S.A. Bunyatov

PERFORMANCE OF THE NOMAD TRANSITION RADIATION DETECTOR

Abstract The NOMAD experiment includes a transition radiation detector that provides a 103 pion rejection factor, for a 90% electron identification efficiency. Such a rejection factor is required in the search for νμ→ντ oscillations in the τ electron decay channel and in the search for νμ→νe oscillations. Algorithms used for the electron–pion discrimination and results obtained on the data are described.

Large-angle production of charged pions with 3-12.9 GeV/c incident protons on nuclear targets

M.G. Catanesi, E. Radicioni, R. Edgecock, M. Ellis, ∗ F.J.P. Soler, C. Gößling, S. Bunyatov, A. Krasnoperov, B. Popov, † V. Serdiouk, V. Tereschenko, E. Di Capua, G. Vidal–Sitjes, ‡ A. Artamonov, § S. Giani, S. Gilardoni, P. Gorbunov, § A. Grant, A. Grossheim, ¶ A. Ivanchenko, ∗∗ V. Ivanchenko, †† A. Kayis-Topaksu, ‡‡ J. Panman, I. Papadopoulos, E. Tcherniaev, I. Tsukerman, § R. Veenhof, C. Wiebusch, §§ P. Zucchelli, ¶¶ A. Blondel, S. Borghi, M.C. Morone, ∗∗∗ G. Prior, † † † R. Schroeter, C. Meurer, U. Gastaldi, G. B. Mills, ‡ ‡ ‡ J.S. Graulich, §§§ G. Grégoire, M. Bonesini, ¶¶¶ F. Ferri, M. Kirsanov, A. Bagulya, V. Grichine, N. Polukhina, V. Palladino, L. Coney, ‡ ‡ ‡ D. Schmitz, ‡ ‡ ‡ G. Barr, A. De Santo, F. Bobisut, D. Gibin, A. Guglielmi, M. Mezzetto, J. Dumarchez, U. Dore, D. Orestano, F. Pastore, A. Tonazzo, L. Tortora, C. Booth, L. Howlett, G. Skoro, M. Bogomilov, M. Chizhov, D. Kolev, R. Tsenov, S. Piperov, P. Temnikov, M. Apollonio, P. Chimenti, G. Giannini, J. Burguet–Castell, A. Cervera–Villanueva, J.J. Gómez–Cadenas, J. Mart́ın–Albo, P. Novella, M. Sorel, and A. Tornero (HARP Collaboration)

Limits on neutral light scalar and pseudoscalar particles in a proton beam dump experiment

A search has been performed for weakly interacting neutral light scalar and pseudoscalar particles in a proton beam dump experiment. No positive signal is observed. Limits on the mass and life-time of these particles are set in the frame of the Standard Model and its minimal supersymmetric extension. The Higgs particle of theSU2L×U1 Standard Theory is excluded for masses in the range 1 MeV<mH<80 MeV at 95%CL. Limits on the Peccei-Quinn like axions are derived.

Measurement of the production cross-sections of pi(+/-) in p-C and pi(+/-)-C interactions at 12 GeV/c

