Measurement Of Momentum Research Articles

Orbital angular momentum of Laguerre-Gaussian beams with non-zero radial index at limited aperture size

The study of orbital angular momentum (OAM) calculation and measurement of complex radial structure beams with limited receiving aperture size is of practical significance. In this paper, taking the Laguerre-Gaussian beam with non-zero radial index as an example, we give the calculation method of its OAM at limited aperture size and design an experiment. We theoretically and experimentally demonstrate the strong correlation between OAM and radial number and we believe that the calculation method can be extended to all local OAM calculations with complex radial structure beams.

Price behavior of small-cap stocks and momentum: A study using principal component momentum

This study analyzes why the negative momentum effect appears in Asian (China, Japan, Korea) stock markets, contrary to the U.S. market. We use principal component momentum (PMOM), a newly devised momentum measure. The PMOM is constructed by extracting commonalities from traditional momentum measures using principal component analysis. The results show evidence of positive and negative momentum profits in the U.S. and Asian markets, respectively. Negative momentum profits in Asian markets are attributable to the strong performance reversal of small stocks in the loser portfolio. Conversely, the positive momentum profits of the U.S. market are driven by the performance continuity of small stocks in the winner portfolio. The PMOM strategy is significantly more advantageous than traditional momentum strategies, based on the economic and statistical perspectives of momentum profits. These results are robust to changes in empirical designs.

Number-phase uncertainty relations and bipartite entanglement detection in spin ensembles

We present a method to detect bipartite entanglement based on number-phase-like uncertainty relations in split spin ensembles. First, we derive an uncertainty relation that plays the role of a number-phase uncertainty for spin systems. It is important that the relation is given with well-defined and easily measurable quantities, and that it does not need assuming infinite dimensional systems. Based on this uncertainty relation, we show how to detect bipartite entanglement in an unpolarized Dicke state of many spin-1/2 particles. The particles are split into two subensembles, then collective angular momentum measurements are carried out locally on the two parts. First, we present a bipartite Einstein-Podolsky-Rosen (EPR) steering criterion. Then, we present an entanglement condition that can detect bipartite entanglement in such systems. We demonstrate the utility of the criteria by applying them to a recent experiment given in K. Lange et al. [Science 360, 416 (2018)] realizing a Dicke state in a Bose-Einstein condensate of cold atoms, in which the two subensembles were spatially separated from each other. Our methods also work well if split spin-squeezed states are considered. We show in a comprehensive way how to handle experimental imperfections, such as the nonzero particle number variance including the partition noise, and the fact that, while ideally BECs occupy a single spatial mode, in practice the population of other spatial modes cannot be fully suppressed.

Structural and dynamical studies of CH–π bonded CH4–C6H6 dimer by ultrafast intermolecular Coulombic decay

The inner-valence ionization and fragmentation dynamics of CH4–C6H6 dimer induced by 200 eV electron impact is studied utilizing a multi-particle coincidence momentum spectroscopy. The three-dimensional momentum vectors and kinetic energy release (KER) of the CH4 ++C6H6 + ion pairs are obtained by coincident momentum measurement. Our analysis on the absolute cross sections indicates that the intermediate dication CH4 +–C6H6 + is preferentially produced by the removal of an inner-valence electron from CH4 or C6H6 and subsequent relaxation of ultrafast intermolecular Coulombic decay followed by two-body Coulomb explosion. Combining with ab initio molecular dynamics (AIMD) simulations, the real-time fragmentation dynamics including translational, vibrational and rotational motions are presented as a function of propagation time. The revealed fragmentation dynamics are expected to have a potential implication for crystal structure imaging with various radiation sources.

