N. Akopov

Measurement of the Spin-Dependence of the pbar-p Interaction at the AD-Ring (2009)

Barschel, C, Bechstedt, U, Dietrich, J, Dolfus, N, Engels, R, Gebel, R, ...

We propose to use an internal polarized hydrogen storage cell gas target in the AD ring to determine for the first time the two total spin-dependent pbar-p cross sections sigma_1 and sigma_2 at...

Measurement of the Spin-Dependence of the pbar-p Interaction at the AD-Ring (2009)

Barschel, C., Bechstedt, U., Dietrich, J., Dolfus, N., Engels, R., Gebel, R., ...

We propose to use an internal polarized hydrogen storage cell gas target in the AD ring to determine for the first time the two total spin-dependent pbar-p cross sections sigma_1 and sigma_2 at...

Measurement of the Spin–Dependence of the $\overline{p}-p$ Interaction at the AD–Ring (2009)

Barschel, C, Bechstedt, U, Dietrich, J, Dolfus, N, Engels, R, Gebel, R, ...

We propose to use an internal polarized hydrogen storage cell gas target in the AD ring to determine for the first time the two total spin–dependent pbar-p cross sections σ1 and σ2 at antiproton...

Observation of the Naive-T-odd Sivers Effect in Deep-Inelastic Scattering (2009)

HERMES Collaboration, DESY Forschung Hochenergiephysik, A. Airapetian, N. Akopov, Z. Akopov, E.C. Aschenauer, ...

Internal report | Preprint

Transverse momentum broadening of hadrons produced in semi-inclusive deep-inelastic scattering on nuclei (2009)

HERMES Collaboration, DESY Forschung Hochenergiephysik, A. Airapetian, N. Akopov, Z. Akopov, E.C. Aschenauer, ...

Internal report | Preprint

Exclusive rho-0 electroproduction on transversely polarized protons (2009)

HERMES Collaboration, DESY Forschung Hochenergiephysik, A. Airapetian, N. Akopov, Z. Akopov, E.C. Aschenauer, ...

Internal report | Preprint

Single-spin azimuthal asymmetry in exclusive electroproduction of π+ mesons on transversely polarized protons (2009)

A. Airapetian, DESY Forschung Hochenergiephysik, N. Akopov, Z. Akopov, E.C. Aschenauer, W. Augustyniak, ...

Internal report | Preprint

Search for a Two-Photon Exchange Contribution to Inclusive Deep-Inelastic Scattering (2009)

A. Airapetian, DESY Forschung Hochenergiephysik, N. Akopov, Z. Akopov, E.C. Aschenauer, W. Augustyniak, ...

Internal report | Preprint

Spin density matrix elements in exclusive ρ0 electroproduction on 1H and 2H targets at 27.5 GeV beam energy (2009)

A. Airapetian, DESY Forschung Hochenergiephysik, N. Akopov, Z. Akopov, A. Andrus, E.C. Aschenauer, ...

Journal article

Exclusive ρ0 electroproduction on transversely polarized protons (2009)

A. Airapetian, DESY Forschung Hochenergiephysik, N. Akopov, Z. Akopov, E.C. Aschenauer, W. Augustyniak, ...

Journal article

Separation of contributions from deeply virtual Compton scattering and its interference with the Bethe-Heitler process in measurements on a hydrogen target (2009)

The HERMERS Collaboration, DESY Forschung Hochenergiephysik, A. Airapetian, N. Akopov, Z. Akopov, E.C. Aschenauer, ...

Internal report | Preprint

Observation of the Naive-T-odd Sivers Effect in Deep-Inelastic Scattering (2009)

HERMES Collaboration, DESY Forschung Hochenergiephysik, A. Airapetian, N. Akopov, Z. Akopov, E.C. Aschenauer, ...

