WorldWideScience

Sample records for antineutrons

  1. Antineutron physics

    CERN Document Server

    Bressani, Tullio

    2003-01-01

    Antineutrons ($\\overline{n}$'s) have been used only in the last few years as projectiles for nuclear and particle physics experiments, mainly in the low momentum region. The reason is that, in spite of some undoubted advantages (absence of Coulomb corrections, pure I=1 state for the ($\\overline{n}p$) system), the difficulties in obtaining beams of $\\overline{n}$'s of suitable intensity and energy definition were overwhelming. The setting-up of suitable beams at BNL and mainly at CERN LEAR (with momentum lower than 400 MeV/c) allowed a first round of interesting experiments. In this review a summary of the most important experimental issues obtained in this field will be presented. They range from studies on the antineutron annihilation dynamics, intended to shed light on the mechanisms responsible for the particles production as well as for the possible formation of quasinuclear nucleon-antinucleon bound states, to meson spectroscopy researches, aiming to identify the existence of new, possibly exotic, resona...

  2. Neutron-Antineutron Oscillations: Theoretical Status and Experimental Prospects

    CERN Document Server

    Phillips, D G; Babu, K; Banerjee, S; Baxter, D V; Berezhiani, Z; Bergevin, M; Bhattacharya, S; Brooijmans, G; Castellanos, L; Chen, M-C; Coppola, C E; Cowsik, R; Crabtree, J A; Das, P; Dees, E B; Dolgov, A; Ferguson, P D; Frost, M; Gabriel, T; Gal, A; Gallmeier, F; Ganezer, K; Golubeva, E; Greene, G; Hartfiel, B; Hawari, A; Heilbronn, L; Johnson, C; Kamyshkov, Y; Kerbikov, B; Kitaguchi, M; Kopeliovich, B Z; Kopeliovich, V B; Kuzmin, V A; Liu, C-Y; McGaughey, P; Mocko, M; Mohapatra, R; Mokhov, N; Muhrer, G; Mumm, H P; Okun, L; Pattie, R W; Quigg, C; Ramberg, E; Ray, A; Roy, A; Ruggles, A; Sarkar, U; Saunders, A; Serebrov, A P; Shimizu, H M; Shrock, R; Sikdar, A K; Sjue, S; Striganov, S; Townsend, L W; Tschirhart, R; Vainshtein, A; Van Kooten, R; Wang, Z; Young, A R

    2014-01-01

    This paper summarizes the relevant theoretical developments, outlines some ideas to improve experimental searches for free neutron-antineutron oscillations, and suggests avenues for future improvement in the experimental sensitivity.

  3. Study of Antineutron Production at LEAR

    CERN Multimedia

    2002-01-01

    The aim of this experiment is the study of antineutron ($\\bar{n}$) production at LEAR as a first step for the investigation of $\\bar{n}$-p $\\bar{n}$-n physics. A good method of producing high-quality $\\bar{n}$ beams is that of using the charge-exchange (CEX) reaction @*p~@A~$\\bar{n}$n on an external LH^2 target. The production of $\\bar{n}$ at 0|0 (see figure) may be most useful for some experiments, the production at different angles with the simultaneous detection of the associated neutron (tagged beam) most powerful for other measurements.\\\\ \\\\ The $\\bar{n}$ calorimeter consists of ten equal modules: each one is made of an iron slab, a scintillator wall and a plane of x-y streamer tubes, with a detecting area of @=~1~m|2. The $\\bar{n}$ calorimeter allows the determination of the time and the location of $\\bar{n}$ annihilations.

  4. Neutron-antineutron oscillations: Theoretical status and experimental prospects

    Science.gov (United States)

    Phillips, D. G.; Snow, W. M.; Babu, K.; Banerjee, S.; Baxter, D. V.; Berezhiani, Z.; Bergevin, M.; Bhattacharya, S.; Brooijmans, G.; Castellanos, L.; Chen, M.-C.; Coppola, C. E.; Cowsik, R.; Crabtree, J. A.; Das, P.; Dees, E. B.; Dolgov, A.; Ferguson, P. D.; Frost, M.; Gabriel, T.; Gal, A.; Gallmeier, F.; Ganezer, K.; Golubeva, E.; Greene, G.; Hartfiel, B.; Hawari, A.; Heilbronn, L.; Johnson, C.; Kamyshkov, Y.; Kerbikov, B.; Kitaguchi, M.; Kopeliovich, B. Z.; Kopeliovich, V. B.; Kuzmin, V. A.; Liu, C.-Y.; McGaughey, P.; Mocko, M.; Mohapatra, R.; Mokhov, N.; Muhrer, G.; Mumm, H. P.; Okun, L.; Pattie, R. W.; Quigg, C.; Ramberg, E.; Ray, A.; Roy, A.; Ruggles, A.; Sarkar, U.; Saunders, A.; Serebrov, A. P.; Shimizu, H. M.; Shrock, R.; Sikdar, A. K.; Sjue, S.; Striganov, S.; Townsend, L. W.; Tschirhart, R.; Vainshtein, A.; Van Kooten, R.; Wang, Z.; Young, A. R.

    2016-02-01

    The observation of neutrons turning into antineutrons would constitute a discovery of fundamental importance for particle physics and cosmology. Observing the n- n ¯ transition would show that baryon number (B) is violated by two units and that matter containing neutrons is unstable. It would provide a clue to how the matter in our universe might have evolved from the B = 0 early universe. If seen at rates observable in foreseeable next-generation experiments, it might well help us understand the observed baryon asymmetry of the universe. A demonstration of the violation of B- L by 2 units would have a profound impact on our understanding of phenomena beyond the Standard Model of particle physics. Slow neutrons have kinetic energies of a few meV. By exploiting new slow neutron sources and optics technology developed for materials research, an optimized search for oscillations using free neutrons from a slow neutron moderator could improve existing limits on the free oscillation probability by at least three orders of magnitude. Such an experiment would deliver a slow neutron beam through a magnetically-shielded vacuum chamber to a thin annihilation target surrounded by a low-background antineutron annihilation detector. Antineutron annihilation in a target downstream of a free neutron beam is such a spectacular experimental signature that an essentially background-free search is possible. An authentic positive signal can be extinguished by a very small change in the ambient magnetic field in such an experiment. It is also possible to improve the sensitivity of neutron oscillation searches in nuclei using large underground detectors built mainly to search for proton decay and detect neutrinos. This paper summarizes the relevant theoretical developments, outlines some ideas to improve experimental searches for free neutron oscillations, and suggests avenues both for theoretical investigation and for future improvement in the experimental sensitivity.

  5. Neutron-antineutron oscillations beyond the quasifree limit

    Science.gov (United States)

    Davis, E. David; Young, Albert R.

    2017-02-01

    Prompted by plans for a free neutron oscillation experiment at the European Spallation Source (ESS), we consider issues associated with the magnetic fields that must be present. To this end, we introduce a stochastic model of the residual magnetic field within the propagation region which draws on features of magnetic profiles measured during the last free oscillation experiment at the Institut Laue-Langevin (ILL). A perturbative analysis, which relates the antineutron probability to the power spectral density of the magnetic field sampled, suggests that deviations from the quasifree result will increase quadratically with the length l of the propagation region. However, with inclusion of averaging over representative spectra of neutron speeds, departures from the quasifree result are found to be approximately linear in l . As regards the large spikes in the magnetic field at, for example, joints in the magnetic shielding of the propagation region (despite compensating currents and magnetic idealization of the shield), we demonstrate that their effect scales as l /D3 /2, where D is the diameter of the cylindrical magnetic shielding, and identify conditions under which they can be neglected. We also establish that any large magnetic field encountered after the propagation region is exited will not diminish the probability for antineutron detection. For the range of values of l of most interest to the ESS experiment, it should suffice to improve on the level of magnetic suppression achieved at the ILL by a factor of 2.

  6. Neutron-antineutron oscillations beyond the quasi-free limit

    CERN Document Server

    Davis, E David

    2016-01-01

    Prompted by plans to conduct a new neutron oscillation experiment at the European Spallation Source (ESS), we consider issues associated with the magnetic field that must be present, some of which are potentially exacerbated by the significantly larger length $l$ contemplated for the neutron propagation region. To this end, we introduce a stochastic model of the residual magnetic field within the propagation region which draws on features of magnetic profiles measured during the last free neutron oscillation experiment [conducted at the Institut Laue-Langevin (ILL) in the 1990's]. We average over both fluctuations in the magnetic field sampled by neutrons, and representative spectra of neutron speeds. We find that deviations from the quasi-free result for the antineutron probability do not depend quadratically on $l$ (as a naive perturbative estimate would suggest) but increase only linearly with $l$. As regards the large spikes in the magnetic field which can be expected at, for example, joints in the magnet...

  7. Antineutron and antiproton nuclear interactions at very low energies

    Science.gov (United States)

    Friedman, E.

    2014-05-01

    Experimental annihilation cross sections of antineutrons and antiprotons at very low energies are compared. Features of Coulomb focusing are observed for pbar annihilation on protons. Direct comparisons for heavier targets are not straightforward due to lack of overlap between targets and energies of experimental results for pbar and nbar. Nevertheless, the annihilation cross sections for nbar on nuclei cannot be described by an optical potential that fits well all the available data on pbar interactions with nuclei. Comparisons made with the help of this potential reveal in the nbar data features similar to Coulomb focusing. Direct comparisons between nbar and pbar annihilations at very low energies would be possible when pbar cross sections are measured on the same targets and at the same energies as the available cross sections for nbar. Such measurements may be possible in the foreseeable future.

  8. Gauged B-L Number and Neutron--Antineutron Oscillation: Long-range Forces Mediated by Baryophotons

    CERN Document Server

    Addazi, Andrea; Kamyshkov, Yuri

    2016-01-01

    Transformation of neutron to antineutron is a small effect that has not yet been experimentally observed. %\\cite{Phillips:2014fgb}. In principle, it can occur with free neutrons in the vacuum or with bound neutrons inside the nuclear environment different for neutrons and antineutrons and for that reason in the latter case it is heavily suppressed. Free neutron transformation also can be suppressed if environmental vector field exists destinguishing neutron from antineutron. We consider here the case of a vector field coupled to $B-L$ charge of the particles ($B-L$ photons) and study a possibility of this to lead to the observable suppression of neutron to antineutron transformation. The suppression effect however can be removed by applying external magnetic field. If the neutron--antineutron oscillation will be discovered in free neutron oscillation experiments, this will imply limits on $B-L$ photon coupling constant and interaction radius few order of magnitudes stronger than present limits form the tests ...

