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Beam instabilities in hadron synchrotrons
Beam instabilities cover a wide range of effects in particle accelerators and they have been the subjects of intense research for several decades. As the machines performance was pushed new mechanisms were revealed and nowadays the challenge consists in studying the interplays between all these intricate phenomena, as it is very often not possible to treat the different effects separately. Furthermore, the aim of this paper is to review the main mechanisms, discussing in particular the recent developments of beam instability theories and simulations.
SU-E-J-138: On the Ion Beam Range and Dose Verification in Hadron Therapy Using Sound Waves
Purpose: Accurate range verification is of great importance to fully exploit the potential benefits of ion beam therapies. Current research efforts on this topic include the use of PET imaging of induced activity, detection of emerging prompt gamma rays or secondary particles. It has also been suggested recently to detect the ultrasound waves emitted through the ion energy absorption process. The energy absorbed in a medium is dissipated as heat, followed by thermal expansion that leads to generation of acoustic waves. By using an array of ultrasound transducers the precise spatial location of the Bragg peak can be obtained. The shape and intensity of the emitted ultrasound pulse depend on several variables including the absorbed energy and the pulse length. The main objective of this work is to understand how the ultrasound wave amplitude and shape depend on the initial ion energy and intensity. This would help guide future experiments in ionoacoustic imaging. Methods: The absorbed energy density for protons and carbon ions of different energy and field sizes were obtained using Fluka Monte Carlo code. Subsequently, the system of coupled equations for temperature and pressure is solved for different ion pulse intensities and lengths to obtain the pressure wave shape, amplitude and spectral distribution. Results: The proposed calculations show that the excited pressure wave amplitude is proportional to the absorbed energy density and for longer ion pulses inversely proportional to the ion pulse duration. It is also shown that the resulting ionoacoustic pressure distribution depends on both ion pulse duration and time between the pulses. Conclusion: The Bragg peak localization using ionoacoustic signal may eventually lead to the development of an alternative imaging method with sub-millimeter resolution. It may also open a way for in-vivo dose verification from the measured acoustic signal.
A New Boson with a Mass of 125 GeV Observed with the CMS Experiment at the Large Hadron Collider
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Estimates of Z boson and J/ψ production cross sections at the large hadron collider
We calculate the leading-order cross section for the associated production of Z and J/ψ. Processes that include associated production of electroweak bosons and heavy quarkonium can give valuable insight into the production mechanism of quarkonia. We conclude that this process is accessible by the LHC statistics.
Probing nuclei by deeply penetrating and peripherally interacting Hadron: Bridging low and high-energy processes
The search for signals of new phenomenon is an important trend in the contemporary strong interaction physics. The nuclear J/{psi} suppressions are considered as like candidates for the signals of unusual events, e.g. quark-gluon plasma. They were explained in the framework of Glauber approximation. On the contrary, we show that new experimental data on the total cross section of K{sup +}-nucleus interaction at intermediate energies cannot be described by the novel well-elaborated Glauber model. This may indicate a unique event in ground state nuclei (in-medium effect)
Preliminary results of measurements of hadronic cross sections with the CMD-3 detector at the VEPP-2000 electron–positron collider
Experiments with the CMD-3 detector at the VEPP-2000 electron–positron collider in the range of center of mass collision energies from 0.32 to 2 GeV have been performed since December 2010. The amount of accumulated data corresponds to an integrated luminosity of about 60 pb{sup -1}. The resultsof a preliminary analysis are presented for the following annihilation channels: e{sup +}e{sup -} → 3(π{sup +}π{sup -}), 2(π{sup +}π{sup -}π{sup 0}), K{sup +}K{sup -}π{sup +}π{sup -}, K{sup +}K{sup -}, pp̄, and π{sup +}π{sup -}. Since processes of electron–positron annihilation that involve the production of multihadron states proceed through several intermediate states, their analysis is necessary for the correct description of the emission-angle and invariant-mass distributions of product particles.
Energy dependence of the cross sections for the e{sup +}e{sup –} → hadrons process near the production threshold for the NN̄ pair
The energy dependence of the cross sections for the processes e{sup +}e{sup −} → π{sup +}π{sup −}π{sup 0}, K{sup +}K{sup −}, ηπ{sup +}π{sup −}, ωπ{sub 0}, and K{sup +}K{sup −}π{sup +}π{sup −} is studied near the production threshold for a nucleon–antinucleon pair. It is shown that, within the measurement errors, the cross sections in question behave smoothly in this energy region.