Continuous simultaneous measurement of position and momentum of a particle

We formulate a model of a quantum particle continuously monitored by detectors measuring simultaneously its position and momentum. We implement the postulate of wave-function collapse by assuming that upon detection the particle is found in one of the meters' states chosen as a discrete subset of coherent states. The dynamics, as observed by the meters, is thus a random sequence of jumps between coherent states. We generate such trajectories using the quantum Monte Carlo wave-function method. For sparsely distributed detectors, we use methods from renewal theory of stochastic processes to obtain some semianalytic results. In particular, the different regimes of dynamics of the free particle are identified and quantitatively discussed: from stroboscopic motion in the case of low interrogation frequency, to delayed dynamics reminiscent of the Zeno effect if monitoring is frequent. For a semicontinuous spatial distribution of meters the emergence of classical trajectories is shown. Their statistical properties are discussed and compared to other detection schemes in which the operation on the system due to measurement corresponds to ``spatial filtering'' of the wave function.

Corrections for regular identification of high energy positive particles in experimental data using lobachevsky space

In this work, high-energy positive charged particles are distinguished using the Lobachevsky space or Hyperbolic space, which is defined as the total rapidity multiplied by hyperbolic cosines of the transverse and longitudinal rapidity of the particles. Experimental data from eight different types of interactions detected in the bubble chambers accumulated in the high-energy sector were used in the calculations. The weights used to construct the proton and positive pion distributions for each of the interacting secondary particles have been eliminated, allowing such studies to be performed such as particle counting and clustering.These weights do not include calculated weights at azimuth angles, near the center of the star, or without momentum measurements. We now have the opportunity to study positive pions and protons. The percentage of confused particles increases with the beam energy.
 After the reconstruction, we conducted a study of the temperature of the charged particles produced by the p + p interaction of 205 GeV, where Tsallis temperatures are close to Hagedorn . On the other hand, Hagedor and temperatures are higher than Tsallis, which means that the unstable states exchange heat as they move to equilibrium.

A plano-convex thick-lens velocity map imaging apparatus for direct, high resolution 3D momentum measurements of photoelectrons with ion time-of-flight coincidence.

Since their inception, velocity map imaging (VMI) techniques have received continued interest in their expansion from 2D to 3D momentum measurements through either reconstructive or direct methods. Recently, much work has been devoted to the latter of these by relating electron time-of-flight (TOF) to the third momentum component. The challenge is having a timing resolution sufficient to resolve the structure in the narrow (<10ns) electron TOF spread. Here, we build upon the work in VMI lens design and 3D VMI measurement by using a plano-convex thick-lens (PCTL) VMI in conjunction with an event-driven camera (TPX3CAM) providing TOF information for high resolution 3D electron momentum measurements. We perform simulations to show that, with the addition of a mesh electrode to the thick-lens geometry, the resulting plano-convex electrostatic field extends the detectable electron cutoff energy range while retaining the high resolution. This design also extends the electron TOF range, allowing for a better momentum resolution along this axis. We experimentally demonstrate these capabilities by examining above-threshold ionization in xenon, where the apparatus is shown to collect electrons of energy up to ∼7eV with a TOF spread of ∼30ns, both of which are improved compared to a previous work by factors of ∼1.4 and ∼3.75, respectively. Finally, the PCTL-VMI is equipped with a coincident ion TOF spectrometer, which is shown to effectively extract unique 3D momentum distributions for different ionic species in a gas mixture. These techniques have the potential to lend themselves to more advanced measurements involving systems where the electron momentum distributions possess non-trivial symmetries.

Particle identification with the cluster counting technique for the IDEA drift chamber

IDEA (Innovative Detector for an Electron–positron Accelerator) is a general-purpose detector concept, designed to study electron–positron collisions in a wide energy range in a very large circular leptonic collider. Its drift chamber is designed to provide an efficient tracking, a high precision momentum measurement and an excellent particle identification by exploiting the application of the cluster counting technique. To investigate the potential of the cluster counting techniques on physics events, a simulation of the ionization cluster generation is needed, therefore we developed an algorithm which can use the energy deposit information provided by the Geant4 toolkit to reproduce, in a fast and convenient way, the cluster number and cluster size distributions. The results obtained confirm that the cluster counting technique allows to reach a resolution two times better than the traditional dE/dx method. A beam test has been performed during November 2021 at CERN on the H8 beam line to validate the simulations results, to define the limiting effects for a fully efficient cluster counting and to count the number of electron clusters released by an ionizing track at a fixed βγ as a function of the track angle. The simulation and the beam test results will be described briefly in this issue.