  9. Neutron-antineutron transition as a test-bed for dynamical CPT violations

    Science.gov (United States)

    Addazi, Andrea

    2016-05-01

    We show a simple mechanism for a dynamical CPT violation in the neutron sector. In particular, we show a CPT-violating see-saw mechanism, generating a Majorana mass and a CPT-violating mass for the neutron. CPT-violating see-saw involves a sterile partner of the neutron, living in a hidden sector, in which CPT is spontaneously broken. In particular, neutrons (antineutrons) can communicate with the hidden sector through nonperturbative quantum gravity effects called exotic instantons. Exotic instantons dynamically break R-parity, generating one effective vertex between the neutron and its sterile partner. In this way, we show how a small CPT-violating mass term for the neutron is naturally generated. This model can be tested in the next generation of experiments in neutron-antineutron physics. This strongly motivates researches of CPT-violating effects in neutron-antineutron physics as a test-bed for dynamical CPT-violations in SM.

  10. A new high sensitivity search for neutron-antineutron oscillations at the ESS

    CERN Document Server

    Milstead, David

    2015-01-01

    A sensitive search for neutron-antineutron oscillations can provide a unique probe of some of the central questions in particle physics and cosmology: the energy scale and mechanism for baryon number violation, the origin of the baryon-antibaryon asymmetry of the universe, and the mechanism for neutrino mass generation. A remarkable opportunity has emerged to search for such oscillations with the construction of the European Spallation Source (ESS). A collaboration has been formed which has proposed a search at the ESS, which would provide a sensitivity to the oscillation probability which is three orders of magnitude greater than that achieved at an ILL experiment at which the present best limit on free neutron-antineutron oscillations was obtained.

  11. First Observation of the Decay D_s^+ to proton anti-neutron

    CERN Document Server

    Athar, S B; Yelton, J; Rubin, P; Eisenstein, B I; Karliner, I; Mehrabyan, S; Lowrey, N; Selen, M; White, E J; Wiss, J; Mitchell, R E; Shepherd, M R; Besson, D; Pedlar, T K; Cronin-Hennessy, D; Gao, K Y; Hietala, J; Kubota, Y; Klein, T; Lang, B W; Poling, R; Scott, A W; Zweber, P; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A G; Libby, J; Powell, A; Wilkinson, G; Ecklund, K M; Love, W; Savinov, V; López, A; Méndez, H; Ramírez, J; Ge, J Y; Miller, D H; Shipsey, I P J; Xin, B; Adams, G S; Anderson, M; Cummings, J P; Danko, I; Hu, D; Moziak, B; Napolitano, J; He, Q; Insler, J; Muramatsu, H; Park, C S; Thorndike, E H; Yang, F; Artuso, M; Blusk, S; Khalil, S; Li, J; Mountain, R; Nisar, S; Randrianarivony, K; Sultana, N; Skwarnicki, T; Stone, S; Wang, J C; Zhang, L M; Bonvicini, G; Cinabro, D; Dubrovin, M; Lincoln, A; Naik, P; Rademacker, J; Asner, D M; Edwards, K W; Reed, J; Briere, R A; Ferguson, T; Tatishvili, G; Vogel, H; Watkins, M E; Rosner, J L; Alexander, J P; Cassel, D G; Duboscq, J E; Ehrlich, R; Fields, L; Gibbons, L; Gray, R; Gray, S W; Hartill, D L; Heltsley, B K; Hertz, D; Hunt, J M; Kandaswamy, J; Kreinick, D L; Kuznetsov, V E; Ledoux, J; Mahlke-Krüger, H; Mohapatra, D; Onyisi, P U E; Patterson, J R; Peterson, D; Riley, D; Ryd, A; Sadoff, A J; Shi, X; Stroiney, S; Sun, W M; Wilksen, T

    2008-01-01

    Using e^+e^- -> D_s^*+ D_s^- data collected near the peak D_s production energy, E_cm=4170 MeV, with the CLEO-c detector, we present the first observation of the decay D_s^+ -> proton anti-neutron. We measure a branching fraction B(D_s^+ -> p anti-n = (1.30 +- 0.36 +0.12 -0.16) x 10^-3. This is the first observation of a charmed meson decaying into a baryon-antibaryon final state.

  12. Limiting Equivalence Principle Violation and Long-Range Baryonic Force from Neutron-Antineutron Oscillation

    CERN Document Server

    Babu, K S

    2016-01-01

    We point out that if the baryon number violating neutron-antineutron oscillation is discovered, it would impose strong limits on the departure from Einstein's equivalence principle at a level of one part in $10^{19}$. If this departure owes its origin to the existence of long-range forces coupled to baryon number $B$ (or $B-L$), it would imply very stringent constraints on the strength of gauge bosons coupling to baryon number current. For instance, if the force mediating baryon number has strength $\\alpha_B$ and its range is larger than a megaparsec, we find the limit to be $\\alpha_B \\leq 2\\times 10^{-57}$, which is much stronger than all other existing bounds. For smaller range for the force, we get slightly weaker, but still stringent bounds by considering the potential of the Earth and the Sun.

  13. Search for neutron-antineutron oscillations using multiprong events in Soudan 2

    Science.gov (United States)

    Chung, J.; Allison, W. W.; Alner, G. J.; Ayres, D. S.; Barrett, W. L.; Border, P. M.; Cobb, J. H.; Courant, H.; Demuth, D. M.; Fields, T. H.; Gallagher, H. R.; Goodman, M. C.; Gran, R.; Joffe-Minor, T.; Kafka, T.; Kasahara, S. M.; Litchfield, P. J.; Mann, W. A.; Marshak, M. L.; Milburn, R. H.; Miller, W. H.; Mualem, L.; Napier, A.; Oliver, W. P.; Pearce, G. F.; Peterson, E. A.; Petyt, D. A.; Ruddick, K.; Sanchez, M.; Schneps, J.; Sousa, A.; Speakman, B.; Thron, J. L.; Wakely, S. P.; West, N.

    2002-08-01

    We have searched for neutron-antineutron oscillations using the 5.56 fiducial kiloton-year exposure of the Soudan 2 iron tracking calorimeter. We require candidate nn¯ occurrences to have >=4 prongs (tracks and showers) and to have kinematics compatible with n¯N annihilation within a nucleus. We observe five candidate events, with an estimated background from atmospheric neutrino and cosmic ray induced events of 4.5+/-1.2 events. Previous experiments with smaller exposures observed no candidates, with estimated background rates similar to this experiment. We set a lifetime lower limit at 90% C.L. for the nn¯ oscillation time in iron: TA(Fe)>7.2×1031 yr. The corresponding lower limit for oscillation of free neutrons is τnn¯>1.3×108 sec.

  14. Sensitivity of experiment on search for neutron-antineutron oscillations on the projected ultracold neutron source at the WWR-M reactor

    Science.gov (United States)

    Serebrov, A. P.; Fomin, A. K.; Kamyshkov, Yu. A.

    2016-01-01

    An experiment on search for neutron-antineutron oscillations is proposed based on the storage of ultracold neutrons (UCNs) in a material trap. The main factors influencing sensitivity of the experiment are the trap size and the amount of UCNs trapped. A high-intensity UCN source will be created at the WWR-M reactor of Petersburg Nuclear Physics Institute, which must provide an UCN density two to three orders of magnitude higher than that in the existing sources. The results of simulations of the experiment for detecting neutron-antineutron oscillations with the new source show that the sensitivity can be increased by ~20-80 times compared to existing depending on the model of neutron reflection from walls.

  15. Antineutron-nucleus annihilation

    CERN Document Server

    Botta, E

    2001-01-01

    The n-nucleus annihilation process has been studied by the OBELIX experiment at the CERN Low Energy Antiproton Ring (LEAR) in the (50-400) MeV/c projectile momentum range on C, Al, Cu, Ag, Sn, and Pb nuclear targets. A systematic survey of the annihilation cross- section, sigma /sub alpha /(A, p/sub n/), has been performed, obtaining information on its dependence on the target mass number and on the incoming n momentum. For the first time the mass number dependence of the (inclusive) final state composition of the process has been analyzed. Production of the rho vector meson has also been examined. (13 refs).

  16. Characteristic Signal of Neutron-Antineutron Oscillation in Argon Nuclei at DUNE.

    Science.gov (United States)

    Barrow, Joshua; Kamyshkov, Yuri; Rybolt, Ben; Deep Underground Neutrino Experiment Collaboration

    2017-01-01

    Babu et al. have recently proposed a model of post-sphaleron baryogenesis following the electroweak phase transition. Their theory naturally gives rise to a plausible baryon abundance and a ΔB =2 six-quark operator which allows for the generation of nbar from n. Using n bound in Ar, DUNE currently plans to include n-nbar events in their nucleon decay searches. Using GENIE, modeling is underway on intranuclear interactions mimicking n-nbar annihilation in Ar nuclei. Eliminating atmospheric ν background from such events will be a challenge for liquid Ar TPCs at DUNE, so simulation work must be considered for ν interactions in Ar nuclei, which produce similar signals to n-nbar annihilation. Key to understanding possible experimental signals will be the integration of these two for a proper robust analysis, which will determine the viability of any detection of this process above background levels. Department of Energy-High Energy Physics.

  17. Damping and Decoherence in Neutron Oscillations

    CERN Document Server

    Kerbikov, B O; Kamyshkov, Y A; Varriano, L J

    2015-01-01

    An analysis is made of the role played by the gas environment in neutron-mirror-neutron and neutron-antineutron oscillations. In the first process the interaction with the ambient medium induces a refraction energy shift which plays the role of an extra magnetic field. In the second process antineutron annihilation in practice might lead to strong decoherence, which should be taken into account in experiments with free neutrons looking for the neutron to antineutron transformation.

  18. Baryon Number Violation

    CERN Document Server

    Babu, K S; Al-Binni, U; Banerjee, S; Baxter, D V; Berezhiani, Z; Bergevin, M; Bhattacharya, S; Brice, S; Brock, R; Burgess, T W; Castellanos, L; Chattopadhyay, S; Chen, M-C; Church, E; Coppola, C E; Cowen, D F; Cowsik, R; Crabtree, J A; Davoudiasl, H; Dermisek, R; Dolgov, A; Dutta, B; Dvali, G; Ferguson, P; Perez, P Fileviez; Gabriel, T; Gal, A; Gallmeier, F; Ganezer, K S; Gogoladze, I; Golubeva, E S; Graves, V B; Greene, G; Handler, T; Hartfiel, B; Hawari, A; Heilbronn, L; Hill, J; Jaffe, D; Johnson, C; Jung, C K; Kamyshkov, Y; Kerbikov, B; Kopeliovich, B Z; Kopeliovich, V B; Korsch, W; Lachenmaier, T; Langacker, P; Liu, C-Y; Marciano, W J; Mocko, M; Mohapatra, R N; Mokhov, N; Muhrer, G; Mumm, P; Nath, P; Obayashi, Y; Okun, L; Pati, J C; Pattie, R W; Phillips, D G; Quigg, C; Raaf, J L; Raby, S; Ramberg, E; Ray, A; Roy, A; Ruggles, A; Sarkar, U; Saunders, A; Serebrov, A; Shafi, Q; Shimizu, H; Shiozawa, M; Shrock, R; Sikdar, A K; Snow, W M; Soha, A; Spanier, S; Stavenga, G C; Striganov, S; Svoboda, R; Tang, Z; Tavartkiladze, Z; Townsend, L; Tulin, S; Vainshtein, A; Van Kooten, R; Wagner, C E M; Wang, Z; Wehring, B; Wilson, R J; Wise, M; Yokoyama, M; Young, A R

    2013-01-01

    This report, prepared for the Community Planning Study - Snowmass 2013 - summarizes the theoretical motivations and the experimental efforts to search for baryon number violation, focussing on nucleon decay and neutron-antineutron oscillations. Present and future nucleon decay search experiments using large underground detectors, as well as planned neutron-antineutron oscillation search experiments with free neutron beams are highlighted.