The results of the measurements of the double-differential production cross-sections of pions, dσ/dpdΩ, in p-C and π-C interactions using the forward spectrometer of the HARP experiment are presented. The incident particles are 12 GeV/c protons and charged pions directed onto a carbon target with a thickness of 5% of a nuclear interaction length. For p-C interactions the analysis is performed using 100 035 reconstructed secondary tracks, while the corresponding numbers of tracks for π-C and π-C analyses are 106 534 and 10 122 respectively. Cross-section results are presented in the kinematic range 0.5 GeV/c ≤ pπ < 8 GeV/c and 30 mrad ≤ θπ < 240 mrad in the laboratory frame. The measured cross-sections have a direct impact on the precise calculation of atmospheric neutrino fluxes and on the improved reliability of extensive air shower simulations by reducing the uncertainties of hadronic interaction models in the low energy range. HARP collaboration M.G. Catanesi, E. Radicioni Università degli Studi e Sezione INFN, Bari, Italy R. Edgecock, M. Ellis, S. Robbins, F.J.P. Soler Rutherford Appleton Laboratory, Chilton, Didcot, UK C. Gößling Institut für Physik, Universität Dortmund, Germany S. Bunyatov, A. Krasnoperov, B. Popov, V. Tereshchenko Joint Institute for Nuclear Research, JINR Dubna, Russia E. Di Capua, G. Vidal–Sitjes Università degli Studi e Sezione INFN, Ferrara, Italy A. Artamonov, S. Giani, S. Gilardoni, P. Gorbunov, A. Grant, A. Grossheim, P. Gruber, V. Ivanchenko, A. Kayis-Topaksu, J. Panman, I. Papadopoulos, E. Tcherniaev, I. Tsukerman, R. Veenhof, C. Wiebusch, P. Zucchelli CERN, Geneva, Switzerland A. Blondel, S. Borghi, M. Campanelli, M.C. Morone, G. Prior, R. Schroeter Section de Physique, Université de Genève, Switzerland R. Engel, C. Meurer Forschungszentrum Karlsruhe, Institut für Kernphysik, Karlsruhe, Germany I. Kato University of Kyoto, Japan U. Gastaldi Laboratori Nazionali di Legnaro dell’ INFN, Legnaro, Italy G. B. Mills Los Alamos National Laboratory, Los Alamos, USA J.S. Graulich, G. Grégoire Institut de Physique Nucléaire, UCL, Louvain-la-Neuve, Belgium M. Bonesini, F. Ferri Università degli Studi e Sezione INFN, Milano, Italy M. Kirsanov Institute for Nuclear Research, Moscow, Russia A. Bagulya, V. Grichine, N. Polukhina P. N. Lebedev Institute of Physics (FIAN), Russian Academy of Sciences, Moscow, Russia V. Palladino Università “Federico II” e Sezione INFN, Napoli, Italy L. Coney, D. Schmitz Columbia University, New York, USA G. Barr, A. De Santo, C. Pattison, K. Zuber Nuclear and Astrophysics Laboratory, University of Oxford, UK F. Bobisut, D. Gibin, A. Guglielmi, M. Mezzetto Università degli Studi e Sezione INFN, Padova, Italy J. Dumarchez, F. Vannucci LPNHE, Universités de Paris VI et VII, Paris, France U. Dore Università “La Sapienza” e Sezione INFN Roma I, Roma, Italy D. Orestano, F. Pastore, A. Tonazzo, L. Tortora Università degli Studi e Sezione INFN Roma III, Roma, Italy C. Booth, L. Howlett Dept. of Physics, University of Sheffield, UK M. Bogomilov, M. Chizhov, D. Kolev, R. Tsenov Faculty of Physics, St. Kliment Ohridski University, Sofia, Bulgaria S. Piperov, P. Temnikov Institute for Nuclear Research and Nuclear Energy, Academy of Sciences, Sofia, Bulgaria M. Apollonio, P. Chimenti, G. Giannini, G. Santin Università degli Studi e Sezione INFN, Trieste, Italy J. Burguet–Castell, A. Cervera–Villanueva, J.J. Gómez–Cadenas, J. Mart́ın–Albo, P. Novella, M. Sorel Instituto de F́ısica Corpuscular, IFIC, CSIC and Universidad de Valencia, Spain Now at FNAL, Batavia, Illinois, USA. Jointly appointed by Nuclear and Astrophysics Laboratory, University of Oxford, UK. Now at Codian Ltd., Langley, Slough, UK. Now at University of Glasgow, UK. Also supported by LPNHE, Universités de Paris VI et VII, Paris, France. Now at Imperial College, University of London, UK. ITEP, Moscow, Russian Federation. Permanently at Instituto de F́ısica de Cantabria, Univ. de Cantabria, Santander, Spain. Now at SpinX Technologies, Geneva, Switzerland. Now at TRIUMF, Vancouver, Canada. Now at University of St. Gallen, Switzerland. On leave of absence from Ecoanalitica, Moscow State University, Moscow, Russia. Now at Çukurova University, Adana, Turkey. Now at III Phys. Inst. B, RWTH Aachen, Aachen, Germany. On leave of absence from INFN, Sezione di Ferrara, Italy. Now at CERN, Geneva, Switzerland. Now at Univerity of Rome Tor Vergata, Italy. Now at Lawrence Berkeley National Laboratory, Berkeley, California, USA. K2K Collaboration. MiniBooNE Collaboration. Now at Section de Physique, Université de Genève, Switzerland, Switzerland. Now at Royal Holloway, University of London, UK. Now at University of Sussex, Brighton, UK. Now at ESA/ESTEC, Noordwijk, The Netherlands.

Search for heavy neutrinos at the IHEP-JINR neutrino detector

Abstract Data from a proton beam-dump experiment at the 70 GeV Serpukhov accelerator were analysed to search for heavy neutrino decays ν H → e + e − ν e at the IHEP-JINR Neutrino Detector. No signal over background was found. The upper limits on the elements if a mixing matrix | U eH | 2 in the mass range 5 m νH U eH || U μH | in the mass range 3 m νH

Antiproton Annihilation on Ag/Br Nuclei

The charged-prong multiplicity distribution of (, Ag/Br) annihilation events has been measured in photographic emulsion at incoming momenta of 500, 400, 300 MeV/c and at rest. In the light of INC model predictions, the results show that the low-multiplicity events are produced mainly by nuclear surface annihilations and the higher multiplicity events can be interpreted as annihilations occurred in deep nuclear matter.

