Photon and axion splitting in an inhomogeneous magnetic field

The axion–photon system in an external magnetic field, when the direction of propagation of axions and photons is orthogonal to the direction of the external magnetic field, displays a continuous axion–photon duality symmetry in the limit the axion mass is neglected. The conservation law that follow in this effective (2+1)$(2+1)$-dimensional theory from this symmetry is obtained. The magnetic field interaction is seen to be equivalent to first order to the interaction of a complex charged field with an external electric potential, where this fictitious “electric potential” is proportional to the external magnetic field. This allows one to solve for the scattering amplitudes using already known scalar QED results. From the scalar QED analog the axion and the photon are symmetric and antisymmetric combinations of particle and antiparticle. If one considers therefore scattering experiments in which the two spatial dimensions of the effective theory are involved nontrivially, one observes that both particle and antiparticle components of photons and axions are preferentially scattered in different directions, thus producing the splitting or decomposition of the photon and axion into their particle and antiparticle components in an inhomogeneous magnetic field. This observable in principle effect is of first order in the axion–photon coupling, unlike the “light shining through a wall phenomena”, which is second order.     

Photon regeneration from pseudoscalars at X-ray laser facilities

Recently, the PVLAS Collaboration reported an anomalously large rotation of the polarization of light in the presence of a magnetic field in vacuum. As a possible explanation, they consider the existence of a light spin-zero particle coupled to two photons. We propose here a method of independently testing this result using a high-energy photon regeneration experiment (the x-ray analogue of "invisible light shining through walls") using the synchrotron x rays from a free-electron laser. With such an experiment the region of parameter space implied by PVLAS could be probed in a matter of minutes.     

EDELWEISS experiment: Direct search for dark matter

The EDELWEISS experiment is aimed at direct searches for nonbaryonic cold dark matter by means of cryogenic germanium detectors. It is deployed at the LSM underground laboratory in the Frejus tunnel, which connects France and Italy. The results of the experimentmade it possible to set a limit on the spin-independent cross section for the scattering of weak-interacting massive particles (WIMP) at a level of 10^?6 pb. Data from 21 detectors of total mass about 7 kg are being accumulated at the present time.     

Measurement of stress using synchrotron x-rays

Stress analysis in polycrystalline materials reveals that stress can vary considerably among different subpopulations of grains. Samples of MgO and mixtures of MgO and spinel have been studied. After the onset of plastic flow, stronger grains or orientations will support more stress than the weaker grains. A grain to grain fabric develops that enables this stress partitioning. The stress partitioning and the resulting fabric can invalidate static measurements of elastic moduli. However, high temperature flow mechanisms reveal a more isotropic strength behaviour resulting in a more uniform variation of stress with orientation.     

A cavity experiment to search for hidden sector photons

We propose a cavity experiment to search for low mass extra U(1) gauge bosons with gauge-kinetic mixing with the ordinary photon, so-called paraphotons. The setup consists of two microwave cavities shielded from each other. In one cavity, paraphotons are produced via photon–paraphoton oscillations. The second, resonant, cavity is then driven by the paraphotons that permeate the shielding and reconvert into photons. This setup resembles the classic “light shining through a wall” setup. However, the high quality factors achievable for microwave cavities and the good sensitivity of microwave detectors allow for a projected sensitivity for photon–paraphoton mixing of the order of χ∼¹⁰⁻¹²–¹⁰⁻⁸$\chi \sim {10}^{\mathrm{-12}}\text{–}{10}^{\mathrm{-8}}$, for paraphotons with masses in the μeV to meV range—exceeding the current laboratory and astrophysics-based limits by several orders of magnitude. Therefore, this experiment bears significant discovery potential for hidden sector physics.     

Model-independent search for new physics at D0 experiment

Finding the evidence of new physics beyond the Standard Model is one of the primary goals of RunII of the Tevatron. Many dedicated searches for new physics are ongoing at the Tevatron but in order to broaden the scope and maximize the chances of finding the new physics, we also search in a model-independent way. The results of such searches for indications of new physics at the electroweak scale are presented using data collected using the D0 detector from $p\bar{p}$ -interactions at $\sqrt {s} = 1.96$ ?TeV.     

Axion search in a monochromatic γ-transition: A new lower limit for the axion mass

A search for axion emission in ¹³⁷Ba¹ was performed, looking for the decay of the a₀'s in two photons. The existence of a₀'s with m_a?160 (200) keV can be excluded with rather mild assumptions.     