On Majorization Uncertainty Relations in the Presence of a Minimal Length

The emergence of a minimal length at the Planck scale is consistent with modern developments in quantum gravity. This is taken into account by transforming the Heisenberg uncertainty principle into the generalized uncertainty principle. Here, the position-momentum commutator is modified accordingly. In this paper, majorization uncertainty relations within the generalized uncertainty principle are considered. Dealing with observables with continuous spectra, each of the axes of interest is divided into a set of non-intersecting bins. Such formulation is consistent with real experiments with a necessarily limited precision. On the other hand, the majorization approach is mainly indicative for high-resolution measurements with sufficiently small bins. Indeed, the effects of the uncertainty principle are brightly manifested just in this case. The current study aims to reveal how the generalized uncertainty principle affects the leading terms of the majorization bound for position and momentum measurements. Interrelations with entropic formulations of this principle are briefly discussed.

Role of bulk viscosity in deuteron production in ultrarelativistic nuclear collisions

We use a Bayesian-calibrated multistage viscous hydrodynamic model to explore deuteron yield, mean transverse momentum and flow observables in Pb-Pb collisions at the Large Hadron Collider. We explore theoretical uncertainty in the production of deuterons, including (i) the contribution of thermal deuterons, (ii) models for the subsequent formation of deuterons (hadronic transport vs coalescence), and (iii) the overall sensitivity of the results to the hydrodynamic model, in particular to bulk viscosity, which is often neglected in studies of deuteron production. Using physical parameters set by a comparison to only light hadron observables, we find good agreement with measurements of the mean transverse momentum 〈pT〉 and elliptic flow v2 of deuterons; however, tension is observed with experimental data for the deuteron multiplicity in central collisions. The results are found to be sensitive to each of the mentioned theoretical uncertainties, with a particular sensitivity to bulk viscosity, indicating that the latter is an important ingredient for an accurate treatment of deuteron production.1 MoreReceived 26 March 2022Accepted 7 October 2022DOI:https://doi.org/10.1103/PhysRevC.106.064901Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCollective flowParticle & resonance productionParticle correlations & fluctuationsQuark-gluon plasmaRelativistic heavy-ion collisionsThermal & statistical modelsTechniquesBayesian methodsNuclear PhysicsParticles & Fields

Restrictions Imposed by the Wave Function on the Results of Particle Momentum Measurements

Using the example of the quantum dynamics of a particle in a one-dimensional configuration space (OCS), it is shown that to know the wave function implies not only statistical restrictions on the measurement results: the integrand in the standard formula for calculating the average values of (self-adjoint) operators and the Schr\"{o}dinger equation for the modulus and phase of the wave function uniquely also define ' fields of operators' as functions of coordinate and time. A key role in establishing the physical meaning of these fields is played by the fact that the field of the kinetic energy operator contains two heterogeneous contributions: the first is determined by the field of the momentum operator, which is related only to the phase of the wave function, and the second coincides with the so-called "quantum mechanical potential", which is related only to the amplitude of the wave function. The values of these fields at each point of the OCS are considered as the average values of the corresponding observables for a pair of noninteracting particles (for a pair of systems of a one-particle ensemble). At each such point, the first contribution to the field of kinetic energy describes the kinetic energy of the center of mass of a pair of particles, and the second -- the energy of their motion relative to the center of mass. The field of the momentum operator and the field of the kinetic energy operator, taking into account the K\"{o}nig theorem, uniquely determine in the OCS two fields of particle momentum values at each point of the OCS. An analogue of the Heisenberg inequality for the deviations of both momentum fields from the field of the momentum operator is obtained.