  19. Weak gravity conjecture as a razor criterium for exotic D-brane instantons

    Science.gov (United States)

    Addazi, Andrea

    2017-01-01

    We discuss implications of weak gravity conjecture (WGC) for exotic D-brane instantons. In particular, WGC leads to indirect stringent bounds on non-perturbative superpotentials generated by exotic instantons with many implications for phenomenology: R-parity violating processes, neutrino mass, μ-problem, neutron-antineutron transitions and collider physics.

  20. First Observation of the Decays $B^{0}\\to D^{*-}p\\overline {p}\\pi^{+}$ and $B ^{0}\\to D^{*-}p\\overline {n}$

    CERN Document Server

    Anderson, S; Kubota, Y; Lee, S J; Mahapatra, R; O'Neill, J J; Poling, R A; Riehle, T; Smith, A; Stepaniak, C J; Urheim, J; Ahmed, S; Alam, M S; Athar, S B; Jian, L; Ling, L; Saleem, M; Timm, S; Wappler, F; Anastassov, A; Duboscq, J E; Eckhart, E; Gan, K K; Gwon, C; Hart, T; Honscheid, K; Hufnagel, D; Kagan, H; Kass, R; Pedlar, T K; Schwarthoff, H; Thayer, J B; Von Törne, E; Zoeller, M M; Richichi, S J; Severini, H; Skubic, P L; Undrus, A; Chen, S; Fast, J; Hinson, J W; Lee, J; Miller, D H; Shibata, E I; Shipsey, I P J; Pavlunin, V; Cronin-Hennessy, D; Lyon, A L; Thorndike, E H; Jessop, C P; Marsiske, H; Perl, Martin Lewis; Savinov, V; Zhou, X; Coan, T E; Fadeev, V; Maravin, Y; Narsky, I; Stroynowski, R; Ye, J; Wlodek, T; Artuso, M; Ayad, R; Boulahouache, C; Bukin, K; Dambasuren, E; Karamov, S; Majumder, G; Moneti, G C; Mountain, R; Schuh, S; Skwarnicki, T; Stone, S; Viehhauser, G; Wang, J C; Wolf, A; Wu, J; Kopp, S E; Mahmood, A H; Csorna, S E; Danko, I; McLean, K W; Marka, S; Xu, Z; Godang, R; Kinoshita, K; Lai, I C; Schrenk, S; Bonvicini, G; Cinabro, D; McGee, S A; Perera, L P; Zhou, G J; Lipeles, E; Pappas, S P; Schmidtler, M; Shapiro, A; Sun, W M; Weinstein, A J; Würthwein, F; Jaffe, D E; Masek, G E; Paar, H P; Potter, E M; Prell, S; Sharma, V; Asner, D M; Eppich, A; Hill, T S; Morrison, R J; Briere, R A; Chen, G P; Behrens, B H; Ford, W T; Gritsan, A; Roy, J D; Smith, J G; Alexander, J P; Baker, R; Bebek, C; Berger, B E; Berkelman, K; Blanc, F; Boisvert, V; Cassel, David G; Dickson, M; Drell, P S; Ecklund, K M; Ehrlich, R; Foland, A D; Gaidarev, P B; Gibbons, L K; Gittelman, B; Gray, S W; Hartill, D L; Heltsley, B K; Hopman, P I; Jones, C D; Kreinick, D L; Lohner, M; Magerkurth, A; Meyer, T O; Mistry, N B; Nordberg, E; Patterson, J R; Peterson, D; Riley, D; Thayer, J G; Urner, D; Valant-Spaight, B L; Warburton, A; Avery, P; Prescott, C; Rubiera, A I; Yelton, J; Zheng, J; Brandenburg, G; Ershov, A; Gao, Y S; Kim, D Y J; Wilson, R; Browder, T E; Li, Y; Rodríguez, J L; Yamamoto, H; Bergfeld, T; Eisenstein, B I; Ernst, J; Gladding, G E; Gollin, G D; Hans, R M; Johnson, E; Karliner, I; Marsh, M A; Palmer, M; Plager, C; Sedlack, C; Selen, M; Thaler, J J; Williams, J; Edwards, K W; Janicek, R; Patel, P M; Sadoff, A J; Ammar, R; Bean, A; Besson, D; Davis, R; Kwak, N; Zhao, X

    2001-01-01

    We report the first observation of exclusive decays of the type B to D^* N anti-N X, where N is a nucleon. Using a sample of 9.7 times 10^{6} B-Bbar pairs collected with the CLEO detector operating at the Cornell Electron Storage Ring, we measure the branching fractions B(B^0 \\to D^{*-} proton antiproton \\pi^+) = ({6.5}^{+1.3}_{-1.2} +- 1.0) \\times 10^{-4} and B(B^0 \\to D^{*-} proton antineutron) = ({14.5}^{+3.4}_{-3.0} +- 2.7) times 10^{-4}. Antineutrons are identified by their annihilation in the CsI electromagnetic calorimeter.

  1. Project X: Physics Opportunities

    CERN Document Server

    Kronfeld, Andreas S; Al-Binni, Usama; Altmannshofer, Wolfgang; Ankenbrandt, Charles; Babu, Kaladi; Banerjee, Sunanda; Bass, Matthew; Batell, Brian; Baxter, David V; Berezhiani, Zurab; Bergevin, Marc; Bernstein, Robert; Bhattacharya, Sudeb; Bishai, Mary; Blum, Thomas; Bogacz, S Alex; Brice, Stephen J; Brod, Joachim; Bross, Alan; Buchoff, Michael; Burgess, Thomas W; Carena, Marcela; Castellanos, Luis A; Chattopadhyay, Subhasis; Chen, Mu-Chun; Cherdack, Daniel; Christ, Norman H; Chupp, Tim; Cirigliano, Vincenzo; Coloma, Pilar; Coppola, Christopher E; Cowsik, Ramanath; Crabtree, J Allen; Delahaye, Jean-Pierre; Denisov, Dmitri; deNiverville, Patrick; de Gouvêa, André; Dharmapalan, Ranjan; Dolgov, Alexander; Dvali, Georgi; Eichten, Estia; Engelfried, Jürgen; Ferguson, Phillip D; Gabriel, Tony; Gal, Avraham; Gallmeier, Franz; Ganezer, Kenneth S; Gardner, Susan; Glenzinski, Douglas; Godfrey, Stephen; Golubeva, Elena S; Gori, Stefania; Graves, Van B; Greene, Geoffrey; Griffard, Cory L; Haisch, Ulrich; Handler, Thomas; Hartfiel, Brandon; Hawari, Ayman; Heilbronn, Lawrence; Hill, James E; Huber, Patrick; Jaffe, David E; Johnson, Christian; Kamyshkov, Yuri; Kaplan, Daniel M; Kerbikov, Boris; Kiburg, Brendan; Kirk, Harold G; Klein, Andreas; Knoepfel, Kyle; Kopeliovich, Boris; Kopeliovich, Vladimir; Kopp, Joachim; Korsch, Wolfgang; Kribs, Graham; Lipton, Ronald; Liu, Chen-Yu; Lorenzon, Wolfgang; Lu, Zheng-Tian; Makins, Naomi C R; McKeen, David; Mills, Geoffrey; Mohapatra, Rabindra; Mokhov, Nikolai V; Mocko, Michael; Muhrer, Guenter; Mumm, Pieter; Okun, Lev; Neuffer, David; Palmer, Mark A; Palmer, Robert; Pattie, Robert W; Phillips, David G; Pronsikh, Vitaly; Pitts, Kevin; Pospelov, Maxim; Quigg, Chris; Ramberg, Erik; Ray, Amlan; Reimer, Paul E; Richards, David G; Ritz, Adam; Roy, Amit; Ruggles, Arthur; Ryne, Robert; Sarkar, Utpal; Saunders, Andy; Semertzidis, Yannis K; Serebrov, Anatoly; Shimizu, Hirohiko; Shrock, Robert; Snopok, Pavel V; Snow, William M; Sikdar, Arindam K; Soha, Aria; Spanier, Stefan; Striganov, Sergei; Tang, Zhaowen; Townsend, Lawrence; Urheim, Jon; Vainshtein, Arkady; Van Kooten, Richard J; Van de Water, Richard; Van de Water, Ruth S; Wehring, Bernard; Whitehead, Lisa; Wilson, Robert J; Worcester, Elizabeth; Young, Albert R; Wester, William C; Zeller, Geralyn

    2013-01-01

    Part 2 of "Project X: Accelerator Reference Design, Physics Opportunities, Broader Impacts". In this Part, we outline the particle-physics program that can be achieved with Project X, a staged superconducting linac for intensity-frontier particle physics. Topics include neutrino physics, kaon physics, muon physics, electric dipole moments, neutron-antineutron oscillations, new light particles, hadron structure, hadron spectroscopy, and lattice-QCD calculations.

  2. Some Comments on the Branching Ratios for n-bar p Annihilation into pipi, KK-bar , and pieta Channels

    Science.gov (United States)

    Kudryavtsev, A. E.

    2000-11-01

    We give some remarks on the $\\bar n p$-partial branching ratios in flight at low momenta of antineutron, measured by OBELIX collaboration. The comparison is made to the known branching ratios from the $p \\bar p$-atomic states. The branching ratio for the reaction $\\bar n p \\to \\pi^+\\pi^0$ is found to be suppressed in comparison to what follows from the $ p \\bar p$-data. It is also shown, that there is no so called dynamic I=0-amplitude suppression for the process $N\\bar N \\to K\\bar K$.

  3. Future prospects of baryon istability search in p-decay and n n(bar) oscillation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ball, S.J.; Kamyshkov, Y.A. [ed.

