Upgraded DIRAC spectrometer at CERN PS for the investigation of ππ and πK atoms

Adeva, B.; Afanasyev, L.; Allkofer, Y.; Amsler, C.; Anania, A.; Aogaki, S.; Benelli, A.; Brekhovskikh, V.; Caragheorgheopol, G.; Čechák, T.; Chiba, M.; Chliapnikov, P.; Ciocarlan, C.; Constantinescu, S.; Detraz, C.; Doskarova, P.; Drijard, D.; Dudarev, A.; Dūma, M.; Dumitriu, D.; Flueraşu, D.; Gorin, A.; Gorchakov, O.E.; Gritsay, K.; Guaraldo, C.; Gugiu, M.; Hansroul, M.; Hons, Z.; Horikawa, S.; Iwashita, Yoshihisa; Karpukhin, V.V.; Kluson, J.; Kobayashi, M.; Kruglov, V.V.; Kruglova, L.; Kulikov, A.; Kulish, E.; Kuptsov, A.V.; Lamberto, A.; Lanaro, A.; Lednický, R.; Mariñas, C.; Martincik, J.; Nemenov, L.L.; Nikitin, M.; Okada, K.; Olchevskii, V.; Pentia, M.; Penzo, A.; Pló, M.; Průša, P.; Rappazzo, G. F.; Vidal, A. Romero; Ryazantsev, A.; Rykalin, V.I.; Saborido, J.; Schacher, J.; Sidorov, A.; Smolík, J.; Takéutchi, F.; Tauscher, L.; Trojek, T.; Trusov, S.; Ullaland, O.; Urban, T.; Vrba, T.; Yazkov, V.; Yoshimura, Y.; Zhabitsky, M.; Zrelov, P.

doi:10.1016/j.nima.2016.07.049

Cited by 7 publications

(2 citation statements)

References 19 publications

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“…The apparatus [8] sketched in Fig. 1 detects and identifies π + π − , π − K + and π + K − pairs with small Q.…”

Section: Methodsmentioning

confidence: 99%

First observation of Ï€-K+ and Ï€+K- atoms, their lifetime measurement and Ï€K scattering lengths evaluation.

Afanasyev¹

2017

Proceedings of 38th International Conference on High Energy Physics — PoS(ICHEP2016)

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The Low Energy QCD allows to calculate the ππ and πK scattering lengths with high precision. There are accurate relations between these scattering lengths and π + π − , π − K + , π + K − atoms lifetimes. The experiment on the first observation of π − K + and π + K − atoms is described. The atoms were generated in Nickel and Platinum targets hit by the PS CERN proton beam with momentum of 24 GeV/c. Moving in the target, part of atoms break up producing characteristic πK pairs (atomic pairs) with small relative momentum Q in their c.m.s. In the experiment, we detected n A = 349 ± 62 (5.6 standard deviations) π − K + and π + K − atomic pairs. The main part of πK pairs are produced in free state. The majority of such particles are generated directly or from short-lived sources as ρ, ω and similar resonances. The electromagnetic interactions in the final state create Coulomb pairs with a known sharp dependence on Q. This effect allows to evaluate the number of these Coulomb pairs. There is a precise ratio (∼1%) between the number of π − K + (π + K − ) Coulomb pairs with small Q and the number of produced π − K + (π + K − ) atoms. Using this ratio, we obtained the numbers of generated π − K + and π + K − atoms. The atom breakup probability in a target P br = n A /N A depends on the atom lifetime. Using such dependences for the Ni and Pt targets, known with a precision about 1%, the πK atom lifetime was measured and from this value the πK scattering lengths were evaluated. The presented analysis shows that the π − K + and π +

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“…The apparatus [8] sketched in Fig. 1 detects and identifies π + π − , π − K + and π + K − pairs with small Q.…”

Section: Methodsmentioning

confidence: 99%

First observation of Ï€-K+ and Ï€+K- atoms, their lifetime measurement and Ï€K scattering lengths evaluation.

Afanasyev¹

2017

Proceedings of 38th International Conference on High Energy Physics — PoS(ICHEP2016)

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“…In 2004-2006 it has been modified in order to detect both π + π − and πK pairs [18]. New detectors for particle identification have been added: Cherenkov detectors with heavy gas and aerogel for identification of K-mesons among background of pions and protons, correspondingly.…”

Section: Dirac Setupmentioning

confidence: 99%

Observation and investigation ofπKatoms

Yazkov

2017

EPJ Web Conf.

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Abstract. There is accurate relation between lifetime of atoms, consisting of pion and kaon, and a difference of S-wave pion kaon scattering length with isospin 1/2 and 3/2: |a 1/2 − a 3/2 |. This difference is predicted by low energy QCD. Experiment DIRAC at CERN PS detects 349 ± 62 pairs from K + π − and π + K − atoms and make observation of exotic atoms consist of pion and kaons and provides way for measurement of pion-kaon scattering length difference and check of theoretical predictions.

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Observation of π⁻K⁺ and π⁺K⁻ atoms

Yazkov

2018

EPJ Web of Conferences

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Abstract. Experiment DIRAC at CERN PS detects 349 ± 62 pairs from π − K + and π + K − atoms and makes observation of exotic atoms consist of pion and kaon. It allows to measure a difference of S-wave pion-kaon scattering length with isospin 1/2 and 3/2: |a 1/2 0 − a 3/2 0 |. Values of pion-kaon scattering lengths are predicted in a frame of ChPT and LQCD. Therefore investigation of π − K + and π + K − atoms gives possibility to check these predictions for simplest hadronhadron system with s-quark.

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Upgraded DIRAC spectrometer at CERN PS for the investigation of ππ and πK atoms

Abstract: The DIRAC spectrometer installed at CERN PS was redesigned and upgraded in order to study simultaneously A ππ and A πK atoms, namely the bound states of π

Cited by 7 publications

References 19 publications

First observation of Ï€-K+ and Ï€+K- atoms, their lifetime measurement and Ï€K scattering lengths evaluation.

First observation of Ï€-K+ and Ï€+K- atoms, their lifetime measurement and Ï€K scattering lengths evaluation.

Observation and investigation ofπKatoms

Observation of π⁻K⁺ and π⁺K⁻ atoms

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Upgraded DIRAC spectrometer at CERN PS for the investigation of ππ and πK atoms

Abstract: The DIRAC spectrometer installed at CERN PS was redesigned and upgraded in order to study simultaneously A ππ and A πK atoms, namely the bound states of π

Cited by 7 publications

References 19 publications

First observation of Ï€-K+ and Ï€+K- atoms, their lifetime measurement and Ï€K scattering lengths evaluation.

First observation of Ï€-K+ and Ï€+K- atoms, their lifetime measurement and Ï€K scattering lengths evaluation.

Observation and investigation ofπKatoms

Observation of π−K+ and π+K− atoms

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Observation of π⁻K⁺ and π⁺K⁻ atoms