Towards the production of an ultra cold antihydrogen beam with the AEGIS apparatus

The AEGIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) experiment is an international collaboration, based at CERN, with the experimental goal of performing the first direct measurement of the Earth’s gravitational acceleration on antihydrogen. In the first phase of the experiment, a gravity measurement with 1% precision will be performed by passing a beam of ultra cold antihydrogen atoms through a classical Moiré deflectometer coupled to a position sensitive detector. The key requirements for this measurement are the production of ultra cold (T～100?mK) Rydberg state antihydrogen and the subsequent Stark acceleration of these atoms. The aim is to produce Rydberg state antihydrogen by means of the charge exchange reaction between ultra cold antiprotons (T～100?mK) and Rydberg state positronium. This paper will present details of the developments necessary for the successful production of the ultra cold antihydrogen beam, with emphasis on the detector that is required for the development of these techniques. Issues covered will include the detection of antihydrogen production and temperature, as well as detection of the effects of Stark acceleration.     

Cold and stable antimatter for fundamental physics

The field of cold antimatter physics has rapidly developed in the last 20 years, overlapping with the period of the Antiproton Decelerator (AD) at CERN. The central subjects are CPT symmetry tests and Weak Equivalence Principle (WEP) tests. Various groundbreaking techniques have been developed and are still in progress such as to cool antiprotons and positrons down to extremely low temperature, to manipulate antihydrogen atoms, to construct extremely high-precision Penning traps, etc. The precisions of the antiproton and proton magnetic moments have improved by six orders of magnitude, and also laser spectroscopy of antihydrogen has been realized and reached a relative precision of 2 × 10⁻¹² during the AD time. Antiprotonic helium laser spectroscopy, which started during the Low Energy Antiproton Ring (LEAR) time, has reached a relative precision of 8 × 10⁻¹⁰. Three collaborations joined the WEP tests inventing various unique approaches. An additional new post-decelerator, Extra Low ENergy Antiproton ring (ELENA), has been constructed and will be ready in 2021, which will provide 10–100 times more cold antiprotons to each experiment. A new era of the cold antimatter physics will emerge soon including the transport of antiprotons to other facilities.     

Equivalence principles and gauge fields

We investigate the implication of the week equivalence principles and Eötvös-Dicke experiments for gauge fields in a general framework. In particular, we show that the Galileo weak equivalence principle (WEP[I]) implies the Einstein equivalence principle (EEP) with one exception; however, the second weak equivalence statement (WEP[II]) implies EEP. For the exceptional case, there are anomalous torques on polarized test bodies. As an example, we apply our results to quantum chromodynamics.     

Quantum phenomena in gravitational field

The subjects presented here are very different. Their common feature is that they all involve quantum phenomena in a gravitational field: gravitational quantum states of ultracold antihydrogen above a material surface and measuring a gravitational interaction of antihydrogen in AEGIS, a quantum trampoline for ultracold atoms, and a hypothesis on naturally occurring gravitational quantum states, an Eötvös-type experiment with cold neutrons and others. Considering them together, however, we could learn that they have many common points both in physics and in methodology.     

Verification of the weak equivalence principle with Laue diffracting neutrons: Test experiment

We propose a novel experiment to test the weak equivalence principle (WEP) for the Laue diffracting neutron. Our experiment is based on an essential magnification of an external affect on neutron diffracting by Laue for the Bragg angles close to the right one in couple with additional enhancement factor which exists due to the delay of the Laue diffracting neutron at such Bragg angles. This enhancement phenomena is proposed to be utilized for measuring the force which deviates from zero if WEP is violated. The accuracy of measuring inertial to gravitational neutron masses ratio for the introduced setup can reach ～10^?5, which is more than one order superior to the best present-day result.     

Effect of gravity gradient in weak equivalence principle test

A high accuracy test of the weak equivalence principle(WEP) is of great scientific significance no matter whether its result is positive. We analyze the gravity gradient effect which is a main systematic error source in the test of WEP.The result shows that the uncompensated gravity gradient effect from the coupling term of the dominated gravity gradient multipole moment component q_(21) and the relative multipole field component Q_(21) contributes to an uncertainty of 1×10~(-11) on the E¨otv¨os parameter. We make a Q_(21) compensation to reduce the effect by about 20 times, and the limit of the test precision due to this coupling is improved to a level of a part in 10~(13).     