Encapsulated resistive anode bulk Micromegas detectors for the T2K experiment TPC upgrade

In order to establish accurate leptonic CP violation at 3 σ level for a significant fraction of the possible δCP values, the T2K collaboration plan to upgrade the beam intensity and to upgrade the near detector ND280.The T2K experiment consists of a totally active Super-Fine-Grained-Detector, two High Angle Time Projection Chamber and six time of flight planes. The HA-TPC will be used for 3D track reconstruction, momentum measurement and particle identification. These time projection chambers, with overall dimensions of 2 × 2 × 0.8 m3, will be equipped with 32 encapsulated resistive anode bulk Micromegas detectors. The thin field cage (3 cm thickness, 4% radiation length) will consist of composite material with a Kapton foil with copper strips as inner layer. The 42 × 34 cm2 ERAM detector will use a 400 kΩ/sq diamond-like carbon foil to spread the charge over the pad plane, each pad being approximately 1 cm2. New front-end electronic cards, based on the AFTER chip, directly mounted on the back of the detector and parallel to its plane have been developed and used for the signal readout.The first production ERAM detector modules have been tested in a lab using a X-ray bench and a cosmic bench. In July 2021, data have also been taken in a test beam at DESY in 0.2 T magnetic field. Performance characterization and results from these measurement campaigns will be shown.

Eigenmodes of aberrated systems: the tilted lens

When light propagates through aberrated optical systems, the resulting degradation in amplitude and phase has deleterious effects, for example, on resolution in imaging, spot sizes in focussing, and the beam quality factor of the output beam. Traditionally, this is either pre- or post-corrected by adaptive optics or phase conjugation. Here, we consider the medium as a complex channel and determine the corresponding eigenmodes which are impervious of the channel perturbation. We employ a quantum-inspired approach and apply it to the tilted lens as our example channel, a highly astigmatic system that is routinely used as a measure of orbital angular momentum. We find the eigenmodes analytically, show their robustness in a practical experiment, and outline how this approach may be extended to arbitrary astigmatic systems.

Measurements of the angular momentum–mass relations in the Simba simulation

We present measurements of the specific angular momentum content (j) of galaxies drawn from the Simba cosmological hydrodynamic simulations. For the stellar, Hi and baryonic matter components we demonstrate the existence of extremely tight relations between j and the mass contained within the radius at which the Hi mass surface density decreases to 1 M⊙ pc−2. These relations are broadly consistent with a variety of empirical measurements. We confirm the observational result that the scatter in the stellar j–M relation is driven largely by Hi content, and measure the dependence of its scatter on the deviations of galaxies from other important scaling relations. For a given stellar mass, Hi-rich/poor galaxies have more/less-than-average stellar specific angular momentum. A similar, yet weaker, correlation exists for Hi mass fraction. Overall, our results demonstrate the utility of the Simba simulations as a platform for understanding and contextualising the data and results from forthcoming large galaxy surveys.

The HIBEAM/NNBAR Calorimeter Prototype

The HIBEAM/NNBAR experiment is a free-neutron search for n → sterile n and n → oscillations planned to be installed at the European Spallation Source under construction in Lund, Sweden. A key component in the experiment is the detector to identify n – annihilation events, which will produce on average four pions with a final state invariant mass of two nucleons, around 1.9 GeV. The beamline and experiment are shielded from magnetic fields which would suppress n → transitions, thus no momentum measurement will be possible. Additionally, calorimetry for particles with kinetic energies below 600 MeV is challenging, as traditional sampling calorimeters used in HEP would suffer from poor shower statistics. A design study is underway to use a novel approach of a hadronic range measurement in multiple plastic scintillator layers, followed by EM calorimetery with lead glass. A prototype calorimeter system is being built, and will eventually be installed at an ESS test beam line for in situ neutron background studies.