Journal article

Measurement of azimuthal asymmetries associated with deeply virtual Compton scattering on an unpolarized deuterium target (2009)

A. Airapetian, DESY Forschung Hochenergiephysik, N. Akopov, Z. Akopov, M. Amarian, E.C. Aschenauer, ...

Internal report | Preprint

Nuclear-mass dependence of azimuthal beam-helicity and beam-charge asymmetries in deeply virtual Compton scattering (2009)

A. Airapetian, DESY Forschung Hochenergiephysik, N. Akopov, Z. Akopov, M. Amarian, E.C. Aschenauer, ...

Internal report | Preprint

Possible scaling behaviour of the multiplicities ratio in leptoproduction of charged pions in nuclear medium (2008)

Akopov, N., Grigoryan, L., Akopov, Z.

In this paper it is demonstrated that based on two-dimensional distributions in semi-inclusive deep inelastic scattering (SIDIS) data, obtained recently by the HERMES experiment at DESY on different...

Cross sections for hard exclusive electroproduction of pi(+) mesons on a hydrogen target (2008)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, ASCHENAUER, EC, AUGUSTYNIAK, W, AVETISSIAN, A, ...

Spin Density Matrix Elements in Exclusive rho-0 Electroproduction on 1H and 2H Targets at 27.6 GeV Beam Energy (2008)

HERMES Collaboration, DESY Forschung Hochenergiephysik, A. Airapetian, N. Akopov, Z. Akopov, A. Andrus, ...

Internal report | Preprint

Measurement of parton distributions of strange quarks in the nucleon from charged-kaon production in deep-inelastic scattering on the deuteron (2008)

Airapetian, A, Akopov, N, Akopov, Z, Bruell, A, Elschenbroich, U, Hommez, B, ...

The momentum and helicity density distributions of the strange quark sea in the nucleon are obtained in leading order from charged-kaon production in deep-inelastic scattering on the deuteron. The...

Evidence for a transverse single-spin asymmetry in leptoproduction of pi(+)pi(-) pairs (2008)

Airapetian, A, Akopov, N, Akopov, Z, Elschenbroich, U, Hommez, B, Maiheu, B, ...

A single-spin asymmetry was measured in the azimuthal distribution of pi(+)pi(-) pairs produced in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target. For the first...

Measurement of azimuthal asymmetries with respect to both beam charge and transverse target polarization in exclusive electroproduction of real photons (2008)

Airapetian, A, Akopov, N, Akopov, Z, Elschenbroich, U, Joosten, S, Maiheu, B, ...

Azimuthal asymmetries in exclusive electroproduction of real photons are measured for the first time with respect to transverse target polarisation, providing new constraints on Generalized Parton...

Measurement of azimuthal asymmetries with respect to both beam charge and transverse target polarization in exclusive electroproduction of real photons (2008)

Airapetian, A., Akopov, N., Akopov, Z., Andrus, A., Aschenauer, E.C., ...

"Azimuthal asymmetries in exclusive electroproduction of real photons are measured for the first time with respect to transverse target polarisation, providing new constraints on Generalized Parton...

Performance of the Electromagnetic Calorimeter of the HERMES Experiment (2007)

Avakian Bianchi, N. Bianchi, G. P. Capitani, E. De Sanctis, P. Di Nezza, A. Fantoni, ...

The performance of the electromagnetic calorimeter of the HERMES experiment is described. The calorimeter consists of 840 radiation resistant F101 lead-glass counters. The response to positrons up to...

The HERMES Spectrometer (2007)

K. Ackerstaff, A. Airapetian, N. Akopov, H. Avakian, V. Andreev, ...

The HERMES experiment is collecting data on inclusive and semi-inclusive deep inelastic scattering of polarised positrons from polarised targets of H, D, and 3 He. These data give information on the...

$A$-dependence of coherent electroproduction of $\rho^{0}$ mesons on nuclei in forward direction (2007)

Akopov, N., Akopov, Z., Aslanyan, G., Grigoryan, L.

This article presents the $A$-dependence of the differential cross section for the coherent electroproduction of vector mesons on nuclei in forward direction, at fixed values of longitudinal momentum...

Possible influence of the two string events on the hadron formation in a nuclear environment (2007)

Akopov, N., Grigoryan, L., Akopov, Z.

One of the basic assumptions of the string model is that as a result of a DIS in nucleus a single string arises, which then breaks into hadrons. However the pomeron exchange considered in this work,...