    1996-11-01

    These proceedings contain thirty-one papers which review both the theoretical and the experimental status and near future of baryon instability research. Baryon instability is investigated from the vantage point of supersymmetric and unified theories. The interplay between baryogenesis and antimatter is examined. Double beta decay experiments are discussed. The huge Icarus experiment is described with its proton decay capabilities. Neutron-antineutron oscillations investigations are presented, especially efforts with ultra-cold neutrons. Individual papers are indexed separately on the Energy Data Base.

  4. Realistic calculations of nuclear disappearance lifetimes induced by n nmacr oscillations

    Science.gov (United States)

    Friedman, E.; Gal, A.

    2008-07-01

    Realistic calculations of nuclear disappearance lifetimes induced by n nmacr oscillations are reported for oxygen and iron, using nmacr nuclear potentials derived from a recent comprehensive analysis of pmacr atomic X-ray and radiochemical data. A lower limit τn nmacr >3.3×108s on the n nmacr oscillation time is derived from the Super-Kamiokande I new lower limit Td(O)>1.77×1032yr on the neutron lifetime in oxygen. Antineutron scattering lengths in carbon and nickel, needed in trap experiments using ultracold neutrons, are calculated from updated Nmacr optical potentials at threshold, with results shown to be largely model independent.

  5. Processing of the signals from the Liquid Xenon Calorimeter for timing measurements

    Science.gov (United States)

    Epshteyn, L. B.; Grebenuyk, A. A.; Kozyrev, A. N.; Logashenko, I. B.; Mikhaylov, K. Yu.; Ruban, A. A.; Yudin, Yu. V.

    2017-02-01

    One of the goals of the Cryogenic Magnetic Detector at Budker Institute of Nuclear Physics SB RAS (Novosibirsk, Russia) is a study of hadron production in electron-positron collisions near threshold. The neutron-antineutron pair production events can be detected only by the calorimeters. In the barrel calorimeter the antineutron annihilation typically occurs about 5 ns or later after the beams crossing. For identification of such events it is necessary to measure the time of flight of particles to the LXe-calorimeter with an accuracy of about a few nanoseconds. The LXe-calorimeter consists of 14 layers of ionization chambers with two readout: anode and cathode. The duration of charge collection to the anodes is about 4.5 μs, while the required accuracy of measuring of the signal arrival time is less than 1/1000 of that (i.e. 4.5 ns). Besides, the signals' shapes differ substantially from event to event, so the signal arrival time is measured in two stages. In the paper we describ the development of the special electronics which performs waveform digitization and the on-line measurement of signals' arrival times and amplitudes.

  6. Baryon Number Violating Scalar Diquarks at the LHC

    CERN Document Server

    Baldes, Iason; Volkas, Raymond R

    2011-01-01

    Baryon number violating (BNV) processes are heavily constrained by experiments searching for nucleon decay and neutron-antineutron oscillations. If the baryon number violation occurs via the third generation quarks, however, we may be able to avoid the nucleon stability constraints, thus making such BNV interactions accessible at the LHC. In this paper we study a specific class of BNV extensions of the standard model (SM) involving diquark and leptoquark scalars. After an introduction to these models we study one promising extension in detail, being interested in particles with mass of O(TeV). We calculate limits on the masses and couplings from neutron-antineutron oscillations and dineutron decay for couplings to first and third generation quarks. We explore the possible consequences of such a model on the matter-antimatter asymmetry. We shall see that for models which break the global baryon minus lepton number symmetry, (B-L), the most stringent constraints come from the need to preserve a matter-antimatte...

  7. Exotic see-saw mechanism for neutrini and leptogenesis in a Pati-Salam model

    CERN Document Server

    Addazi, Andrea; Ricciardi, Giulia

    2015-01-01

    We discuss non-perturbative corrections to the neutrino sector, in the context of a D-brane Pati-Salam-like model, that can be obtained as a simple alternative to $SO(10)$ GUT's in theories with open and unoriented strings. In such D-brane models, exotic stringy instantons can correct the right-handed neutrino mass matrix in a calculable way, thus affecting mass hierarchies and modifying the see-saw mechanism to what we name exotic see-saw. For a wide range of parameters, a compact spectrum of right-handed neutrino masses can occur that gives rise to a predictive scenario for low energy observables. This model also provides a viable mechanism for Baryon Asymmetry in the Universe (BAU) through leptogenesis. Finally, a Majorana mass for the neutron is naturally predicted in the model, leading to potentially testable neutron-antineutron oscillations. Combined measurements in neutrino and neutron-antineutron sectors could provide precious informations on physics at the quantum gravity scale.

  8. Parity-doublet representation of Majorana fermions and neutron oscillation

    CERN Document Server

    Fujikawa, Kazuo

    2016-01-01

    We present a parity-doublet theorem for the representation of the intrinsic parity of Majorana fermions, which is expected to be useful also in condensed matter physics, and it is illustrated to provide a criterion of neutron-antineutron oscillation in a BCS-like effective theory with $\\Delta B=2$ baryon number violating terms. The CP violation in the present effective theory causes no direct CP violating effects in the oscillation itself, which is demonstrated by the exact solution, although it influences the neutron electric dipole moment in the leading order of small $\\Delta B=2$ parameters. An analogue of Bogoliubov transformation, which preserves P and CP, is crucial in the analysis.

  9. Dynamical R-parity violations from exotic instantons

    CERN Document Server

    Addazi, Andrea

    2015-01-01

    We show how R-parity can be dynamically broken by non-perturbative quantum gravity effects. In particular, in D-brane models, Exotic instantons provide a simple and calculable mechanism for the generation of R-parity violating bilinear, trilinear and higher order superpotential terms. We show examples of MSSM-like D-brane models, in which one Exotic Instanton induces only one term among the possible R-parity violating superpotentials. Naturally, the idea can be generalized for other gauge groups. As a consequence, a dynamical violation of R-parity does not necessarily destabilize the proton, {\\it i.e} a strong fine tuning is naturally avoided, in our case. For example, a Lepton violating superpotential term can be generated without generating Baryon violating ones, and {\\it viceversa}. This has strong implications in phenomenology: neutrino, neutron-antineutron, electric dipole moments, dark matter and LHC physics.

  10. Production of black holes and their angular momentum distribution in models with split fermions

    CERN Document Server

    Dai, D C; Stojkovic, D; Dai, De-Chang; Starkman, Glenn D.; Stojkovic, Dejan

    2006-01-01

    In models with TeV-scale gravity it is expected that mini black holes will be produced in near-future accelerators. On the other hand, TeV-scale gravity is plagued with many problems like fast proton decay, unacceptably large neutron-antineutron oscillations, flavor changing neutral currents, large mixing between leptons, etc. Most of these problems can be solved if different fermions are localized at different points in the extra dimensions. We study the cross-section for the production of black holes and their angular momentum distribution in these models with "split" fermions. We find that, for a fixed value of the fundamental mass scale, the total production cross section is reduced compared with models where all the fermions are localized at the same point in the extra dimensions. Fermion splitting also implies that the bulk component of the black hole angular momentum must be taken into account in studies of the black hole decay via Hawking radiation.

  11. The NNbar Experiment at the European Spallation Source

    CERN Document Server

    Frost, M J

    2016-01-01

    The observation of neutron to antineutron oscillation would be the first experimental evidence to show that baryon number is not a conserved quantity. It also provides an answer to the hypothesized post-sphaleron baryogenesis mechanism shortly after the Big Bang. The free oscillation time {\\tau_{n\\rightarrow\\bar{n}} has a lower limit at 8.7 x 10^7 seconds determined at ILL in 1994. Current beyond Standard Model theories of this oscillation time estimate the value to be on the order of 10^{10} seconds. A new experiment is proposed at the European Spallation Source that has 1000 times the sensitivity of the previous experiment, and would confirm the viability of those beyond Standard Model theories.

  12. Antinucleon-nucleus interaction near threshold from the Paris $\\bar NN$ potential

    CERN Document Server

    Friedman, E; Loiseau, B; Wycech, S

    2015-01-01

    A general algorithm for handling the energy dependence of hadron-nucleon amplitudes in the nuclear medium, consistently with their density dependence, has been recently applied to antikaons, eta mesons and pions interacting with nuclei. Here we apply this approach to antiprotons below threshold, analyzing experimental results for antiprotonic atoms across the periodic table. It is also applied to antiproton and antineutron interaction with nuclei up to 400~MeV/c, comparing with elastic scattering and annihilation cross sections. The underlying $\\bar pN$ scattering amplitudes are derived from the Paris $\\bar NN$ potential, including modifications in the medium. Emphasis is placed on the role of the $P$-wave amplitudes with respect to the repulsive $S$-wave amplitudes.

  13. Professor Walter Oelert, leader of the team which created the first atoms of antihydrogen at the Low Energy Antiproton Ring (LEAR) in January 1996

    CERN Multimedia

    Laurent Guiraud

    1996-01-01

    Antiparticles were predicted in the work of Paul Dirac in the 1920's, since when physicists have identified all the necessary antiparticle constituents of an antiparticle atom - antielectrons (positrons), antiprotons and antineutrons. However, an antihydrogen atom wasn't produced until the PS210 experiment at CERN in 1995. PS210 used the LEAR accelerator, which was then nearing the end of its lifetime, so everything in the experiment had to work first time. After installing the equipment in spring 1995, the experiment took place in the autumn, in two hour periods over 4 weeks. The experiment team collided energetic antiprotons from LEAR with a heavy element, a challenge for them as well as the LEAR operators. Proving that antihydrogen atoms had been formed required several more weeks of data analysis, but the announcement that nine antihydrogen atoms had been produced came on 4 January 1996.

  14. Long distance propagation of a polarized neutron beam in zero magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, U.; Bitter, T.; El-Muzeini, P. (Heidelberg Univ. (Germany). Physikalisches Inst.); Dubbers, D. (Technische Univ. Muenchen, Garching (Germany). Fakultaet fuer Physik E21); Schaerpf, O. (Inst. Laue Langevin, 38 - Grenoble (France))

    1992-09-01

    A beam of fully polarized cold neutrons was transported through a zero magnetic field region of 70 m length without loss of polarization. The purpose of this exercise was twofold: Firstly, to demonstrate that the new zero-field neutron spin-echo method will work also for very long neutron flight paths; secondly, to prove in the most direct way that the neutron free-flight region of the ILL neutron-antineutron oscillation experiment was indeed sufficiently field-free ('quasifree condition') by using the neutrons themselves as a magnetometer. To this purpose the residual magnetic field integrals in the long 'zero-field' region were measured with a conventional neutron spin-echo method. The overall spin precession angle of the neutrons during their flight through the long zero-field region was found to be less than 2[sup 0]. (orig.).

