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1.
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The $\pi^+\pi^-$ Coulomb interaction study and its use in the data processing
/ Adeva, B. (Santiago de Compostela U.) ; Afanasyev, L. (Dubna, JINR) ; Anania, A. (INFN, Messina) ; Aogaki, S. (Bucharest, IFIN-HH) ; Benelli, A. (Prague, Tech. U.) ; Brekhovskikh, V. (Serpukhov, IHEP) ; Cechak, T. (Prague, Tech. U.) ; Chiba, M. (Tokyo Metropolitan U.) ; Chliapnikov, P. (Serpukhov, IHEP) ; Drijard, D. (Prague, Tech. U. ; CERN) et al.
In this work the Coulomb effects (Coulomb correlations) were studied using experimental $\pi^+\pi^-$ pair distributions in $Q$, the relative momentum in the pair center of mass system (c.m.s), and its projections $Q_L$ (longitudinal component) and $Q_t$ (transverse component) relative to the pair direction in the laboratory system (l.s.). The major part of the pion pairs is produced by decay of $\rho, \omega$ and $\Delta$ and other short-lived sources (Coulomb pairs). [...]
arXiv:2409.12696; CERN-EP-2023-276.-
Geneva : CERN, 2024-11-01 - 11 p.
- Published in : Phys. Rev. D 110 (2024) 092005
Draft (restricted): PDF; Fulltext: DIRAC-Coulomb-correct - PDF; 2409.12696 - PDF;
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2.
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Investigation of $K^+K^-$ pairs in the effective mass region near $2m_K$
/ DIRAC Collaboration
The DIRAC experiment at CERN investigated in the reaction $\rm{p}(24~\rm{GeV}/c) + Ni$ the particle pairs $K^+K^-, \pi^+ \pi^-$ and $p \bar{p}$ with relative momentum $Q$ in the pair system less than 100 MeV/c. Because of background influence studies, DIRAC explored three subsamples of $K^+K^-$ pairs, obtained by subtracting -- using time-of-flight (TOF) technique -- background from initial $Q$ distributions with $K^+K^-$ sample fractions more than 70%, 50% and 30%. [...]
arXiv:2204.01857; CERN-EP-2022-058.-
2022-08-01 - 18 p.
- Published in : Phys. Rev. D 106 (2022) 032006
Fulltext: PhysRevD.106.032006 - PDF; 2204.01857 - PDF;
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3.
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First measurement of a long-lived $\pi^+ \pi^-$ atom lifetime
/ DIRAC Collaboration
The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogen-like $\pi^+\pi^-$ atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96~mm and got broken up in the 2.1~\textmu{}m thick platinum foil. [...]
arXiv:1811.08659; CERN-EP-2018-281; DIRAC-PUB-2019-01.-
Geneva : CERN, 2019-03-01 - 7 p.
- Published in : Phys. Rev. Lett. 122 (2019) 082003
Article from SCOAP3: PDF; Draft (restricted): PDF; Fulltext: 1811.08659 - PDF; CERN-EP-2018-281 - PDF;
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4.
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Measurement of the $\pi K$ atom lifetime and the $\pi K$ scattering length
/ DIRAC Collaboration
After having announced the statistically significant observation (5.6~$\sigma$) of the new exotic $\pi K$ atom, the DIRAC experiment at the CERN proton synchrotron presents the measurement of the corresponding atom lifetime, based on the full $\pi K$ data sample: $\tau = (5.5^{+5.0}_{-2.8}) \cdot 10^{-15}s$. By means of a precise relation ($<1\%$) between atom lifetime and scattering length, the following value for the S-wave isospin-odd $\pi K$ scattering length $a_0^{-}~=~\frac{1}{3}(a_{1/2}-a_{3/2})$ has been derived: $\left|a_0^-\right| = (0.072^{+0.031}_{-0.020}) M_{\pi}^{-1}$..
arXiv:1707.02184; CERN-EP-2017-137; DIRAC-PUB-2017-01.-
Geneva : CERN, 2017-09-19 - 18 p.
- Published in : Phys. Rev. D 96 (2017) 052002
Draft (restricted): PDF; Fulltext: CERN-EP-2017-137 - PDF; arXiv:1707.02184 - PDF; Fulltext from publisher: PDF;
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5.
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Observation of $\pi^- K^+$ and $\pi^+ K^-$ atoms
/ DIRAC Collaboration
The observation of hydrogen-like $\pi K$ atoms, consisting of $\pi^- K^+$ or $\pi^+ K^-$ mesons, is presented. The atoms have been produced by 24 GeV/$c$ protons from the CERN PS accelerator, interacting with platinum or nickel foil targets. [...]
arXiv:1605.06103; CERN-EP-2016-128; DIRAC-PUB-2016-02.-
Geneva : CERN, 2016-09-08 - 6 p.
- Published in : Phys. Rev. Lett. 117 (2016) 112001
Draft (restricted): PDF; Fulltext: arXiv:1605.06103 - PDF; 10.1103_PhysRevLett.117.112001 - PDF; PhysRevLett.117.112001 - PDF; Preprint: PDF; External link: Fulltext
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6.