Large-angle production of charged pions with incident pion beams on nuclear targets

We gratefully acknowledge the help and support of the PS beam staff and of the numerous technical collaborators who contributed to the detector design, construction, commissioning and operation. In particular, we would like to thank G. Barichello, R. Brocard, K. Burin, V. Carassiti, F. Chignoli, D. Conventi, G. Decreuse, M. Delattre, C. Detraz, A. Domeniconi, M. Dwuznik, F. Evangelisti, B. Friend, A. Iaciofano, I. Krasin, D. Lacroix, J.-C. Legrand, M. Lobello, M. Lollo, J. Loquet, F. Marinilli, J. Mulon, L. Musa, R. Nicholson, A. Pepato, P. Petev, X. Pons, I. Rusinov, M. Scandurra, E. Usenko, and R. van der Vlugt, for their support in the construction of the detector. The collaboration acknowledges the major contributions and advice of M. Baldo-Ceolin, L. Linssen, M.T. Muciaccia and A. Pullia during the construction of the experiment. The collaboration is indebted to V. Ableev, P. Arce, F. Bergsma, P. Binko, E. Boter, C. Buttar, M. Calvi, M. Campanelli, C. Cavion, A. Chukanov, A. De Min, M. Doucet, D. Dullmann, R. Engel, V. Ermilova, W. Flegel, P. Gruber, Y. Hayato, P. Hodgson, A. Ichikawa, I. Kato, O. Klimov, T. Kobayashi, D. Kustov, M. Laveder, M. Mass, H. Meinhard, T. Nakaya, K. Nishikawa, M. Paganoni, F. Paleari, M. Pasquali, J. Pasternak, C. Pattison, M. Placentino, S. Robbins, G. Santin, V. Serdiouk, S. Simone, A. Tornero, S. Troquereau, S. Ueda, A. Valassi, F. Vannucci and K. Zuber for their contributions to the experiment and to P. Dini for help in MC production. We acknowledge the contributions of V. Ammosov, G. Chelkov, D. Dedovich, F. Dydak, M. Gostkin, A. Guskov, D. Khartchenko, V. Koreshev, Z. Kroumchtein, I. Nefedov, A. Semak, J. Wotschack, V. Zaets and A. Zhemchugov to the work described in this paper. The experiment was made possible by grants from the Institut Interuniversitaire des Sciences Nucleaires and the Interuniversitair Instituut voor Kernwetenschappen (Belgium), Ministerio de Educacion y Ciencia, Grant FPA2003-06921-c02-02 and Generalitat Valenciana, grant GV00-054-1, CERN (Geneva, Switzerland), the German Bundesministerium fur Bildung und Forschung (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), INR RAS (Moscow), the Russian Foundation for Basic Research (grant 08-02-00018) and the Particle Physics and Astronomy Research Council (UK). We gratefully acknowledge their support. This work was supported in part by the Swiss National Science Foundation and the Swiss Agency for Development and Cooperation in the framework of the programme SCOPES - Scientific co-operation between Eastern Europe and Switzerland.

Forward production of charged pions with incident protons on nuclear targets at the CERN Proton Synchrotron

Measurements of the double-differential π production cross-section in the range of momentum 0.5 GeV/c ≤ p ≤ 8.0 GeV/c and angle 0.025 rad ≤ θ ≤ 0.25 rad in collisions of protons on beryllium, carbon, nitrogen, oxygen, aluminium, copper, tin, tantalum and lead are presented. The data were taken with the large acceptance HARP detector in the T9 beam line of the CERN PS. Incident particles were identified by an elaborate system of beam detectors. Thin targets of 5% of a nuclear interaction length were used. The tracking and identification of the produced particles were performed using the forward system of the HARP experiment. Results are obtained for the double-differential cross-sections dσ/dpdΩ mainly at four incident proton beam momenta (3 GeV/c, 5 GeV/c, 8 GeV/c and 12 GeV/c). Measurements are compared with the GEANT4 and MARS Monte Carlo generators. A global parametrization is provided as an approximation of all the collected datasets which can serve as a tool for quick yields estimates.

Annihilation of Antiprotons at Rest in 3He and 4He

Abstract At LEAR of CERN the annihilation of antiprotons, stopping in 3 He and 4 He filling a self-shunted streamer chamber in a magnetic field, has been studied. The charged-particle multiplicities have been measured and the relative probabilities of π − production in p 3 He and p 4 He annihilation events have been obtained. The ratio between the p annihilation probability on the neutron and the proton for 3 He and 4 He has been deduced to be about half the value obtained for 2 H in bubble chamber experiments. The analysis of the results shows that this difference cannot be due only to the pion final-state interaction or to the shadow effect of the nucleons of the nuclei. The probability of p annihilation at rest on a proton bound in the nucleus results to be twice as high as that on a bound neutron, showing the dominance of annihilation in the I = 0 isospin states.

Absolute momentum calibration of the HARP TPC

In the HARP experiment the large-angle spectrometer is using a cylindrical TPC as main tracking and particle identification detector. The momentum scale of reconstructed tracks in the TPC is the most important systematic error for the majority of kinematic bins used for the HARP measurements of the double-differential production cross-section of charged pions in proton interactions on nuclear targets at large angle. The HARP TPC operated with a number of hardware shortfalls and operational mistakes. Thus it was important to control and characterize its momentum calibration. While it was not possible to enter a direct particle beam into the sensitive volume of the TPC to calibrate the detector, a set of physical processes and detector properties were exploited to achieve a precise calibration of the apparatus. In the following we recall the main issues concerning the momentum measurement in the HARP TPC, and describe the crosschecks made to validate the momentum scale. As a conclusion, this analysis demonstrates that the measurement of momentum is correct within the published precision of 3%.