  15. String completion of an SU(3c⊗SU(3L⊗U(1X electroweak model

    Directory of Open Access Journals (Sweden)

    Andrea Addazi

    2016-08-01

    Full Text Available The extended electroweak SU(3c⊗SU(3L⊗U(1X symmetry framework “explaining” the number of fermion families is revisited. While 331-based schemes can not easily be unified within the conventional field theory sense, we show how to do it within an approach based on D-branes and (unoriented open strings, on Calabi–Yau singularities. We show how the theory can be UV-completed in a quiver setup, free of gauge and string anomalies. Lepton and baryon numbers are perturbatively conserved, so neutrinos are Dirac-type, and their lightness results from a novel TeV scale seesaw mechanism. Dynamical violation of baryon number by exotic instantons could induce neutron–antineutron oscillations, with proton decay and other dangerous R-parity violating processes strictly forbidden.

  16. The search for n-nbar oscillation in Super-Kamiokande I

    CERN Document Server

    Hayato, Y; Ishihara, K; Kameda, J; Koshio, Y; Minamino, A; Mitsuda, C; Miura, M; Moriyama, S; Nakahata, M; Obayashi, Y; Ogawa, H; Sekiya, H; Shiozawa, M; Suzuki, Y; Takeda, A; Takeuchi, Y; Ueshima, K; Watanabe, H; Higuchi, I; Ishihara, C; Ishitsuka, M; Kajita, T; Kaneyuki, K; Mitsuka, G; Nakayama, S; Nishino, H; Okumura, K; Saji, C; Takenaga, Y; Clark, S; Desai, S; Dufour, F; Herfurth, A; Kearns, E; Likhoded, S; Litos, M; Raaf, J L; Stone, J L; Sulak, L R; Wang, W; Goldhaber, M; Casper, D; Cravens, J P; Dunmore, J; Griskevich, J; Kropp, W R; Liu, D W; Mine, S; Regis, C; Smy, M B; Sobel, H W; Vagins, M R; Ganezer, K S; Hartfiel, B; Hill, J; Keig, W E; Jang, J S; Jeoung, I S; Kim, J Y; Lim, I T; Scholberg, K; Tanimoto, N; Walter, C W; Wendell, R; Ellsworth, R W; Tasaka, S; Guillian, G; Learned, J G; Matsuno, S; Messier, M D; Ichikawa, A K; Ishida, T; Ishii, T; Iwashita, T; Kobayashi, T; Nakadaira, T; Nakamura, K; Nishikawa, K; Nitta, K; Oyama, Y; Suzuki, A T; Hasegawa, M; Maesaka, H; Nakaya, T; Sasaki, T; Sato, H; Tanaka, H; Yamamoto, S; Yokoyama, M; Haines, T J; Dazeley, S; Hatakeyama, S; Svoboda, R; Sullivan, G W; Gran, R; Habig, A; Fukuda, Y; Itow, Y; Koike, T; Jung, C K; Kato, T; Kobayashi, K; McGrew, C; Sarrat, A; Terri, R; Yanagisawa, C; Tamura, N; Ikeda, M; Sakuda, M; Kuno, Y; Yoshida, M; Kim, S B; Yang, B S; Ishizuka, T; Okazawa, H; Choi, Y; Seo, H K; Gando, Y; Hasegawa, T; Inoue, K; Ishii, H; Nishijima, K; Ishino, H; Watanabe, Y; Koshiba, M; Totsuka, Y; Chen, S; Deng, Z; Liu, Y; Kielczewska, D; Berns, H G; Shiraishi, K K; Thrane, E; Washburn, K; Wilkes, R J

    2011-01-01

    A search for neutron-antineutron (n - nbar) oscillation, a process with |\\DeltaB| = 2 that has been predicted by right-left (R-L) symmetric gauge theories, was undertaken using the 24.5\\times10^33 neutron-yrs exposure of Super- Kamiokande I, in an analysis that included the significant sources of experimental uncertainties. No evidence for n - nbar oscillation was found, the lower limit of the lifetime for neutrons bound in ^16 O was determined to be 1.89 \\times 10^32 yrs at the 90% confidence level (C.L.), and the corresponding limit for the oscillation time for free neutrons was calculated to be 2.44 \\times 10^8 sec using a theoretical suppression factor of 1.0 \\times 10^23 sec^-1.

  17. String completion of an $\\mathrm{SU(3)_c \\otimes SU(3)_L \\otimes U(1)_X}$ electroweak model

    CERN Document Server

    Addazi, Andrea; Vaquera-Araujo, C A

    2016-01-01

    The extended electroweak $\\mathrm{SU(3)_c \\otimes SU(3)_L \\otimes U(1)_X}$ symmetry framework "explaining" the number of fermion families is revisited. While $331$-based schemes can not easily be unified within the conventional field theory sense, we show how to do it within an approach based on D-branes and (un)oriented open strings, on Calabi-Yau singularities. We show how the theory can be UV-completed in a quiver setup, free of gauge and string anomalies. Lepton and baryon numbers are perturbatively conserved, so neutrinos are Dirac-type, and their lightness results from a novel TeV scale seesaw mechanism. Dynamical violation of baryon number by exotic instantons could induce neutron-antineutron oscillations, with proton decay and R-parity violation strictly forbidden.

  18. Measurement of the $\\bar{p}p \\rightarrow \\bar{n}n$ Charge-Exchange Differential Cross-Section

    CERN Multimedia

    2002-01-01

    The aim of this proposal is a measurement of the differential cross-section of the $\\bar{p}$p $\\rightarrow$ $\\bar{n}$n charge-exchange reaction with a point-to-point precision of 1\\% in the forward direction, and an absolute normalization error of 3\\%. The high precision of the data should allow, inter alia, a determination of the $\\pi$NN coupling constant to better than 2\\%.\\\\ \\\\ The measurement will be done using the existing neutron and antineutron detectors built for experiment PS199 and liquid hydrogen target. In one week of running time, with a $\\bar{p}$ beam intensity of 3 $ 10 ^{5} $ $\\bar{p}$/sec, the reaction will be measured at a few $\\bar{p}$ momenta, in the range 500 to 900~MeV/c.

  19. Low-energy antinucleon-nucleus interaction revisited

    Science.gov (United States)

    Friedman, E.

    2015-08-01

    Annihilation cross sections of antiprotons and antineutrons on the proton between 50 and 400 MeV/c show Coulomb focusing below 200 MeV/c and almost no charge-dependence above 200 MeV/c. Similar comparisons for heavier targets are not possible for lack of overlap between nuclear targets studied with and beams. Interpolating between -nucleus annihilation cross sections with the help of an optical potential to compare with -nucleus annihilation cross sections reveal unexpected features of Coulomb interactions in the latter. Direct comparisons between -nucleus and -nucleus annihilations at very low energies could be possible if cross sections are measured on the same targets and at the same energies as the available cross sections for . Such measurements may be feasible in the foreseeable future.

  20. Antinucleon-nucleus interaction near threshold from the Paris N bar N potential

    Science.gov (United States)

    Friedman, E.; Gal, A.; Loiseau, B.; Wycech, S.

    2015-11-01

    A general algorithm for handling the energy dependence of hadron-nucleon amplitudes in the nuclear medium, consistently with their density dependence, has been recently applied to antikaons, eta mesons and pions interacting with nuclei. Here we apply this approach to antiprotons below threshold, analyzing experimental results for antiprotonic atoms across the periodic table. It is also applied to antiproton and antineutron interactions with nuclei up to 400 MeV/c, comparing with elastic scattering and annihilation cross sections. The underlying p bar N scattering amplitudes are derived from the Paris N bar N potential, including in-medium modifications. Emphasis is placed on the role of the P-wave amplitudes with respect to the repulsive S-wave amplitudes.

  1. String completion of an SU(3)c ⊗ SU(3)L ⊗ U(1)X electroweak model

    Science.gov (United States)

    Addazi, Andrea; Valle, J. W. F.; Vaquera-Araujo, C. A.

    2016-08-01

    The extended electroweak SU(3)c ⊗ SU(3)L ⊗ U(1)X symmetry framework "explaining" the number of fermion families is revisited. While 331-based schemes can not easily be unified within the conventional field theory sense, we show how to do it within an approach based on D-branes and (un)oriented open strings, on Calabi-Yau singularities. We show how the theory can be UV-completed in a quiver setup, free of gauge and string anomalies. Lepton and baryon numbers are perturbatively conserved, so neutrinos are Dirac-type, and their lightness results from a novel TeV scale seesaw mechanism. Dynamical violation of baryon number by exotic instantons could induce neutron-antineutron oscillations, with proton decay and other dangerous R-parity violating processes strictly forbidden.

  2. В поисках альтернативы (Новая космологическая концепция без «Большого Взрыва»

    Directory of Open Access Journals (Sweden)

    Джахая Л. Г.

    2015-02-01

    Full Text Available Metagalaxy in finite spatial and temporal boundaries is qualitatively certain material formation, a single, coherent financial system in the boundless expanse of the universe. Material substrate is Metagalaxy metagalactic vacuum as a real physical environment and the arena of action of all material processes in the Metagalaxy. In Metagalaxy there are two types of interactions: gravity and electromagnetism are two excited states Metagalactic vacuum, all the other interactions ("weak", "strong" are the consequence of these two fundamental interactions. Inertial motion of the real weight in a vacuum explains the paradox of d'Alembert-Euler, and gravity - "rolling up" in the "potential well" real masses and "black holes". The main feature of the metagalactic vacuum is its unequal optical density. In addition to the local optical inhomogeneities with the index of refraction greater than unity (n>1, the giant optical inhomogeneity is all metagalactic vacuum, with a maximum optical density (nmax in the center of Metagalaxy, c (n =1 "here" and "now" ("Time of Life " and then to (n <1 on the periphery of the Metagalaxy and s (n = 0 at its edge. At the heart of the author's cosmological model is based on two laws: the creation of pairs of particles and antiparticles in strong gravitational fields of rotating "cosmological black holes" and the Magnus effect. It's enough to born neutron-antineutrons páry, they scatter in opposite directions, and neutrons, according to the Magnus effect, go into outer space, and be absorbed antineutrons "black hole", all the remaining particles are obtained in the beta decay of a neutron into a proton, an electron and antineutrinos and is ready hydrogen. This calibration will gather around the "cosmological black hole" isotopes of hydrogen atoms (75% and helium (25%, which will form protogalaxies - on the principle of "one cosmological black hole - one protogalaxy" with a primary hydrogen-helium cloud, it is ejected from

  3. Golden Jubilee photos: Welcome to the antiworld

    CERN Multimedia

    2004-01-01

    Professor Walter Oelert, leader of the team which created the first atoms of antihydrogen at the LEAR (Low Energy Antiproton Ring).Antiparticles were predicted in the work of Paul Dirac in the 1920's, since when physicists have identified all the necessary antiparticle constituents of an antiparticle atom - antielectrons (positrons), antiprotons and antineutrons. However, an antihydrogen atom wasn't produced until the PS210 experiment at CERN in 1995. PS210 used the LEAR accelerator, which was then nearing the end of its lifetime (see Bulletin 28/04), so everything in the experiment had to work first time. After installing the equipment in spring 1995, the experiment took place in the autumn, in two hour periods over 4 weeks. The experiment team collided energetic antiprotons from LEAR with a heavy element, a challenge for them as well as the LEAR operators. Proving that antihydrogen atoms had been formed required several more weeks of data analysis, but the announcement that nine antihydrogen atoms had been ...