Common-mode noise rejection using fringe-locking method in WEP test by simultaneous dual-species atom interferometers

We theoretically investigate the application of the fringe-locking method(FLM) in the dual-species quantum test of the weak equivalence principle(WEP).With the FLM,the measurement is performed invariably at the midfringe,and the extraction of the phase shift for atom interferometers is linearized.For the simultaneous interferometers,this linearization enables a good common-mode rejection of vibration noise,which is usually the main limit for high precision WEP tests of the dual-species kind.We note that this method also allows for an unbiased determination of the gravity accelerations difference,which meanwhile is ready to be implemented.     

Relevance of the weak equivalence principle and experiments to test it: Lessons from the past and improvements expected in space

Tests of the Weak Equivalence Principle (WEP) probe the foundations of physics. Ever since Galileo in the early 1600s, WEP tests have attracted some of the best experimentalists of any time. Progress has come in bursts, each stimulated by the introduction of a new technique: the torsion balance, signal modulation by Earth rotation, the rotating torsion balance. Tests for various materials in the field of the Earth and the Sun have found no violation to the level of about 1 part in 10¹³. A different technique, Lunar Laser Ranging (LLR), has reached comparable precision. Today, both laboratory tests and LLR have reached a point when improving by a factor of 10 is extremely hard. The promise of another quantum leap in precision rests on experiments performed in low Earth orbit. The Microscope satellite, launched in April 2016 and currently taking data, aims to test WEP in the field of Earth to ${10}^{?15}$, a 100-fold improvement possible thanks to a driving signal in orbit almost 500 times stronger than for torsion balances on ground. The ‘Galileo Galilei’ (GG) experiment, by combining the advantages of space with those of the rotating torsion balance, aims at a WEP test 100 times more precise than Microscope, to ${10}^{?17}$. A quantitative comparison of the key issues in the two experiments is presented, along with recent experimental measurements relevant for GG. Early results from Microscope, reported at a conference in March 2017, show measurement performance close to the expectations and confirm the key role of rotation with the advantage (unique to space) of rotating the whole spacecraft. Any non-null result from Microscope would be a major discovery and call for urgent confirmation; with 100 times better precision GG could settle the matter and provide a deeper probe of the foundations of physics.     

Correlation method estimation of the modulation signal in the weak equivalence principle test

In a test of the weak equivalence principle(WEP) with a rotating torsion pendulum, it is important to estimate the amplitude of the modulation signal with high precision. We use a torsional filter to remove the free oscillation signal and employ the correlation method to estimate the amplitude of the modulation signal. The data analysis of an experiment shows that the uncertainties of amplitude components of the modulation signal obtained by the correlation method are in agreement with those due to white noise. The power spectral density of the modulation signal obtained by the correlation method is about one order higher than the thermal noise limit. It indicates that the correlation method is an effective way to estimate the amplitude of the modulation signal and it is instructive to conduct a high-accuracy WEP test.     

Testing fundamental physics with astrophysical transients

Explosive astrophysical transients at cosmological distances can be used to place precision tests of the basic assumptions of relativity theory, such as Lorentz invariance, the photon zero-mass hypothesis, and the weak equivalence principle (WEP). Signatures of Lorentz invariance violations (LIV) include vacuum dispersion and vacuum birefringence. Sensitive searches for LIV using astrophysical sources such as gamma-ray bursts, active galactic nuclei, and pulsars are discussed. The most direct consequence of a nonzero photon rest mass is a frequency dependence in the velocity of light propagating in vacuum. A detailed representation of how to obtain a combined severe limit on the photon mass using fast radio bursts at different redshifts through the dispersion method is presented. The accuracy of the WEP has been well tested based on the Shapiro time delay of astrophysical messengers traveling through a gravitational field. Some caveats of Shapiro delay tests are discussed. In this article, we review and update the status of astrophysical tests of fundamental physics.     

Antihydrogen and fundamental symmetries

The prospects for testing CPT invariance and the weak equivalence principle (WEP) for antimatter with spectroscopic measurements on antihydrogen are discussed. The potential precisions of these tests are compared with those from other measurements. “If there is negative electricity, why not negative gold, as yellow...as our own, with the same boiling point and identical spectrallines...” A. Schuster [1], 1898     

Antihydrogen formation via antiproton scattering on positronium between the $e^{-} +\bar {H}(n = 2)$ and e−+H̄(n=3)$e^{-}+\bar {H}(n = 3)$ thresholds

The charge exchange reaction \(\bar {\mathrm {p}} + \text {Ps} \rightarrow \mathrm {e}^{-} + \bar {\mathrm {H}} \), of interest for the future experiments (GBAR, AEGIS, ATRAP, ...) aiming to produce antihydrogen atoms, is investigated in the energy range between the \(\mathrm {e}^{-}+\bar {\mathrm {H}}(n = 2)\) and \(\mathrm {e}^{-}+\bar {\mathrm {H}}(n = 3)\) thresholds. An ab-initio method based on the solution of the Faddeev-Merkuriev equations is used. Special focus is put on the impact of the Feshbach resonances and the Gailitis-Damburg oscillations, appearing in the vicinity of the \(\bar {\mathrm {p}} +\text {Ps}(n = 2)\) threshold, on the \(\bar {\mathrm {H}}\) production cross section.     

