^{+}$ ion, laser spectroscopy on short-lived $^{212,213,214}\mathrm{Ra}$${}^{+}$ ions was conducted. The isotope shift of the $6 {}^{2}{D}_{3/2}$-$7 {}^{2}{P}_{1/2} $and $6 {}^{2}{D}_{3/2}$-$7 {}^{2}{P}_{3/2} $transitions and the hyperfine structure constants of the $7 {}^{2}{P}_{1/2} $and $6 {}^{2}{D}_{3/2} $states in $^{213}\mathrm{Ra}$${}^{+}$ were measured, which provides a benchmark for the required atomic theory. A lower limit of $232(4)$ ms for $6 {}^{2}{D}_{5/2} $state lifetime was determined.

Measurement of the Magnetic and Thermal Characteristics of Ferrites for a 300 kHz AC Dipole for the Mu2e Experiment

A charged lepton flavor violation experiment, Mu2e, is planned at Fermilab, searching for muon to electron conversions with an unprecedented sensitivity, better than 6 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-17</sup> at 90% CL. To achieve such sensitivity the incoming beam must be highly suppressed during the window for detecting the conversion a muon into an electron. One proposal for beam extinction is based on a collimator with two dipoles running in a resonant circuit at ~300 kHz synchronized to the bunch spacing. An appropriate choice of the ferrite material for the magnet yoke is critical to ensuring the reliable operation of such a high frequency dipole over the life of the experiment. In this paper, we present the results of the thermal and magnetic measurements of the selected ferrite material, including the field non-linearity effects and power losses. Some dimensional optimization of the ferrite bricks is also discussed.

A Future High Statistics Charm Mixing Experiment Using the Fermilab Tevatron

We present an idea for a future D0-D0bar mixing and CP violation experiment to run at the Fermilab Tevatron. We estimate that in three years of running, such an experiment could reconstruct an order of magnitude more flavor-tagged D0->K+pi- decays than will be reconstructed by the B-factory experiments with their full data sets. The resulting sensitivity to CP-violating parameters |q/p| and Arg(q/p) is calculated from a global fit to CP-violating observables, and it is found to be much greater than current world sensitivity.

Measurement of light shifts at two off-resonant wavelengths in a single trappedBa+ion and the determination of atomic dipole matrix elements

We have measured the ratio $R$ of the vector ac Stark effect (or light shift) in the $6{S}_{1∕2}$ and $5{D}_{3∕2}$ states of a single trapped barium ion to 0.2% accuracy at two different off-resonant wavelengths. We earlier found $R={\ensuremath{\Delta}}_{S}∕{\ensuremath{\Delta}}_{D}=\ensuremath{-}11.494(13)$ at $514.531\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ where ${\ensuremath{\Delta}}_{S,D}$ are the vector light shifts of the $6{S}_{1∕2}$ and $5{D}_{3∕2}$ $m=\ifmmode\pm\else\textpm\fi{}1∕2$ splittings due to circularly polarized light, and now we report the value at $1111.68\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$, $R=+0.4176(8)$. These observations together yield a value of the $⟨5D\ensuremath{\Vert}er\ensuremath{\Vert}4F⟩$ matrix element. Also, comparison of our results with an ab initio calculation of dynamic polarizability would yield a test of atomic theory and improve the understanding of atomic structure needed to interpret a proposed atomic parity violation experiment.