  4. The coarsening effect of SA508-3 steel used as heavy forgings material

    Directory of Open Access Journals (Sweden)

    Dingqian Dong

    2015-01-01

    Full Text Available SA508Gr.3 steel is popularly used to produce core unit of nuclear power reactors due to its outstanding ability of anti-neutron irradiation and good fracture toughness. The forging process takes important role in manufacturing to refine the grain size and improve the material properties. But due to their huge size, heavy forgings cannot be cooled down quickly, and the refined grains usually have long time to grow in high temperature conditions. If the forging process is not adequately scheduled or implemented, very large grains up to millimetres in size may be found in this steel and cannot be eliminated in the subsequent heat treatment. To fix the condition which may causes the coarsening of the steel, hot upsetting experiments in the industrial production environment were performed under different working conditions and the corresponding grain sizes were measured and analysed. The observation showed that the grain will abnormally grow if the deformation is less than a critical value. The strain energy takes a critical role in the grain evolution. If dynamic recrystallization consumes the strain energy as much as possible, the normal grains will be obtained. While if not, the stored strain energy will promote abnormal growth of the grains.

  5. Measurement of Antiproton-proton Cross-Sections at Low Antiproton Momenta

    CERN Multimedia

    2002-01-01

    The experiment is designed to measure four different cross sections in the momentum range 150~MeV/c to 600~MeV/c: 1)~~~~the differential elastic \\\\ \\\\ 2)~~~~the differential charge exchange\\\\ \\\\ 3)~~~~the annihilation into charged and neutral pions\\\\ \\\\ 4)~~~~and the total cross section via the optical theorem. \\\\ \\\\ The experiment allows one to search once again and with good precision for baryonium. Of special interest is the existence of the S-meson, for which a signal of about 20~MeV-mb was found in a 1981 experiment (performed in the East Hall).\\\\ \\\\ A second point of special interest is the momentum region below 300~MeV/c because the cross sections are basically unknown. We will be able to explore the momentum dependence of this region for the first time.\\\\ \\\\ The elastic cross section is measured by a cylindrical multiwire proportional chamber and a scintillator hodoscope placed around a scattering chamber under vacuum. The charge exchange cross section is measured by a ring of 32~anti-neutron detector...

  6. Utilization of FADC for reconstruction and analysis of the background data in the Chooz neutrino experiment; Utilisation des FADC pour la reconstruction et l`analyse des donnees de bruit de fond dans l`experience neutrino de Chooz

    Energy Technology Data Exchange (ETDEWEB)

    Veron, Didier [Universite Claude Bernard, 69 - Lyon (France)

    1997-03-25

    This thesis describes a particular contribution to the Chooz experiment. The latter looks for the oscillations, over a distance of 1 km, of antineutrons emitted by two nuclear reactors. The electron-type antineutrinos are detected through their inverse beta interaction with a target`s proton. The neutron is detected through its capture by a gadolinium nucleus revealed by an 8 MeV gamma emission. In the first part we describe the reconstruction of events as simulated by the GIANT software. We show that the positron`s and neutron`s stopping point can actually be reconstructed with an accuracy of 10 and 20 cm respectively. In the second part, we proceed to the analysis of the calibration`s data as recorded with Fast Wave Form Digitizers. This confirms the reliability of the Monte-Carlo results and allows measurement of both the neutrons` capture probability and time by the target gadolinium. The last part deals with the background (reactor turned off) data analysis and the pin-pointing of its various sources. In order to reduce their contribution, we define spatial cuts. These cuts` reliability is validated by analysis of data obtained not only with a neutron source, but also with neutrons issued from cosmic rays. We end up with a background contribution of two to three events per day, about ten times less than the expected neutrino rate at full reactor power. (author) 81 refs., 152 figs.,43 tabs.

  7. Electron-Positron to Nucleon-Antinucleon Pair at Threshold and Proton Form Factor

    CERN Document Server

    Yan, Y; Kobdaj, C; Suebka, P

    2009-01-01

    The reactions of electron-positron to nucleon-antinucleon pair at energy threshold are studied in a non-perturbative quark model. The puzzling experimental result that the ratio of the cross section of electron-positron to proton-antiproton to the one of electron-positron to neutron-antineutron is smaller than 1 can be understood in the framework of the phenomenological nonrelativistic quark model and the theoretical predictions for the time-like proton form factor at energy threshold are well consistent with the experimental data. The work suggests that the two-step process, in which the primary quark-antiquark pair forms first a vector meson which in turn decays into a hadron pair, is dominant over the one-step process in which the primary quark-antiquark pair is directly dressed by additional quark-antiquark pairs to form a hadron pair. The experimental data on the reactions of electron-positron to nucleon-antinucleon strongly suggest the reported vector meson omega(1930) to be a 2D-wave particle, while th...

  8. Modeling of the Near-Earth Low-Energy Antiproton Fluxes

    Directory of Open Access Journals (Sweden)

    U. B. Jayanthi

    2011-01-01

    Full Text Available The local interstellar antiproton spectrum is simulated taking into account antineutron decay, (He,p interaction, secondary and tertiary antiproton production, and the solar modulation in the “force field” approximation. Inclusive invariant cross-sections were obtained through a Monte Carlo procedure using the Multistage Dynamical Model code simulating various processes of the particle production. The results of the simulations provided flux values of 4⋅10−3 to 10−2 and 10−2 to 1.7⋅10−2 antiprotons/(2 s sr GeV at energies of 0.2 and 1 GeV, respectively, for the solar maximum and minimum epochs. Simulated flux of the trapped antiprotons in the inner magnetosphere due to galactic cosmic ray (GCR interactions with the atmospheric constituents exceeds the galactic antiproton flux up to several orders. These simulation results considering the assumptions with the attendant limitations are in comprehensive agreement with the experimental data including the PAMELA ones.

  9. Two loop unification of non-SUSY SO(10) GUT with TeV scalars

    Science.gov (United States)

    Brennan, T. Daniel

    2017-03-01

    In this paper we examine gauge coupling unification of the non-SUSY SO(10) grand unified theory proposed by Babu and Mohapatra [Phys. Lett. B 715, 328 (2012), 10.1016/j.physletb.2012.08.006] at the two loop level. This theory breaks down to the standard model in a single step and has the distinguishing feature of TeV nonstandard model scalars. This leads to a plethora of interesting new physics at the TeV scale and the discovery of new particles at the LHC. This model gives rise to testable proton decay, neutron-antineutron oscillations, provides a mechanism for baryogenesis, and contains potential dark matter candidates. In this paper, we compute the two loop beta function and show that this model unifies to two loop order around 1 015 GeV . We then compute the proton lifetime, taking into account threshold effects and show that these effects place it above the Super-Kamiokande limit [K. Abe et al. (Super-Kamiokande Collaboration), Phys. Rev. D 95, 012004 (2017)., 10.1103/PhysRevD.95.012004].

  10. Study of $ \\bar{p} $ and $ \\bar{n} $ annihilations at LEAR with OBELIX, a large acceptance and high resolution detector based on the Open Axial Field Spectrometer

    CERN Multimedia

    2002-01-01

    % PS201 Study of $\\bar{p}$ and $\\bar{n}$ annihilations at LEAR with OBELIX, a large acceptance and high resolution detector based on the Open Axial Field Spectrometer \\\\ \\\\OBELIX is designed to study exclusive final states of antiproton and antineutron annihilations at low energies with protons and nuclei. \\\\ \\\\The physics motivations of the experiment are:\\\\ \\\\\\begin{itemize} \\item (gg, ggg), hybrids ($ q \\bar{q} g $), multiquarks ($ q q \\bar{q} \\bar{q} $) and light mesons ($ q \\bar{q} $) produced in $ N \\bar{N} $ annihilations and study of their spectroscopy and decays. Also broad structures will be searched for by comparing identical decay modes in exclusive final states of the same type occuring from initial states with different angular momentum or isospin. \\item Study of the dynamics of $ N \\bar{N} $ interactions and of the dependence of the final and intermediate resonant states of annihilation upon the quantum numbers of the initial $ N \\bar{N} $ state (angular momentum: S and P-wave in $\\bar{p}p $ at...

  11. R-Parity violation in F-Theory

    CERN Document Server

    Romão, Miguel Crispim; King, Stephen F; Leontaris, George K; Meadowcroft, Andrew K

    2016-01-01

    We discuss R-parity violation (RPV) in semi-local and local F-theory constructions. We first present a detailed analysis of all possible combinations of RPV operators arising from semi-local F-theory spectral cover constructions, assuming an $SU(5)$ GUT. We provide a classification of all possible allowed combinations of RPV operators originating from operators of the form $10\\cdot \\bar 5\\cdot \\bar 5$, including the effect of $U(1)$ fluxes with global restrictions. We then relax the global constraints and perform explicit computations of the bottom/tau and RPV Yukawa couplings, at an $SO(12)$ local point of enhancement in the presence of general fluxes subject only to local flux restrictions. We compare our results to the experimental limits on each allowed RPV operator, and show that operators such as $LLe^c$, $LQd^c$ and $u^cd^cd^c$ may be present separately within current bounds, possibly on the edge of observability, suggesting lepton number violation or neutron-antineutron oscillations as possible signal...