Simple parameterization of nuclear attenuation data (2007)

Akopov, N., Grigoryan, L., Akopov, Z.

Based on the nuclear attenuation data obtained by the HERMES experiment on nitrogen and krypton nuclei, it is shown that the nuclear attenuation $R_M^{h}$ can be parametrised in a form of a linear...

Beam-charge azimuthal asymmetry and deeply virtual Compton scattering (2007)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z

Precise determination of the spin structure function g(1) of the proton, deuteron, and neutron (2007)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z

Hadronization in semi-inclusive deep-inelastic scattering on nuclei (2007)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, ASCHENAUER, EC, AUGUSTYNIAK, W, AVAKIAN, R, ...

Transverse polarization of Lambda and (Lambda)over-bar hyperons in quasireal photoproduction (2007)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, AMMOSOV, VV, ANDRUS, A, ...

Nuclear Attenuation of high energy two-hadron system in the string model (2006)

Akopov, N., Grigoryan, L., Akopov, Z.

Nuclear attenuation of the two-hadron system is considered in the string model. The two-scale model and its improved version with two different choices of constituent formation time and sets of...

Double-hadron leptoproduction in the nuclear medium (2006)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, ANDRUS, A, ASCHENAUER, EC, ...

Longitudinal spin transfer to the Lambda hyperon in semiinclusive deep-inelastic scattering (2006)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z

The HERMES polarized hydrogen and deuterium gas target in the HERA electron storage ring (2005)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, ANDRUS, A, ASCHENAUER, EC, ...

Measurement of the tensor structure function b(1) of the deuteron (2005)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, AMMOSOV, VV, ANDRUS, A, ...

Subleading-twist effects in single-spin asymmetries in semi-inclusive deep-inelastic scattering on a longitudinally polarized hydrogen target (2005)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, ANDRUS, A, ASCHENAUER, EC, ...

Single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target (2005)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, ANDRUS, A, ASCHENAUER, EC, ...

Quark helicity distributions in the nucleon for up, down, and strange quarks from semi-inclusive deep-inelastic scattering (2005)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, AMMOSOV, VV, ANDRUS, A, ...

Search for an exotic S =-2, Q =-2 baryon resonance at a mass near 1862 MeV in quasireal photoproduction (2005)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, ANDRUS, A, ASCHENAUER, EC, ...

Application of the Two-Scale Model to the HERMES Data on Nuclear Attenuation (2004)

Akopov, N., Grigoryan, L., Akopov, Z.

The Two-Scale Model and its improved version were used to perform the fit to the HERMES data for $\nu$ (the virtual photon energy) and z (the fraction of $\nu$ carried by hadron) dependencies of...

Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering (2004)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Double-spin asymmetries of semiinclusive cross sections for the production of identified pions and kaons have been measured in deep inelastic scattering of polarized positrons on a polarized...

Hard exclusive electroproduction of π+π-pairs (2004)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Hard exclusive electroproduction of pi(+) pi(-) pairs off hydrogen and deuterium targets has been studied by the HERMES experiment at DESY Legendre moments (P-1) and (P-3) of the angular...

Evidence for a narrow |S|=1 baryon state at a mass of 1528 MeV in quasi-real photoproduction (2004)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Evidence for a narrow baryon state is found in quasi-real photoproduction on a deuterium target through the decay channel pK(S)(0) → ppi(+)pi(-). A peak is observed in the pK(S)(0) invariant mass...

Nuclear polarization of molecular hydrogen recombined on a non-metallic surface (2004)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, AMMOSOV, VV, ANDRUS, A, ...

Evidence for a narrow vertical bar S vertical bar=1 baryon state at a mass of 1528 MeV in quasi-real photoproduction (2004)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, AMMOSOV, VV, ANDRUS, A, ...

Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering (2004)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, AMMOSOV, VV, ANDRUS, A, ...

Hard exclusive electroproduction of pi(+)pi(-) pairs (2004)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, AMMOSOV, VV, ANDRUS, A, ...

