Production of relativistic positronium in collisions of photons and electrons with nuclei and atoms

We consider the production of ultrarelativistic positronium (Ps) in $\gamma A \to Ps + A$ and $e A \to Ps + e A$ processes where $A$ is an atom or a nucleus with charge $Ze$. For the photoproduction of para- and ortho-Ps and the electroproduction of para-Ps we obtain the most complete description compared with previous works. It includes high order $Z \alpha$ corrections and polarization effects. The accuracy of the obtained cross sections is determined by omitted terms of the order of the inverse Ps Lorentz factor squared. The studied high order multi-photon electroproduction of ortho-Ps dominates for the collision of electrons with heavy atoms over the bremsstrahlung production from the electron via a virtual photon proposed by Holvik and Olsen. Our results complete and correct the studies of those authors.Comment: 19 pages, 9 figures, RevTex; v2: minor corrections for the accuracy of the results, a discussion of the literature added in a footnote, one additional reference; v3: diagram of Fig.2 correcte

Production of para-- and orthopositronium at relativistic heavy ion colliders

We consider the ortho-- and parapositronium production in the process $AA \to AA+$ Ps where A is a nucleus with the charge number Z. The inclusive cross section and the energy distribution of the relativistic Ps are calculated which are of primary interest from the experimental point of view. The accuracy of the corresponding cross sections is given by omitting terms $\sim (Z\alpha )^2/L^2$ for the para--Ps and $\sim (Z\alpha)^2/L$ for the ortho--Ps production where $L=\ln{\gamma^2} \approx 9$ and 16 for the RHIC and the LHC. Within this accuracy the multiphoton (Coulomb) corrections are taken into account. We show that the RHIC and the LHC will be Ps factories with a productions rate of about $10^5 \div 10^8$ relativistic Ps per day. The fraction of the ortho--Ps is expected to be of the same order as that of the para--Ps for Au--Au and Pb--Pb collisions.Comment: 22 pages, 5 figures, RevTeX, misprint correcte

ALMA Band 5 receiver cartridge. Design, performance, and commissioning

We describe the design, performance, and commissioning results for the new ALMA Band 5 receiver channel, 163–211 GHz, which is in the final stage of full deployment and expected to be available for observations in 2018. This manuscript provides the description of the new ALMA Band 5 receiver cartridge and serves as a reference for observers using the ALMA Band 5 receiver for observations. At the time of writing this paper, the ALMA Band 5 Production Consortium consisting of NOVA Instrumentation group, based in Groningen, NL, and GARD in Sweden have produced and delivered to ALMA Observatory over 60 receiver cartridges. All 60 cartridges fulfil the new more stringent specifications for Band 5 and demonstrate excellent noise temperatures, typically below 45 K single sideband (SSB) at 4 K detector physical temperature and below 35 K SSB at 3.5 K (typical for operation at the ALMA Frontend), providing the average sideband rejection better than 15 dB, and the integrated cross-polarization level better than –25 dB. The 70 warm cartridge assemblies, hosting Band 5 local oscillator and DC bias electronics, have been produced and delivered to ALMA by NRAO. The commissioning results confirm the excellent performance of the receivers

"Equivalent photon approximation. Range of validity, accuracy, etc."

This review is devoted mainly to the two-photon production. We begin with a description of this method. The necessity of such an introduction is, in particular, due to some errors or inaccurate statements when using this method in some papers, and too complicated formulas and methods used in other ones. Apart from the known formulas, a number of new results which are useful for experiment are provided, e. g. a simple and convenient method of estimation of the approximation accuracy. A special appendix is devoted to an analysis of a few errors and inaccurate statements contained in papers of Brodsky, Kinoshita and Terazawa (1970), Greco (1971), Cheng and Wu (1971), Bonneau, Gourdin and Martin (1972), etc

"Two-photon production of leptons and search of new particles"

This review is devoted to the following problems : 1. Some little-known applications and effects connected with the two-photon e+ e–-pair production : energy losses of fast muons in the matter ; the investigation of π and K form factors ; the possibility to calibrate accelerators with the colliding pp, p[MATH] or ep beams ; measuring the high energy photon polarization, measuring the real part of proton Compton effect, etc. 2. Somme processes of high order in α for the electron storage rings having cross section high enough, two e+ e–-pair production (ee → eee+ e– e+ e–) ; parapositronium production ; production of photons with MeV energy for large emission angles. 3. The search of new particles: intermediate vector mesons, Dirac's monopols and massive leptons. 4. Some questions of the two-photon massive µ-pair production

"Hadron production in electron-positron storage rings", a review

This review is devoted to the three general problems : 1. Physics of the process γγ → h (hadrons). 2. Methods of extracting the information on the process γγ → h. 3. The other channels of the hadron production and background. In the section concerning physics of the process γγ → h, we limit ourselves to a short consideration of interesting reaction channels and domains of variables (photon "masses" and their summary energy) and review the principal theoretical ideas. The problem of extracting the information on the process γγ → h is a central one in the review. Different versions of the experimental set-ups both associated with recording the scattered electrons and without it are considered here in detail. The simple approximate expressions are obtained for corresponding contributions to the cross section. In conclusion, various sources of the background are listed and the corresponding estimates are given