Rotation, the equivalence principle, and the Gravity Probe B experiment

The ultraprecise Gravity Probe B experiment measured the frame-dragging effect and geodetic precession on four quartz gyros. We use this result to test WEP II (weak equivalence principle II) which includes rotation in the universal free-fall motion. The free-fall E?tv?s parameter η for a rotating body is ≤10(-11) with a four-order improvement over previous results. The anomalous torque per unit angular momentum parameter λ is constrained to (-0.05±3.67)×10(-15) s(-1), (0.24±0.98)×10(-15) s(-1), and (0±3.6)×10(-13) s(-1), respectively, in the directions of geodetic effect, frame-dragging effect, and angular momentum axis; the dimensionless frequency-dependence parameter κ is constrained to (1.75±4.96)×10(-17), (1.80±1.34)×10(-17), and (0±3)×10(-14), respectively.     

The application of PCMMcs and SiC by commercially direct dual-complex coating on textile polymer

To enhance the thermal insulation effect, waterproof/breathable fabrics were directly top dual-coated by the dry coating method with ceramic materials (silicon carbide, SiC). The fabric was base coated by the wet coating method with 5 wt% phase-change material microcapsules (PCMMcs) and tested for the emission of far-infrared (FIR) radiation. With increasing SiC content, the fabric altered some of the physical properties by increasing the FIR emissivity, emission power, water vapor transmission rate (WVTR) and heat release capacity. Scanning electron microscopy (SEM) analysis revealed the presence of the PCMMcs and SiC particles at the cross-section and surface of the coating, respectively, which exhibited a rugged and blocky shape. The results indicated that SiC addition did not affect the water entry pressure (WEP) in the fabric structure, but did alter the following physical properties: WVTR, interactions between the macromolecule chains and the susceptibility to humidity.     

AEGIS-K code for linear kinetic analysis of toroidally axisymmetric plasma stability

A linear kinetic stability code for tokamak plasmas: AEGIS-K (Adaptive EiGenfunction Independent Solutions-Kinetic), is described. The AEGIS-K code is based on the newly developed gyrokinetic theory [L.J. Zheng, M.T. Kotschenreuther, J.W. Van Dam, Phys. Plasmas 14 (2007) 072505]. The success in recovering the ideal magnetohydrodynamics (MHD) from this newly developed gyrokinetic theory in the proper limit leads the AEGIS-K code to be featured by being fully kinetic in essence but hybrid in appearance. The radial adaptive shooting scheme based on the method of the independent solution decomposition in the MHD AEGIS code [L.J. Zheng, M.T. Kotschenreuther, J. Comp. Phys. 211 (2006) 748] is extended to the kinetic calculation. A numerical method is developed to solve the gyrokinetic equation of lowest order for the response to the independent solutions of the electromagnetic perturbations, with the quasineutrality condition taken into account. A transform method is implemented to allow the pre-computed Z-function (i.e., the plasma dispersion function) to be used to reduce the integration dimension in the moment calculation and to assure the numerical accuracy in determining the wave–particle resonance effects. Periodic boundary condition along the whole banana orbit is introduced to treat the trapped particles, in contrast to the usual reflection symmetry conditions at the banana tips. Due to the adaptive feature, the AEGIS-K code is able to resolve the coupling between the kinetic resonances and the shear Alfvén continuum damping. Application of the AEGIS-K code to compute the resistive wall modes in ITER is discussed.     