Double-spin asymmetries in the cross section of rho /sup 0/ and phi production at intermediate energies (2003)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Double-spin asymmetries in the cross section of electroproduction of rho /sup 0/ and phi mesons on the proton and deuteron are measured at the HERMES experiment. The photoabsorption asymmetry in...

Measurement of single-spin azimuthal asymmetries in semi-inclusive electroproduction of pions and kaons on a longitudinally polarised deuterium target (2003)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Single-spin asymmetries have been measured for semi-inclusive electroproduction of pi /sup +/, pi /sup -/, pi /sup 0/ and K/sup +/ mesons in deep-inelastic scattering off a longitudinally polarised...

Evidence for quark-hadron duality in the proton spin asymmetry A1 (2003)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Aschenauer, E.C., ...

Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry A1. Longitudinally polarized positrons were...

Q2 dependence of nuclear transparency for exclusive rho0 production (2003)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Exclusive coherent and incoherent electroproduction of the rho(0) meson from H-1 and N-14 targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to...

The Time-of-Flight Technique for the HERMES Experiment (2003)

Airapetian, HERMES Collaboration: A., Akopov, N., Amarian, M., Avakian, H., Avetissian, A., Avetisyan, E., ...

This paper describes the use of the time-of-flight (TOF) technique as a particle identification method for the HERMES experiment. The time-of-flight is measured by two 1x4 m^2 scintillation...

Q2 dependence of nuclear transparency for exclusive rho0 production (2003)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Exclusive coherent and incoherent electroproduction of the rho(0) meson from H-1 and N-14 targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to...

Quark fragmentation to pi(+/-), pi(0), K-+/-, p and (p)over-bar in the nuclear environment (2003)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

The influence of the nuclear medium on lepto-production of hadrons was studied in the HERMES experiment at DESY in semi- inclusive deep-inelastic scattering of 27.6 GeV positrons off deuterium,...

The Q(2)-dependence of the generalised Gerasimov-Drell-Hearn integral for the deuteron, proton and neutron (2003)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Aschenauer, E.C., ...

The Gerasimov-Drell-Hearn (GDH) sum rule connects the anomalous contribution to the magnetic moment of the target nucleus with an energy-weighted integral of the difference of the helicity- dependent...

Quark fragmentation to pi(+/-), pi(0), K-+/-, p and (p)over-bar in the nuclear environment (2003)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, AMMOSOV, VV, ANDRUS, A, ...

Nuclear effects on R = sigma(L)/sigma(T) in deep-inelastic scattering (vol 475, pg 386, 2000) (2003)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z

Measurement of single-spin azimuthal asymmetries in semi-inclusive electroproduction of pions and kaons on a longitudinally polarised deuterium target (2003)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, AMMOSOV, VV, ANDRUS, A, ...

The Q(2)-dependence of the generalised Gerasimov-Drell-Hearn integral for the deuteron, proton and neutron (2003)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z, AMARIAN, M, AMMOSOV, VV, ASCHENAUER, EC, ...

Evidence for quark-hadron duality in the proton spin asymmetry A(1) (2003)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z

Q(2) dependence of nuclear transparency for exclusive rho(0) production (2003)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z

Double-spin asymmetries in the cross section of rho(0) and phi production at intermediate energies (2003)

AIRAPETIAN, A, AKOPOV, N, AKOPOV, Z

Single-spin azimuthal asymmetry in exclusive electroproduction of pi /sup +/ mesons (2002)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Aschenauer, E.C., Avakian, H., ...

A single-spin asymmetry in the distribution of exclusively produced pi /sup +/ mesons azimuthally around the virtual photon direction relative to the lepton scattering plane has been measured for the...

The HERMES dual-radiator ring imaging Cherenkov detector (2002)

Akopov, N., Aschenauer, E.C., Bailey, K., Bernreuther, S., Bianchi, N., Capitani, G.P., ...

The construction and use of a dual radiator Ring Imaging Cherenkov (RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasises measurements of...

The HERMES dual-radiator ring imaging Cherenkov detector. (2002)

AKOPOV, N, ASCHENAUER, EC, BAILEY, K, BERNREUTHER, K, BIANCHI, N, CAPITANI, GP, ...