  12. Study of $J/\\psi\\to p\\bar{p}$ and $J/\\psi\\to n\\bar{n}$

    CERN Document Server

    Ablikim, M; Ambrose, D J; An, F F; An, Q; An, Z H; Bai, J Z; Ferroli, R B; Ban, Y; Becker, J; Berger, N; Bertani, M B; Bian, J M; Boger, E; Bondarenko, O; Boyko, I; Briere, R A; Bytev, V; Cai, X; Calcaterra, A C; Cao, G F; Chang, J F; Chelkov, G; Chen, G; Chen, H S; Chen, J C; Chen, M L; Chen, S J; Chen, Y; Chen, Y B; Cheng, H P; Chu, Y P; Cronin-Hennessy, D; Dai, H L; Dai, J P; Dedovich, D; Deng, Z Y; Denig, A; Denysenko, I; Destefanis, M; Ding, W M; Ding, Y; Dong, L Y; Dong, M Y; Du, S X; Fang, J; Fang, S S; Fava, L; Feldbauer, F; Feng, C Q; Fu, C D; Fu, J L; Gao, Y; Geng, C; Goetzen, K; Gong, W X; Gradl, W; Greco, M; Gu, M H; Gu, Y T; Guan, Y H; Guo, A Q; Guo, L B; Guo, Y P; Han, Y L; Hao, X Q; Harris, F A; He, K L; He, M; He, Z Y; Held, T; Heng, Y K; Hou, Z L; Hu, H M; Hu, J F; Hu, T; Huang, B; Huang, G M; Huang, J S; Huang, X T; Huang, Y P; Hussain, T; Ji, C S; Ji, Q; Ji, X B; Ji, X L; Jia, L K; Jiang, L L; Jiang, X S; Jiao, J B; Jiao, Z; Jin, D P; Jin, S; Jing, F F; Kalantar-Nayestanaki, N; Kavatsyuk, M; Kuehn, W; Lai, W; Lange, J S; Leung, J K C; Li, C H; Li, Cheng; Li, Cui; Li, D M; Li, F; Li, G; Li, H B; Li, J C; Li, K; Li, Lei; Li, N B; Li, Q J; Li, S L; Li, W D; Li, W G; Li, X L; Li, X N; Li, X Q; Li, X R; Li, Z B; Liang, H; Liang, Y F; Liang, Y T; Liao, G R; Liao, X T; Liu, B J; Liu, B J; Liu, C L; Liu, C X; Liu, C Y; Liu, F H; Liu, Fang; Liu, Feng; Liu, H; Liu, H B; Liu, H H; Liu, H M; Liu, H W; Liu, J P; Liu, Kun; Liu, Kai; Liu, K Y; Liu, P L; Liu, S B; Liu, X; Liu, X H; Liu, Y B; Liu, Y; Liu, Z A; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H; Lu, G R; Lu, H J; Lu, J G; Lu, Q W; Lu, X R; Lu, Y P; Luo, C L; Luo, M X; Luo, T; Luo, X L; Lv, M; Ma, C L; Ma, F C; Ma, H L; Ma, Q M; Ma, S; Ma, T; Ma, X Y; Ma, Y; Maas, F E; Maggiora, M; Malik, Q A; Mao, H; Mao, Y J; Mao, Z P; Messchendorp, J G; Min, J; Min, T J; Mitchell, R E; Mo, X H; Morales, C Morales; Motzko, C; Muchnoi, N Yu; Nefedov, Y; Nicholson, C; Nikolaev, I B; Ning, Z; Olsen, S L; Ouyang, Q; Pacetti, S P; Park, J W; Pelizaeus, M; Peters, K; Ping, J L; Ping, R G; Poling, R; Prencipe, E; Pun, C S J; Qi, M; Qian, S; Qiao, C F; Qin, X S; Qin, Y; Qin, Z H; Qiu, J F; Rashid, K H; Rong, G; Ruan, X D; Sarantsev, A; Schulze, J; Shao, M; Shen, C P; Shen, X Y; Sheng, H Y; Shepherd, M R; Song, X Y; Spataro, S; Spruck, B; Sun, D H; Sun, G X; Sun, J F; Sun, S S; Sun, X D; Sun, Y J; Sun, Y Z; Sun, Z J; Sun, Z T; Tang, C J; Tang, X; Thorndike, E H; Tian, H L; Toth, D; Ulrich, M U; Varner, G S; Wang, B; Wang, B Q; Wang, K; Wang, L L; Wang, L S; Wang, M; Wang, P; Wang, P L; Wang, Q; Wang, Q J; Wang, S G; Wang, X F; Wang, X L; Wang, Y D; Wang, Y F; Wang, Y Q; Wang, Z; Wang, Z G; Wang, Z Y; Wei, D H; Weidenkaff, P; Wen, Q G; Wen, S P; Werner, M W; Wiedner, U; Wu, L H; Wu, N; Wu, S X; Wu, W; Wu, Z; Xia, L G; Xiao, Z J; Xie, Y G; Xiu, Q L; Xu, G F; Xu, G M; Xu, H; Xu, Q J; Xu, X P; Xu, Y; Xu, Z R; Xue, F; Xue, Z; Yan, L; Yan, W B; Yan, Y H; Yang, H X; Yang, T; Yang, Y; Yang, Y X; Ye, H; Ye, M; Ye, M H; Yu, B X; Yu, C X; Yu, J S; Yu, S P; Yuan, C Z; Yuan, W L; Yuan, Y; Zafar, A A; Zallo, A Z; Zeng, Y; Zhang, B X; Zhang, B Y; Zhang, C C; Zhang, D H; Zhang, H H; Zhang, H Y; Zhang, J; Zhang, J G; Zhang, J Q; Zhang, J W; Zhang, J Y; Zhang, J Z; Zhang, L; Zhang, S H; Zhang, T R; Zhang, X J; Zhang, X Y; Zhang, Y; Zhang, Y H; Zhang, Y S; Zhang, Z P; Zhang, Z Y; Zhao, G; Zhao, H S; Zhao, J W; Zhao, K X; Zhao, Lei; Zhao, Ling; Zhao, M G; Zhao, Q; Zhao, S J; Zhao, T C; Zhao, X H; Zhao, Y B; Zhao, Z G; Zhemchugov, A; Zheng, B; Zheng, J P; Zheng, Y H; Zheng, Z P; Zhong, B; Zhong, J; Zhou, L; Zhou, X K; Zhou, X R; Zhu, C; Zhu, K; Zhu, K J; Zhu, S H; Zhu, X L; Zhu, X W; Zhu, Y M; Zhu, Y S; Zhu, Z A; Zhuang, J; Zou, B S; Zou, J H; Zuo, J X

    2012-01-01

    The decays $J/\\psi\\to p\\bar{p}$ and $J/\\psi\\to n\\bar{n}$ have been investigated with a sample of 225.2 million $J/\\psi$ events collected with the BESIII detector at the BEPCII $e^+e^-$ collider. The branching fractions are determined to be $\\mathcal{B}(J/\\psi\\to p\\bar{p})=(2.112\\pm0.004\\pm0.031)\\times10^{-3}$ and $\\mathcal{B}(J/\\psi\\to n\\bar{n})=(2.07\\pm0.01\\pm0.17)\\times10^{-3}$. Distributions of the angle $\\theta$ between the proton or anti-neutron and the beam direction are well described by the form $1+\\alpha\\cos^2\\theta$, and we find $\\alpha=0.595\\pm0.012\\pm0.015$ for $J/\\psi\\to p\\bar{p}$ and $\\alpha=0.50\\pm0.04\\pm0.21$ for $J/\\psi\\to n\\bar{n}$. Our branching-fraction results suggest a large phase angle between the strong and electromagnetic amplitudes describing the $J/\\psi\\to N\\bar{N}$ decay.

  13. Explaining the CMS excesses, baryogenesis and neutrino masses in $E_{6}$ motivated $U(1)_{N}$ model

    CERN Document Server

    Dhuria, Mansi; Sarkar, Utpal

    2016-01-01

    We study the superstring inspired $E_{6}$ model motivated $U(1)_{N}$ extension of the supersymmetric standard model to explore the possibility of explaining the recent excess CMS events and the baryon asymmetry of the universe in eight possible variants of the model. In light of the hints from short-baseline neutrino experiments at the existence of one or more light sterile neutrinos, we also study the neutrino mass matrices dictated by the field assignments and the discrete symmetries in these variants. We find that all the variants can explain the excess CMS events via the exotic slepton decay, while for a standard choice of the discrete symmetry four of the variants have the feature of allowing high scale baryogenesis (leptogenesis). For one other variant three body decay induced soft baryogenesis mechanism is possible which can induce baryon number violating neutron-antineutron oscillation. We also point out a new discrete symmetry which has the feature of ensuring proton stability and forbidding tree lev...

  14. Explaining the CMS excesses, baryogenesis, and neutrino masses in a E6 motivated U (1 )N model

    Science.gov (United States)

    Dhuria, Mansi; Hati, Chandan; Sarkar, Utpal

    2016-01-01

    We study the superstring inspired E6 model motivated U (1 )N extension of the supersymmetric standard model to explore the possibility of explaining the recent excess CMS events and the baryon asymmetry of the Universe in eight possible variants of the model. In light of the hints from short-baseline neutrino experiments at the existence of one or more light sterile neutrinos, we also study the neutrino mass matrices dictated by the field assignments and the discrete symmetries in these variants. We find that all the variants can explain the excess CMS events via the exotic slepton decay, while for a standard choice of the discrete symmetry four of the variants have the feature of allowing high scale baryogenesis (leptogenesis). For one other variant three body decay induced soft baryogenesis mechanism is possible which can induce baryon number violating neutron-antineutron oscillation. We also point out a new discrete symmetry which has the feature of ensuring proton stability and forbidding tree level flavor changing neutral current processes while allowing for the possibility of high scale leptogenesis for two of the variants. On the other hand, neutrino mass matrix of the U (1 )N model variants naturally accommodates three active and two sterile neutrinos which acquire masses through their mixing with extra neutral fermions giving rise to interesting textures for neutrino masses.

  15. Observation of the antimatter helium-4 nucleus.

    Science.gov (United States)

    2011-05-19

    High-energy nuclear collisions create an energy density similar to that of the Universe microseconds after the Big Bang; in both cases, matter and antimatter are formed with comparable abundance. However, the relatively short-lived expansion in nuclear collisions allows antimatter to decouple quickly from matter, and avoid annihilation. Thus, a high-energy accelerator of heavy nuclei provides an efficient means of producing and studying antimatter. The antimatter helium-4 nucleus (4He), also known as the anti-α (α), consists of two antiprotons and two antineutrons (baryon number B = -4). It has not been observed previously, although the α-particle was identified a century ago by Rutherford and is present in cosmic radiation at the ten per cent level. Antimatter nuclei with B Collider (RHIC; ref. 6) in 10(9) recorded gold-on-gold (Au+Au) collisions at centre-of-mass energies of 200 GeV and 62 GeV per nucleon-nucleon pair. The yield is consistent with expectations from thermodynamic and coalescent nucleosynthesis models, providing an indication of the production rate of even heavier antimatter nuclei and a benchmark for possible future observations of 4He in cosmic radiation.