Pentaquark search in the NA49 experiment

The NA49 experiment has found narrow peaks in the Ξ^? π ^?, Ξ^? π ⁺ (and antiparticle) spectra at 1862 MeV/c ². These states were identified with the predicted pentaquark cascades. We have searched for other decay channels of the pentaquark cascades. No signal was observed in the ΛK ^? and ΛK _S ⁰ spectra. Based on systematic inconsistencies in the experimental values of the reported Θ⁺, we tried to look for other possible pentaquark states, but observed no signal beyond statistical fluctuations.     

Converters for ultrahard x-rays

A linear theory is constructed to explain the operation of single- and multipass converters for transforming the energy of beam electrons into bremmstrahlung within the spectral interval 10–100 keV (ultrahard x-rays, or UHX-radiation) in a cold-target approximation. Expressions are obtained that make it possible to calculate the spectral and energy characteristics of such radiation. The completed calculations make it possible to give recommendations on choosing target material and thickness and deceleration regimes from the viewpoint of maximizing the output of UHX-radiation energy. Institute of High-Current Electronics, Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 73–78, December, 1995.     

Monopole search with the Mont Blanc LSD experiment

Summary We report here the preliminary results of a search for magnetic monopoles, made with the Liquid Scintillation Detector (LSD) of the Mont Blanc Laboratory, at the depth of 5200 hg/cm² underground. We discuss the detection method and the sensitivity of the experiment to low-energy losses, as expected theoretically for monopoles with low velocity. Since no monopole has been detected we give the upper limit of their flux at Earth for 0 events at the 90% confidence level. This limitF≤6.6·10⁻¹⁴ poles cm⁻²s⁻¹ sr⁻¹ has been obtained after ∼5 months of running time given the large acceptance (SΩ=235 m² sr) of the LSD experiment.

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Riassunto Si riportano i primi risultati di una ricerca sui monopoli magnetici, condotta con l'esperimento LSD (Liquid Scintillation Detector) del Laboratorio del Monte Bianco, alla profondità di 5200 hg/cm² sottoroccia. Si discute il metodo di rivelazione e la sensibilità dell'esperimento a piccole perdite di energia previste teoricamente per monopoli di bassa velocità. Non essendo stati rivelati monopoli si riporta il valore superiore del loro flusso limite a Terra per 0 eventi al 90% livello di confidenza. Questo valore,F≤6.6·10⁻¹⁴ poli cm⁻²s⁻¹sr⁻¹, è stato ottenuto in ∼5 mesi di misura data la grande accettanza dell'esperimento (SΩ=253 m² sr).

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Резюме Мы сообщаем предварительные результаты по поиску магнитных монополей, который был проведен с помощью жидкого сцинтилляционного детектора в лаборатории на Мон Блане, на глубине 5200 гг/см² под землей. Мы обсуждаем метод регистрации и чувствительность эксперимента к потерям энергии в области низких энергий, которые ожидаются теоретически для монополей с низкими скоростями. Так как монополи не были зарегистрированы, мы приводим величину верхнего предела для потока монополей на земле для 0 событий при 90% степени достоверности. Этот предел,F≤6.6·10⁻¹⁴ монополей см⁻² с⁻¹ ср⁻¹, был получен после 5 месяцев работы жидкого сцинтилляцичоного детектора с большим акцептансом (SΩ=253 м² ср).

     

Limits for axion emission in nuclear deexcitation processes

Abstract The question of the emission of pseudoscalar bosons (axions) in nuclear deexcitation processes and their decay into two photons was studied with a rotatable multi detector system at the power reactor Biblis A. Assuming an axion mass of 250 keV and the standard model decay rate we obtain (1.0 ± 1.0) × 1O^?10 for the ratio of the numbers of axions and Ml γ- ray transitions in the reactor core. This is ～ 10^?5 of the model prediction.     

Results of the development of the technique for using nuclear photoemulsions in the experiment on the search for double neutrinoless beta decay

The last results on the preparation of the experiment on the search for double neutrinoless decay using emulsion chambers with molybdenum filling are presented. The results of testing emulsions prepared by the OJSC “Slavich Company” are presented. Algorithms for recognizing electron tracks in rectilinear and curvilinear portions are described.