Single-spin azimuthal asymmetry in exclusive electroproduction of pi(+) mesons (2002)

Airapetian, A, Akopov, N, Akopov, Z, Hommez, B, Ryckbosch, Dirk, Tytgat, Michael, ...

A single-spin asymmetry in the distribution of exclusively produced pi(+) mesons azimuthally around the virtual photon direction relative to the lepton scattering plane has been measured for the...

Measurement of longitudinal spin transfer to Lambda hyperons in deep-inelastic lepton scattering (2001)

Airapetian, A., Akopov, N., Amarian, M., Aschenauer, E.C., Avakian, H., Avakian, R., ...

Spin transfer in deep-inelastic Lambda electroproduction has been studied with the HERMES detector using the 27.6 GeV polarized positron beam in the DESY HERA storage ring. For an average fractional...

Single-spin azimuthal asymmetries in electroproduction of neutral pions in semi-inclusive deep-inelastic scattering (2001)

Airapetian, A, Akopov, N., Akopov, Z., Amarian, M, Aschenauer, E.C., Avakian, H., ...

A single-spin asymmetry in the azimuthal distribution of neutral pions relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off...

Double-spin asymmetry in the cross section for exclusive rho0 production in lepton-proton scattering (2001)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Arrington, J., Aschenauer, E.C., ...

Evidence for a positive longitudinal double-spin asymmetry (A/sub 1//sup rho /)=0.24+or-0.11/sub stat/+or-0.02/sub syst/ in the cross section for exclusive diffractive rho /sup 0/(770) vector-meson...

The HERMES Dual-Radiator Ring Imaging Cerenkov Detector (2001)

Akopov, N.

The construction and use of a dual radiator Ring Imaging Cerenkov(RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasizes measurements of...

Single-spin azimuthal asymmetries in electroproduction of neutral pions in semi-inclusive deep-inelastic scattering (2001)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Aschenauer, E.C., Avakian, H., ...

Hadron formation in deep-inelastic positron scattering in a nuclear environment (2001)

Airapetian, A., Akopov, N., Akopov, Z., Akushevich, I., Amarian, T., Arrington, J., ...

The influence of the nuclear medium on the production of charged hadrons in semi-inclusive deep-inelastic scattering has been studied by the HERMES experiment at DESY using a 27.5 GeV positron beam....

Measurement of the beam-spin azimuthal asymmetry associated with deeply-virtual compton scattering (2001)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Aschenauer, E.C., Avakian, H., ...

The beam spin asymmetry in hard electroproduction of photons was measured in the missing-mass (Mx) range upto 7 GeV. A nonzero asymmetry was observed in the exclusive domain for Mx [less-than or...

Multiplicity of charged and neutral pions in deep-inelastic scattering of 27.5 GeV positrons on hydrogen (2001)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Arrington, J., Aschenauer, E.C., ...

Measurements of the individual multiplicities of pi /sup +/, pi /sup -/ and pi /sup 0/ produced in the deep-inelastic scattering of 27.5 GeV positrons on hydrogen are presented. The average charged...

Measurement of the Beam-Spin Azimuthal Asymmetry Associated with Deeply-Virtual Compton Scattering (2001)

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Aschenauer, E. C.

Exclusive Leptoproduction of (2000)

Mesons From Hydrogen, A. Airapetian, N. Akopov, I. Akushevich, M. Amarian, J. Arrington, ...

. Measurements of the cross section for exclusive virtual-photoproduction of ae 0 mesons from hydrogen are reported. The data were collected by the HERMES experiment using 27.5 GeV positrons incident...

Measurement of Angular Distributions and (2000)

In Diractive Electroproduction, A. Airapetian, N. Akopov, M. Amarian, H. Avakian

. Production and decay angular distributions were extracted from measurements of exclusive electroproduction of the # 0 (770) meson over a range in the virtual photon negative four-momentum squared...

Observation of a coherence length effect in exclusive ρ(0) electroproduction (1999)

Ackerstaff, K., Airapetian, A., Akopov, N., Akushevich, I., Amarian, M., Aschenauer, E. C., ...

