A search for photonless annihilation of orthopositronium

Atoyan, G. S.; Gninenko, S.; Razin, V. I.; Ryabov, Yu. V.

doi:10.1016/0370-2693(89)90059-2

Cited by 39 publications

(20 citation statements)

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“…Although Atoyan et ai [11] performed a similar experiment that obtained an upper limit on the branching ratio of 580 ppm, their method necessitated applying a large background subtraction (20000 minus 20000 ppm), where a small change in background between the real and dummy targets could result in error. In contrast, here a thick hermetic photon detector is used to completely eliminate the background of the two escaping photons, hence enabling us to reach a sensitivity 200 times better than Atoyan et al We should then be able to conclude, without any ambiguity, whether the invisible decay or the conversion is the origin of the decay rate discrepancy.…”

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confidence: 99%

Search for invisible decay of orthopositronium

et al. 1993

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Orthopositronium (o-Ps) decay or conversion into "invisible" final states is searched for by measuring the energy deposited in a hermetic photon detector for each positron produced from p + decay of 22 Na and stopped by an aerogel target. No invisible event is detected for a total of 10 8 stopping positrons, thereby giving an upper limit of 2.8xl0 -6 on the o-Ps branching ratio, which is 200 times more stringent than previous limits. This experiment excludes an invisible decay as the origin of the reported discrepancy on o-Ps lifetime, provides a limit of e < 1.5 x 10 ~~8 on the photon-mirror-photon mixing, and rules out millicharged particles lighter than 500 keV.

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confidence: 99%

Search for invisible decay of orthopositronium

et al. 1993

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“…It is generally accepted that the low energy emission (from radio to UV or, in some cases, X-rays) is generated via synchrotron radiation by relativistic electrons in the jet plasma, while high-energy emission (from X-ray to γ rays) is the result of inverse Compton scattering of seed photons by the same population of relativistic electrons. The seed photons could be either synchrotron photons generated in the jet (synchrotron selfCompton model; e.g., Atoyan & Nahapetian 1989;Marscher 2014) or ambient photons (external Compton model; Begelman & Sikora 1987;Tavecchio et al 2010). Several models have been proposed regarding the location of the γ-ray emission site relative to the central engine in blazars.…”

Section: Introductionmentioning

confidence: 99%

Connection between parsec-scale radio jet and gamma-ray flares in the blazar 1156+295

Rastorgueva-Foi¹,

Wiik²,

Jorstad³

et al. 2015

Proceedings of 12th European VLBI Network Symposium and Users Meeting — PoS(EVN 2014)

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The blazar 1156+295 was active at γ-ray energies, exhibiting three prominent flares during the year 2010. Here, we present results using the combination of broadband (X-ray through mm single dish) monitoring data and radio band imaging data at 43 GHz on the connection of γ-ray events to the ejections of superluminal components and other changes in the jet of 1156+295. The kinematics of the jet over the interval 2007.0-2012.5 using 43 GHz Very Long Baseline Array observations, reveal the presence of four moving and one stationary component in the inner region of the blazar jet. The propagation of the third and fourth components in the jet corresponds closely in time to the active phase of the source in γ rays. We briefly discuss the implications of the structural changes in the jet for the mechanism of γ-ray production during bright flares. To localise the γ-ray emission site in the blazar, we performed the correlation analysis between the 43 GHz radio core and the γ-ray light curve. The time lag obtained from the correlation constrains the γ-ray emitting region in the parsec-scale jet.

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“…The first experiment on the o − P s → invisible decay, motivated by a puzzle in the o − P s decay rate (see below), was performed a long time ago [34], and then repeated with higher sensitivity [35]. The results exclude contributions to the o − P s decay rate from invisible decay modes (such as o − P s → νν, millicharged particles, etc..) at the level of Br(o − P s → invisible) < 3 · 10 −6 , but are not very sensitive to the o − P s → o − P s ′ oscillation mechanism because of the high collision rate in these experiments.…”

Section: Introductionmentioning

confidence: 99%

An Apparatus to Search for Mirror Dark Matter

Gninenko

2004

Int. J. Mod. Phys. A

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Mirror matter is a possible dark matter candidate. It is predicted to exist if parity is an unbroken symmetry of the vacuum. The existence of the mirror matter, which in addition to gravity is coupled to our world through photon-mirror photon mixing, would result in orthopositronium (o − P s) to mirror orthopositronium (o − P s ′ ) oscillations. The experimental signature of this effect is the invisible decay of o − P s in vacuum. This paper describes the design of the new experiment for a search for the o−P s → invisible decay in vacuum with a sensitivity in the branching ratio of Br(o − P s → invisible) ≃ 10 −7 , which is an order of magnitude better than the present limit on this decay mode from the Big Bang Nucleosynthesis. The experiment is based on a high-efficiency pulsed slow positron beam, which is also applicable for other experiments with o − P s, and (with some modifications) for applied studies. Details of the experimental design and of a new pulsing method, as well as preliminary results on requirements for the pulsed beam components are presented. The effects of o − P s collisions with the cavity walls as well as the influence of external fields on the o − P s → o − P s ′ oscillation probability are also discussed.

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A search for photonless annihilation of orthopositronium

Cited by 39 publications

References 4 publications

Search for invisible decay of orthopositronium

Search for invisible decay of orthopositronium

Connection between parsec-scale radio jet and gamma-ray flares in the blazar 1156+295

An Apparatus to Search for Mirror Dark Matter

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