  16. 含碳化硼的吸收和屏蔽中子辐射涂料的研究%Boron Carbide Containing Paint Absorbing and Shielding Neutron Radiation

    Institute of Scientific and Technical Information of China (English)

    黄益平; 冯惠生; 梁璐; 徐姣; 张卫江

    2011-01-01

    对碳化硼(B4C)/环氧树脂涂料合成工艺进行研究,制得一种以793树脂作为固化剂的能屏蔽和吸收中子辐射的涂料.对B4C/环氧树脂涂料的成膜条件及不同含量B4C涂料的硬度、抗冲击性、附着力和柔韧性等物理机械性能进行测试研充结果表明,含有30% B4C的环氧树脂涂料的总体机械性能最佳.在此基础上,考察了不同涂膜厚度下B4C/环氧树脂涂料的防中子辐射的性能,薄膜厚度超过300 μm时,可以有效屏蔽中子射线.%The synthesis technology of boron carbide (B4C)/epoxy resin paint was investigated, and the paint with the ability of absorbing and shielding the neutron radiation, solidified by 793 resin, was obtained. The film-forming conditions of B4C / epoxy resin paint were treated; meanwhile, the relationship between the different contents of B4C in the paint and hardness, impact resistance, adhesion, flexibility and other physical testing of mechanical properties was studied. The conclusion was obtained that the overall machinery of B4C/epoxy paint has better performance with 30% B4C. Furthermore, The anti-neutron radiation performance of B4C/epoxy paint with different film thicknesses was also examined. Results show that effective neutron radiation shielding can be achieved when the film thickness exceeds 300 nm.

  17. Proton: the particle.

    Science.gov (United States)

    Suit, Herman

    2013-11-01

    The purpose of this article is to review briefly the nature of protons: creation at the Big Bang, abundance, physical characteristics, internal components, and life span. Several particle discoveries by proton as the experimental tool are considered. Protons play important roles in science, medicine, and industry. This article was prompted by my experience in the curative treatment of cancer patients by protons and my interest in the nature of protons as particles. The latter has been stimulated by many discussions with particle physicists and reading related books and journals. Protons in our universe number ≈10(80). Protons were created at 10(-6) -1 second after the Big Bang at ≈1.37 × 10(10) years beforethe present. Proton life span has been experimentally determined to be ≥10(34) years; that is, the age of the universe is 10(-24)th of the minimum life span of a proton. The abundance of the elements is hydrogen, ≈74%; helium, ≈24%; and heavier atoms, ≈2%. Accordingly, protons are the dominant baryonic subatomic particle in the universe because ≈87% are protons. They are in each atom in our universe and thus involved in virtually every activity of matter in the visible universe, including life on our planet. Protons were discovered in 1919. In 1968, they were determined to be composed of even smaller particles, principally quarks and gluons. Protons have been the experimental tool in the discoveries of quarks (charm, bottom, and top), bosons (W(+), W(-), Z(0), and Higgs), antiprotons, and antineutrons. Industrial applications of protons are numerous and important. Additionally, protons are well appreciated in medicine for their role in radiation oncology and in magnetic resonance imaging. Protons are the dominant baryonic subatomic particle in the visible universe, comprising ≈87% of the particle mass. They are present in each atom of our universe and thus a participant in every activity involving matter.

  18. HYPOTHESIS OF THE ORIGIN OF THE UNIVERSE, SOLAR SYSTEM AND EARTH

    Directory of Open Access Journals (Sweden)

    Alexandrov B. L.

    2016-04-01

    Full Text Available It is assumed that in the primordial state of the Universe was missing the elements of matter, it was submitted to electromagnetic photon field in a broad frequency band. Photons with energy ε=1,02 born MeV electrons and positrons, and photons with energy ε=1,87 born МeV protons and antiprotons. The Association of protons, electrons and essential spectrum of photons created a sustainable hydrogen atoms and neutrons. Association of hydrogen atoms led to the creation of hydrogen clusters, and merging neutron – neutron creation of clusters (pulsars. As a result, the concentration of photons in the Universe decreased and the universe were compressed. The gravitational interactions between the hydrogen and neutron clusters was coming off of a mass of matter from both. The torn mass of hydrogen clusters were created on the planet. Separation of the mass from neutron clusters led to the neutron exposure of the main hydrogen clusters and loose parts from him (future planets. The latter, being closer to the main hydrogen accumulation, under the influence of neutron flux were redesigned to all elements of the periodic table. The article describes nuclear reactions convert one chemical element to another. After irradiation of the primary hydrogen clusters of neutrons and the emergence of the heavy and superheavy hydrogen, started fusion reactions with the release of photon energy and the transition of hydrogen clusters in Stellar condition. They began to glow. The selection of the photon energy of the Stars led to the increase in the concentration of photons in the Universe, the increase of the pressure and the expansion of the Universe, which is what happens at the present stage of its development. Combining antiprotons, electrons (positrons with the required spectrum of photons created sustainable antihydrogen and antineutrons, and their clusters – clumps of antimatter in the Universe

  19. DUSEL Theory White Paper

    Energy Technology Data Exchange (ETDEWEB)

    Raby, S.; /Ohio State U.; Walker, T.; /Ohio State U. /Ohio State U., Dept. Astron. /Ohio State U., CCAPP; Babu, K.S.; /Oklahoma State U.; Baer, H.; /Florida State U.; Balantekin, A.B.; Barger, V.; /Wisconsin U., Madison; Berezhiani, Z.; /Gran Sasso; de Gouvea, A.; /Northwestern U.; Dermisek, R.; /Princeton U.; Dolgov, A.; /Moscow, ITEP /Ferrara U.; Fileviez Perez, P.; /Wisconsin U., Madison; Gabadadze, G.; /New York U.; Gal, A.; /Hebrew U.; Gondolo, P.; /Utah U.; Haxton, W.; /Washington U., Seattle; Kamyshkov, Y.; /Tennessee U.; Kayser, B.; /Fermilab; Kearns, E.; /Boston U.; Kopeliovich, B.; /Santa Maria U., Valparaiso; Lande, K.; /Pennsylvania U.; Marfatia, D.; /Kansas U. /Maryland U. /Northeastern U. /UC, Berkeley /LBL, Berkeley /Minnesota U. /SLAC /UC, Santa Cruz /SUNY, Stony Brook /Oklahoma State U. /Iowa State U. /Carnegie Mellon U.

    2011-11-14

    The scientific case for a Deep Underground Science and Engineering Laboratory [DUSEL] located at the Homestake mine in Lead, South Dakota is exceptional. The site of this future laboratory already claims a discovery for the detection of solar neutrinos, leading to a Nobel Prize for Ray Davis. Moreover this work provided the first step to our present understanding of solar neutrino oscillations and a chink in the armor of the Standard Model of particle physics. We now know, from several experiments located in deep underground experimental laboratories around the world, that neutrinos have mass and even more importantly this mass appears to fit into the framework of theories which unify all the known forces of nature, i.e. the strong, weak, electromagnetic and gravitational. Similarly, DUSEL can forge forward in the discovery of new realms of nature, housing six fundamental experiments that will test the frontiers of our knowledge: (1) Searching for nucleon decay (the decay of protons and neutrons predicted by grand unified theories of nature); (2) Searching for neutrino oscillations and CP violation by detecting neutrinos produced at a neutrino source (possibly located at Brookhaven National Laboratory and/or Fermi National Laboratory); (3) Searching for astrophysical neutrinos originating from the sun, from cosmic rays hitting the upper atmosphere or from other astrophysical sources, such a supernovae; (4) Searching for dark matter particles (the type of matter which does not interact electromagnetically, yet provides 24% of the mass of the Universe); (5) Looking for the rare process known as neutrino-less double beta decay which is predicted by most theories of neutrino mass and allows two neutrons in a nucleus to spontaneously change into two protons and two electrons; and (6) Searching for the rare process of neutron- anti-neutron oscillations, which would establish violation of baryon number symmetry. A large megaton water Cherenkov detector for neutrinos and

  20. BLV-2011 Workshop, September 22-24, 2011

    Energy Technology Data Exchange (ETDEWEB)

    Y. A. Kamyshkov (University of Tennessee) co-Chair of the Workshop Organizing Committee; P. Fileviez Perez (University of Wisconsin) co-Chair of the Workshop Organizing Committee; W. M. Snow (Indiana University), member of Workshop Organizing Committee; A.R. Young (North Carolina State University), member of Workshop Organizing Committee

    2011-09-24

    ’L) violation, as a probe of unification, baryo- and lepto-genesis, Left-Right symmetry restoration, matter-antimatter asymmetry, sterile matter, mirror matter, dark matter, low-scale gravity, etc. Related experimental observations to these physics aspects included searches for Majorana neutrinos (2β0ν decays), proton decays, neutron-antineutron oscillations, μ-e transitions, mirror and sterile matter transformations, and possible other new phenomena that can be seen at LHC and future colliders. Combination of theoretical and experimental discussions at the Workshop was most stimulating for germinating of new theoretical ideas and promoting new experimental efforts in particle physics. As one of new developments stemmed from this Workshop was an idea of performing new neutron-antineutron transformation search at the Project X accelerator to be built at Fermilab. BLV2011 Workshop website: http://www.phys.utk.edu/BLV2011/ contains all the talks delivered at this Workshop. Agenda of the Workshop can be found in Appendix 2 to this report. During the Workshop all presentation talks were available at the web in parallel with the talks. This made the discussions of the new ideas and results at the meeting more prompt and efficient. Previous Workshops on Baryon and Lepton Number Violation search in 2007 at LBL and 2009 at the University of Wisconsin were organized essentially by the same initiative group of people as this Workshop. We are observing increased interest in the community to this physics topic. Next BLV-2013 Workshop now at bi-annual basis is being organized at the Max Plank Institute at Heidelberg by Pavel Fileviez Perez.

  1. Grands principes de symétrie à l'épreuve de l'expérience

    Science.gov (United States)

    Depommier, P.

    interesting observable seems to be the electric dipole moment of the neutron, which vanishes under time-reversal invariance (assuming parity violation). The magnitude of the theoretical predictions varies considerably, therefore the electric dipole moment of the neutron constitutes a very valuable test of time-reversal invariance. The conservation of parity and time reversal in the strong interaction raises a delicate problem in Quantum Chromodynamics. In order to get rid of parity and time reversal violating terms in the QCD Lagrangian one invokes a new symmetry which introduces a light pseudoscalar particle, the axion. This particle has been searched for but not found. Recent findings in heavy-ion collisions (the famous e+ -e- pairs) have probably nothing to do with axions. Chapter 7 deals with baryon number nonconservation. Grand unification theories have been introduced to cure several deficiencies of the Standard Model. One of the most dramatic consequences of these theories is the violation of baryon number conservation, resulting in the instability of the nucleon and other effects like neutron-antineutron oscillations. The economical model based on the unification group SU(5) fails in the prediction of the proton lifetime. Alternative unification groups have been proposed. Proton decay and neutron-antineutron searches are fundamental experiments which are pushed very strongly with a variety of experimental techniques. Lepton number nonconservation is the subject of chapter 8. The search for nuclear neutrinoless double beta decay is another activity which has become important in the attempt to elucidate the nature of the neutrino. Neutrinoless double beta decay can only occur with Majorana neutrinos if these neutrinos are massive and/or weak currents are not exactly V — A. In the context of the gauge theories the observation of this process would be a proof of massive Majorana neutrinos. Various isotopes can be used to search for double beta decay (with or without