Exclusive incoherent electroproduction of the ρ0(770) meson from 1H, 2H, 3He, and 14N targets has been studied by the HERMES experiment at squared four-momentum transfer Q^2>0.4 GeV^2 and positron...

Beam-induced nuclear depolarization in a gaseous polarized-hydrogen target (1999)

Ackerstaff, K., Airapetian, A., Akopov, N., Amarian, M., Aschenauer, E. C., Avakian, H., ...

Spin-polarized atomic hydrogen is used as a gaseous polarized-proton target in high-energy and nuclear-physics experiments operating with internal beams in storage rings. When such beams are intense...

Flavor asymmetry of the light quark sea from semi-inclusive deep-inelastic scattering (1998)

Ackerstaff, K., Airapetian, A., Akopov, N., Akushevich, I., Amarian, M., Ashenauer, E. C., ...

The flavor asymmetry of the light quark sea of the nucleon is determined in the kinematic range 0.02 < x < 0.3 and 1 < Q(2) < 10 GeV2 for the first time from semi-inclusive deep-inelastic scattering....

The HERMES Spectrometer (1998)

Ackerstaff Airapetian Akopov, K. Ackerstaff, A. Airapetian, N. Akopov, M. Amarian, V. Andreev, ...

The HERMES experiment is collecting data on inclusive and semi-inclusive deep inelastic scattering of polarised positrons from polarised targets of H, D, and 3 He. These data give information on the...

Double-spin asymmetries in the cross section of rho /sup 0/ and phi production at intermediate energies

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Double-spin asymmetries in the cross section of electroproduction of rho /sup 0/ and phi mesons on the proton and deuteron are measured at the HERMES experiment. The photoabsorption asymmetry in...

Double-spin asymmetry in the cross section for exclusive rho0 production in lepton-proton scattering

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Arrington, J., Aschenauer, E.C., ...

Evidence for a positive longitudinal double-spin asymmetry (A/sub 1//sup rho /)=0.24+or-0.11/sub stat/+or-0.02/sub syst/ in the cross section for exclusive diffractive rho /sup 0/(770) vector-meson...

Evidence for quark-hadron duality in the proton spin asymmetry A1

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Aschenauer, E.C., ...

Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry A1. Longitudinally polarized positrons were...

Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Double-spin asymmetries of semiinclusive cross sections for the production of identified pions and kaons have been measured in deep inelastic scattering of polarized positrons on a polarized...

Hadron formation in deep-inelastic positron scattering in a nuclear environment

Airapetian, A., Akopov, N., Akopov, Z., Akushevich, I., Amarian, T., Arrington, J., ...

The influence of the nuclear medium on the production of charged hadrons in semi-inclusive deep-inelastic scattering has been studied by the HERMES experiment at DESY using a 27.5 GeV positron beam....

Measurement of longitudinal spin transfer to Lambda hyperons in deep-inelastic lepton scattering

Airapetian, A., Akopov, N., Amarian, M., Aschenauer, E.C., Avakian, H., Avakian, R., ...

Spin transfer in deep-inelastic Lambda electroproduction has been studied with the HERMES detector using the 27.6 GeV polarized positron beam in the DESY HERA storage ring. For an average fractional...

Measurement of single-spin azimuthal asymmetries in semi-inclusive electroproduction of pions and kaons on a longitudinally polarised deuterium target

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Single-spin asymmetries have been measured for semi-inclusive electroproduction of pi /sup +/, pi /sup -/, pi /sup 0/ and K/sup +/ mesons in deep-inelastic scattering off a longitudinally polarised...

Measurement of the beam-spin azimuthal asymmetry associated with deeply-virtual compton scattering

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Aschenauer, E.C., Avakian, H., ...

The beam spin asymmetry in hard electroproduction of photons was measured in the missing-mass (Mx) range upto 7 GeV. A nonzero asymmetry was observed in the exclusive domain for Mx [less-than or...

Multiplicity of charged and neutral pions in deep-inelastic scattering of 27.5 GeV positrons on hydrogen

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Arrington, J., Aschenauer, E.C., ...