Hadron spectrum and infrared-finite behavior of QCD running coupling
We study the behavior of the QCD effective coupling α{sub s} in the low-energy region by exploiting the conventional meson spectrum within a relativistic quantum-field model based on analytical confinement of quarks and gluons. The spectra of quark-antiquark and two-gluon bound states are defined by using a master equation similar to the ladder Bethe-Salpeter equation. A new, independent and specific infrared-finite behavior of QCD coupling is found below energy scale ∼1 GeV. Particularly, an infrared-fixed point is extracted at α{sub s}(0) ≅ 0.757 for confinement scale Λ = 345 MeV. We provide a new analytic estimate of the lowest-state glueball mass. As applications, we also estimate masses of some intermediate and heavy mesons as well as the weak-decay constants of light mesons. By introducing only a minimal set of parameters (the quark masses m{sub f} and Λ) we obtain results in reasonable agreement with recent experimental data in a wide range of energy scale ∼0.1–10 GeV. We demonstrate that global properties of some low-energy phenomena may be explained reasonably in the framework of a simple relativistic quantum-field model if one guesses correct symmetry structure of the quark-gluon interaction in the confinement region and uses simple forms of propagators in the hadronisation regime. The model may serve a reasonable framework to describe simultaneously different sectors in low-energy particle physics.
Polarization phenomena in hadronic reactions
Predictions are made in the framework of the effective color field (ECF) model for polarization observables in p+A→ Λ-bar X, A + A → ΛX and p + Pb → pX reactions. The predictions can be checked in the polarization experiments at IHEP (SPASCHARM), JINR (NICA) and BNL (RHIC). Estimates of quark masses and anamolous chromomagnetic quark moments are given.
Probing TMDs through azimuthal distributions of pions inside a jet in hadronic collisions
The azimuthal distributions around the jet axis of leading pions produced in the jet fragmentation process in pp collisions are studied within the framework of the so-called generalized parton model. The observable leading-twist azimuthal asymmetries are estimated in kinematic configurations presently investigated at RHIC. It is shown how the main contributions coming from the Collins and Sivers effects can be disentangled. In addition, a test of the process dependence of the Sivers function is provided.
Cooling of neutron stars and hybrid stars with a stiff hadronic EoS
Within the “nuclear medium cooling” scenario of neutron stars all reliably known temperature—age data, including those of the central compact objects in the supernova remnants of Cassiopeia A and XMMU-J1732, can be comfortably explained by a set of cooling curves obtained by variation of the star mass within the range of typical observed masses. The recent measurements of the masses of the pulsars PSR J1616-2230, PSR J0348-0432 and J00737-3039B and the companion of J1756-2251 provide independent proof for the existence of neutron stars with masses in a broad range from 1.2 to 2M{sub ⊙} The values M > 2M{sub ⊙} call for sufficiently stiff equations of state for neutron star matter. We investigate the response of the set of neutron star cooling curves to a stiffening of the nuclear equation of state so that maximum masses of about 2.4M{sub ⊙} would be accessible and to a deconfinement phase transition from such stiff nuclear matter in the outer core to color superconducting quark matter in the inner core. Without a readjustment of cooling inputs the mass range required to cover all cooling data for the stiff DD2 equation of state should include masses of 2.426M{sub ⊙} for describing the fast cooling of CasA while the existence of a quark matter core accelerates the cooling so that CasA cooling data are described with a hybrid star of mass 1.674M{sub ⊙}.
Cross sections of hadronic reactions e{sup +} e{sup −} → K{sup +} K{sup −} nπ (n =1,2,3) measured with the CMD3 detector at the VEPP-2000 electron-positron collider
We analyze the data on e{sup +} e{sup −} collisions at c.m.s. energies between 0.32 and 2 GeV collected in 2011–2013 with the CMD3 detector operating at the VEPP-3 e{sup +} e{sup −} collider of the Budker Institute of Nuclear Physics. The data correspond to an integrated luminosity of nearly 60 pb{sup -1}. Preliminary results e{sup +} e{sup −} → K{sup +} K{sup −} nπ (n = 1, 2, 3) on the reactions with two charged kaons in the final state are presented, and the procedure for estimating the integrated luminosity for each energy setting is described.
Fixed target project AFTER at the LHC beams for heavy ion and hadron physics
High intensity proton and lead ion beams at the LHC collider allow one to use the beam halo by placing a fixed target or a bent crystal for beam extraction. The particle energy in this case is just half that at the RHIC collider, but the luminosity exceeds the collider luminosity many times. It is also possible to install a polarized target in the extracted beam. The project AFTER is aimed at investigation of rare processes, polarization phenomena, determination of the parameters required for analysis of cosmic rays and neutrino astrophysics, detailed investigation of quarkonia production and suppression depending on the phase transition of matter to the quark-gluon phase.
Dibaryon resonances in hadron and nuclear physics: New results
The old and new experimental studies of dibaryon resonances are reviewed, and their results are interpreted theoretically. Main emphasis is made on the research in this and related areas of relativistic nuclear physics carried out at the Joint Institute for Nuclear Research (JINR) in Dubna, starting from its foundation in mid-1950s. The dibaryon studies are shown to be pivotal for JINR together with the research in such related areas as the cumulative processes, subthreshold production of mesons, single and double pion production in NN collisions, and short-range NN correlations in nuclei.