Advances in Cosmic Ray Muon Computed Tomography and Fieldable Spectroscopy

A recent example of successful technology transition from high energy physics to practical engineering applications is cosmic ray muon tomography. Cosmic ray muon tomography, is a promising non-destructive technique that has been recently utilized to monitor or image the contents of dense or well shielded objects, typically not feasible with conventional radiography techniques, e.g., x-ray or neutron. Cosmic ray muon tomography has been used with various levels of success in spent nuclear fuel monitoring, volcano imaging, and cargo container imaging. Further, knowledge of cosmic ray muon momentum spectrum has the potential to significantly improve and expand the use of a variety of recently developed muon-based radiographic techniques. However, existing muon tomography systems rely only on muon tracking and have no momentum measurement capabilities which reduces the image resolution and requires longer measurement times. A fieldable cosmic ray muon spectrometer with momentum measurement capabilities for use in muon tomography is currently missing. In this paper, we will discuss and explore recent advances in cosmic ray muon computed tomography and spectroscopy and their applications to engineering including a new concept for measuring muon momentum using multiple gaseous Cherenkov radiators. By varying the pressure of multiple gas Cherenkov radiators, a set of muon momentum threshold levels can be selected that are triggered only when the incoming muon momentum exceeds that level. As a result, depending on the incoming muon momentum, none to all Cherenkov radiators can be triggered. By analyzing the signals from each radiator, we can estimate the actual muon momentum.

On‐Chip Plasmonic Vortex Interferometers (Laser Photonics Rev. 16(10)/2022)

Optical Interferometers In article number 2200242, Yuan-Hao Lang, Quan Xu, and colleagues have developed a new form of optical interferometers by customizing the plasmonic vortex generation from two spin channels. In several square wavelengths, plasmonic vortex interferometer constructs interference field with subwavelength fine structure, demonstrating the measurement of polarization state, spin, and orbital angular momentum of the incident light beam.

Experimental investigation for pulsed laser nitriding of metals

Pulsed laser nitriding of active metals has been regarded as a promising method for performance enhancement of metals. Nevertheless, clarifying the complicated mechanisms of pulsed laser nitriding such as the nitrogen transport and the chemically active state of nitrogen poses challenges due to the rather fast and complex processes. In this work, the in situ momentum measurements, in situ laser-induced breakdown spectroscopy (LIBS) measurements, in situ transient off-axis Digital holography (TODH) measurements and energy dispersive spectroscopy measurements were implemented to investigate the pulsed laser nitriding. It was revealed experimentally that the laser-supported-detonation (LSD) may be the key, and the nitriding process could proceed effectively only when the illumination power density of laser can reach the threshold of generating LSD. The LSD-induced high-speed N+ ions and N atoms flow to the metal surface, which may be the major mechanism for the nitrogen transporting to the metal surface. Moreover, the experimental results of LIBS showed that the chemically active state of nitrogen is N+ ions and their lifetime is at the scale of 102 ns. The lifetime of N+ ions was found to be prolonged as the nitrogen pressure was increased. As indicated by TODH experimental results, the prolonged lifetime of N+ ions may be caused by the smaller shock wave velocity at the higher nitrogen pressure. These experimental findings in this work may clarify the nitrogen transport mechanism and the chemically active state of nitrogen, which may lead to a better understanding of the pulsed laser nitriding and provide the guidance for optimizing the related industrial design in the future.

Exploring the SMEFT at dimension eight with Drell-Yan transverse momentum measurements

Effective field theories (EFTs) are used to parameterize searches for new physics in a largely model-independent way. Here, the authors study Drell-Yan processes at the LHC including terms up to dimension 8 in the EFT expansion. They find that these higher-dimension operators can be probed in the future and are potentially important in distinguishing different models.

Angle and angular momentum: Uncertainty relations, simultaneous measurement, and phase-space representation

Reaching ultimate performance of quantum technologies requires the use of detection at quantum limits and access to all resources of the underlying physical system. We establish a full quantum analogy between the pair of angular momentum and exponential angular variable, and the structure of canonically conjugate position and momentum. This includes the notion of optimal simultaneous measurement of the angular momentum and angular variable, the identification of Einstein-Podolsky-Rosen-like variables and states, and, finally, a phase-space representation of quantum states. Our construction is based on close interconnection of the three concepts and may serve as a template for the treatment of other observables. This theory also provides a test bed for implementation of quantum technologies combining discrete and continuous quantum variables.