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First observation of long-lived $\pi^+ \pi^-$ atoms
/ DIRAC Collaboration
After observing and investigating the double-exotic $\pi^+\pi^-$ atom with the ground state lifetime $\tau$ of about $3 \times 10^{-15}$~s, the upgraded DIRAC experiment at the CERN PS accelerator observes for the first time long-lived states of the same atom with lifetimes of about $10^{-11}$~s and more. The number of characteristic pion pairs resulting from the breakup (ionisation) of long-lived $\pi^+\pi^-$ atoms amounts to $436\pm61$, corresponding to a signal-to-error ratio of better than 7 standard deviations. [...]
arXiv:1508.04712; CERN-PH-EP-2015-175; DIRAC-PUB-2015-02; CERN-PH-EP-2015-175.-
Geneva : CERN, 2015-09-26 - 13 p.
- Published in : Phys. Lett. B 751 (2015) 12-18
Article from SCOAP3: plb-751-12 - PDF; scoap3-fulltext - PDF; Fulltext: PDF; External link: Preprint
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7.
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Updated DIRAC spectrometer at CERN PS for the investigation of ππ and πK atoms
/ PS212 collaboration
The DIRAC spectrometer installed at CERN PS was redesigned and upgraded in order to study simultaneously Aππ and AπK atoms, namely the bound states of π+π–, and π+K–, π–K+ mesons. The detector system which is able to accept a high intensity beam such as 2 - 6 × 1011 primary protons per second, the electronics and the data-acquisition system adapted to handle very large amount of data actually allowed to identify successfully π, K, p, e and µ and to give the possibility to select π-π and π-K pairs in the off-line analysis. [...]
CERN-PH-EP-2015-147; DIRAC-PUB-2016-03.-
Geneva : CERN, 2016 - 34 p.
- Published in : Nucl. Instrum. Methods Phys. Res., A 839 (2016) 52-85
Draft (restricted): PDF; Fulltext: PDF;
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8.
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First $\pi K$ atom lifetime and $\pi K$ scattering length measurements
/ DIRAC Collaboration
The results of a search for hydrogen-like atoms consisting of $\pi^{\mp}K^{\pm}$ mesons are presented. Evidence for $\pi K$ atom production by 24 GeV/c protons from CERN PS interacting with a nickel target has been seen in terms of characteristic $\pi K$ pairs from their breakup in the same target ($178 \pm 49$) and from Coulomb final state interaction ($653 \pm 42$). [...]
arXiv:1403.0845; CERN-PH-EP-2014-030; DIRAC-PUB-2014-01; CERN-PH-EP-2014-030.-
Geneva : CERN, 2014-07-30 - 7 p.
- Published in : Phys. Lett. B 735 (2014) 288-294
Article from SCOAP3: PDF; Draft (restricted): PDF; Fulltext: PDF; Preprint: PDF;
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9.
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Beta Beams for Precision Measurements of Neutrino Oscillation Parameters
/ Wildner, E (CERN) ; Benedetto, E (CERN) ; Hansen, C (CERN) ; De Melo Mendonca, T (CERN) ; Stora, T (CERN) ; Damjanovic, S (CERN) ; Payet, J (Saclay) ; Chancé, A (Saclay) ; Zorin, V (Nizhnii Novgorod, IAP) ; Izotov, I (Nizhnii Novgorod, IAP) et al.
Neutrino oscillations have implications for the Standard Model of particle physics. The CERN Beta Beam has outstanding capabilities to contribute to precision measurements of the parameters governing neutrino oscillations [...]
CERN-ATS-2012-145.-
Geneva : CERN, 2012 - 3 p.
- Published in : Conf. Proc.: C1205201 (2012) , pp. THPPP087
Fulltext: PDF; External link: Published version from JaCoW
In : 3rd International Particle Accelerator Conference, New Orleans, LA, USA, 20 - 25 May 2012, pp.3939
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10.
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Beta Beams: an accelerator based facility to explore Neutrino oscillation physics
/ Wildner, E (CERN) ; Benedetto, E (CERN) ; Hansen, C (CERN) ; De Melo Mendonca, T (CERN) ; Stora, T (CERN) ; Payet, J (Saclay) ; Chance, A (Saclay) ; Zorin, V (Nizhnii Novgorod, IAP) ; Izotov, I (Nizhnii Novgorod, IAP) ; Rasin, S (Nizhnii Novgorod, IAP) et al.
The discovery that the neutrino changes flavor as it travels through space has implications for the Standard Model of particle physics (SM)[1]. To know the contribution of neutrinos to the SM, needs precise measurements of the parameters governing the neutrino oscillations. [...]
CERN-ATS-2011-182.-
Geneva : CERN, 2011 - 3 p.
Fulltext: PDF; External link: Published version from JACoW
In : 2nd International Particle Accelerator Conference, San Sebastian, Spain, 4 - 9 Sep 2011, pp.WEPS024
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