Measurements of the individual multiplicities of pi /sup +/, pi /sup -/ and pi /sup 0/ produced in the deep-inelastic scattering of 27.5 GeV positrons on hydrogen are presented. The average charged...

Q2 dependence of nuclear transparency for exclusive rho0 production

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Exclusive coherent and incoherent electroproduction of the rho(0) meson from H-1 and N-14 targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to...

Q2 dependence of nuclear transparency for exclusive rho0 production

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Exclusive coherent and incoherent electroproduction of the rho(0) meson from H-1 and N-14 targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to...

Quark fragmentation to pi(+/-), pi(0), K-+/-, p and (p)over-bar in the nuclear environment

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

The influence of the nuclear medium on lepto-production of hadrons was studied in the HERMES experiment at DESY in semi- inclusive deep-inelastic scattering of 27.6 GeV positrons off deuterium,...

Single-spin azimuthal asymmetry in exclusive electroproduction of pi /sup +/ mesons

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Aschenauer, E.C., Avakian, H., ...

A single-spin asymmetry in the distribution of exclusively produced pi /sup +/ mesons azimuthally around the virtual photon direction relative to the lepton scattering plane has been measured for the...

Single-spin azimuthal asymmetries in electroproduction of neutral pions in semi-inclusive deep-inelastic scattering

Airapetian, A, Akopov, N., Akopov, Z., Amarian, M, Aschenauer, E. C., Avakian, H., ...

A single-spin asymmetry in the azimuthal distribution of neutral pions relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off...

The Q(2)-dependence of the generalised Gerasimov-Drell-Hearn integral for the deuteron, proton and neutron

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Aschenauer, E.C., ...

The Gerasimov-Drell-Hearn (GDH) sum rule connects the anomalous contribution to the magnetic moment of the target nucleus with an energy-weighted integral of the difference of the helicity- dependent...

The HERMES dual-radiator ring imaging Cherenkov detector

Akopov, N., Aschenauer, E.C., Bailey, K., Bernreuther, S., Bianchi, N., Capitani, G.P., ...

The construction and use of a dual radiator Ring Imaging Cherenkov (RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasises measurements of...

Hard exclusive electroproduction of π+π-pairs

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Hard exclusive electroproduction of pi(+) pi(-) pairs off hydrogen and deuterium targets has been studied by the HERMES experiment at DESY Legendre moments (P-1) and (P-3) of the angular...

Evidence for a narrow |S|=1 baryon state at a mass of 1528 MeV in quasi-real photoproduction

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Evidence for a narrow baryon state is found in quasi-real photoproduction on a deuterium target through the decay channel pK(S)(0) → ppi(+)pi(-). A peak is observed in the pK(S)(0) invariant mass...

Double-spin asymmetries in the cross section of rho /sup 0/ and phi production at intermediate energies

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Double-spin asymmetries in the cross section of electroproduction of rho /sup 0/ and phi mesons on the proton and deuteron are measured at the HERMES experiment. The photoabsorption asymmetry in...

Double-spin asymmetry in the cross section for exclusive rho0 production in lepton-proton scattering

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Arrington, J., Aschenauer, E.C., ...

Evidence for a positive longitudinal double-spin asymmetry (A/sub 1//sup rho /)=0.24+or-0.11/sub stat/+or-0.02/sub syst/ in the cross section for exclusive diffractive rho /sup 0/(770) vector-meson...

Evidence for quark-hadron duality in the proton spin asymmetry A1

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Aschenauer, E.C., ...

Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry A1. Longitudinally polarized positrons were...

Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Double-spin asymmetries of semiinclusive cross sections for the production of identified pions and kaons have been measured in deep inelastic scattering of polarized positrons on a polarized...

Hadron formation in deep-inelastic positron scattering in a nuclear environment

Airapetian, A., Akopov, N., Akopov, Z., Akushevich, I., Amarian, T., Arrington, J., ...

The influence of the nuclear medium on the production of charged hadrons in semi-inclusive deep-inelastic scattering has been studied by the HERMES experiment at DESY using a 27.5 GeV positron beam....