CADF-CSE: Chaotic map-based authenticated data access/sharing framework for IoT-enabled cloud storage environment

Data is an essential asset of an organization or individual in this information age. Secure and resource-efficient data communication has become paramount in the IoT-enabled cloud storage environment. The users must communicate with the cloud storage servers to access, store, and share the data utilizing the public communication channel, which is exposed to various security threats. Moreover, various security frameworks have been presented to render secure data access, storage, and sharing functionalities for the cloud storage environment. Most of them are complicated and incapacitated of resisting various security attacks. Thus, it is imperative to design a secure and resource-efficient data access, storage, and sharing framework for the cloud storage environment. This paper presents a chaotic map-based authenticated data access/sharing framework for the IoT-enabled cloud storage environment (CADF-CSE). CADF-CSE is designed using the chaotic map, authenticated encryption scheme (AEGIS), and one-way hash function (Esch256). The proposed CADF-CSE comprises three significant phases user access control, data storage, and data sharing. The user access control phase enables the user and cloud server to attain mutual authentication followed by the secret session key establishment. Using the established SK during the access control phase user and cloud server exchange information securely across the public Internet. The data storage phase facilitates the data owner to store the data on a cloud server in encrypted form, where encryption is performed with a secret key derived from the user’s biometric. The data-sharing phase enables users to access the data from the cloud server after acquiring mutual permission from the cloud server and the data owner. In addition, an explication of the CADF-CSE through formal and informal analysis shows its resilience to various security attacks. Finally, the performance comparison explicates that CADF-CSE renders better security features while requiring lower computational and communication costs than the related security frameworks.     

Electric field computation inside a rectangular petrol tank

In the paper was developed a hybrid method (analytic–numeric) for the electric field computation inside a rectangular petrol tank. For this problem it will be assumed a static state and all the computations will be developed in a Cartesian coordinate system. Two regions will be delimitated: first one is the free space and second one is the liquid electro-statically charged (petrol) inside the tank.For solving the Laplace equation in the first region, variable separation method will be applied and the electric potential will be determined. In the second region the Poisson equation will be solved, assuming a particular solution and then the electric potential will be obtained. To determine the constants from the potential expressions the zero potential condition at the tank surface and the continuity conditions at the separation surface was considered. Using mathematical manipulations (series development, numerical approximations etc.) an ill conditioned matrix system (23 × 23) resulted. This system will be numerically solved/discussed using a developed MathCad algorithm. The condition number of the coefficients matrix is being computed and the regularization methods applied to the system will be discussed.     

From AMANDA to IceCube

The first string of the neoteric high-energy neutrino telescope IceCube successfully began operating in January 2005. It is anticipated that, upon completion, the new detector will vastly increase the sensitivity and extend the reach of AMANDA to higher energies. A discussion of the IceCube’s discovery potential for extraterrestrial neutrinos, together with the prospects of new physics derived from the ongoing AMANDA research, will be the focus of this paper. Preliminary results of the first antarctic high-energy neutrino telescope AMANDA searching in the muon-neutrino channel for localized and diffuse excess of extraterrestrial neutrinos will be reviewed using data collected between 2000 and 2003. Neutrino flux limits obtained with the all-flavor dedicated ultrahigh energy and cascade analyses will be described. A first neutrino spectrum above 1 TeV in agreement with atmospheric neutrino flux expectations and no extraterrestrial contribution will be presented, followed by a discussion of a limit for neutralino cold dark matter candidates annihilating in the center of the Sun. on behalf of the IceCube Collaboration The text was submitted by the author in English.     

SXRP: an X-ray polarimeter for the SPECTRUM-X-Gamma Mission

Summary TheStellar X-ray Polarimeter (SXRP) is a focal plane instrument which will be flown on the SPECTRUM-X-Gamma mission in 1993. The polarimeter is composed of two separate instruments: the first exploits the dependence on the polarization of the Bragg reflection from a graphite crystal, and of the Thomson scattering from a metallic lithium target. The second instrument makes use of the recently discovered polarization dependence of X-ray photoemission from CsI. The SXRP will permit sensitive measurements of several hundreds of known X-ray sources. X-ray polarization measurements will allow us to constrain the physical mechanisms and the geometries of several classes of galactic X-ray sources, such as X-ray pulsars, black-hole candidates and supernova remnants. Moreover, and for the first time, SXRP will be able to perform highly sensitive measurements of the brightest extragalactic sources. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

多电极半导体光放大器对增益特性的改善

提出了采用多电极实现电流非均匀注入来改变半导体光放大器(SOA)内部的载流子分布,从而改变其增益饱和特性的一种新的方案.用SOA分段模型的计算结果表明,与单电极均匀注入电流的SOA 相比,在同样的总注入电流下,对一个两电极SOA采用前面小后面大的非均匀电流注入,可以提高饱和输出功率和饱和输入功率.而采用前面大后面小的电流注入方式,则将使SOA更容易发生饱和,不仅饱和输出功率与饱和输入功率减小,而且增益谱在饱和后的压缩程度加大,增益谱压缩的对称性提高.对多电极SOA,可以方便灵活地调节各节之间的长度比和注入电流比来满足不同的应用要求.