Measurement of longitudinal spin transfer to Lambda hyperons in deep-inelastic lepton scattering

Airapetian, A., Akopov, N., Amarian, M., Aschenauer, E.C., Avakian, H., Avakian, R., ...

Spin transfer in deep-inelastic Lambda electroproduction has been studied with the HERMES detector using the 27.6 GeV polarized positron beam in the DESY HERA storage ring. For an average fractional...

Measurement of single-spin azimuthal asymmetries in semi-inclusive electroproduction of pions and kaons on a longitudinally polarised deuterium target

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Single-spin asymmetries have been measured for semi-inclusive electroproduction of pi /sup +/, pi /sup -/, pi /sup 0/ and K/sup +/ mesons in deep-inelastic scattering off a longitudinally polarised...

Measurement of the beam-spin azimuthal asymmetry associated with deeply-virtual compton scattering

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Aschenauer, E.C., Avakian, H., ...

The beam spin asymmetry in hard electroproduction of photons was measured in the missing-mass (Mx) range upto 7 GeV. A nonzero asymmetry was observed in the exclusive domain for Mx [less-than or...

Multiplicity of charged and neutral pions in deep-inelastic scattering of 27.5 GeV positrons on hydrogen

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Arrington, J., Aschenauer, E.C., ...

Measurements of the individual multiplicities of pi /sup +/, pi /sup -/ and pi /sup 0/ produced in the deep-inelastic scattering of 27.5 GeV positrons on hydrogen are presented. The average charged...

Q2 dependence of nuclear transparency for exclusive rho0 production

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Exclusive coherent and incoherent electroproduction of the rho(0) meson from H-1 and N-14 targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to...

Q2 dependence of nuclear transparency for exclusive rho0 production

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Exclusive coherent and incoherent electroproduction of the rho(0) meson from H-1 and N-14 targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to...

Quark fragmentation to pi(+/-), pi(0), K-+/-, p and (p)over-bar in the nuclear environment

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

The influence of the nuclear medium on lepto-production of hadrons was studied in the HERMES experiment at DESY in semi- inclusive deep-inelastic scattering of 27.6 GeV positrons off deuterium,...

Single-spin azimuthal asymmetry in exclusive electroproduction of pi /sup +/ mesons

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Aschenauer, E.C., Avakian, H., ...

A single-spin asymmetry in the distribution of exclusively produced pi /sup +/ mesons azimuthally around the virtual photon direction relative to the lepton scattering plane has been measured for the...

Single-spin azimuthal asymmetries in electroproduction of neutral pions in semi-inclusive deep-inelastic scattering

Airapetian, A, Akopov, N., Akopov, Z., Amarian, M, Aschenauer, E. C., Avakian, H., ...

A single-spin asymmetry in the azimuthal distribution of neutral pions relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off...

The Q(2)-dependence of the generalised Gerasimov-Drell-Hearn integral for the deuteron, proton and neutron

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Aschenauer, E.C., ...

The Gerasimov-Drell-Hearn (GDH) sum rule connects the anomalous contribution to the magnetic moment of the target nucleus with an energy-weighted integral of the difference of the helicity- dependent...

The HERMES dual-radiator ring imaging Cherenkov detector

Akopov, N., Aschenauer, E.C., Bailey, K., Bernreuther, S., Bianchi, N., Capitani, G.P., ...

The construction and use of a dual radiator Ring Imaging Cherenkov (RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasises measurements of...

Hard exclusive electroproduction of π+π-pairs

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Hard exclusive electroproduction of pi(+) pi(-) pairs off hydrogen and deuterium targets has been studied by the HERMES experiment at DESY Legendre moments (P-1) and (P-3) of the angular...

Evidence for a narrow |S|=1 baryon state at a mass of 1528 MeV in quasi-real photoproduction

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Andrus, A., ...

Evidence for a narrow baryon state is found in quasi-real photoproduction on a deuterium target through the decay channel pK(S)(0) → ppi(+)pi(-). A peak is observed in the pK(S)(0) invariant mass...