Hadronic Particle Research Articles

Optimization Of Robust Beam Angles To Patient Setup Errors For Head and Neck Cancer In Hadron Particle Therapy

In hadron particle therapy, precise depth dose distribution around the target tumor can be produced by using a compensator in a depth dose shaping system, which is produced based on lateral and distal distributions in electron density of each patient's computed tomography image. However, the precise dose distribution fitted with a tumor shape could be fragile for slight misalignment between the compensator and the tumor, especially if the abrupt lateral distribution of the electron density projection (e.g.

A contribution to the identification of the E5 defect level as tri-vacancy (V3)

Silicon particle detectors in tracking devices for the high luminosity Large Hadron Collider will suffer from an extremely intense radiation field of mainly hadronic particles. The main radiation induced deep defect centres in silicon, responsible for the increase of the dark current and corresponding noise, are the cluster related defect levels E5 and E205a. This work confirms the identification of the E5 level as tri-vacancy (V3). This defect transforms into the tri-vacancy-oxygen complex (V3O) at temperatures above 200°C. The defect concentrations were obtained by means of Deep Level Transient Spectroscopy (DLTS) and Thermally Stimulated Current technique (TSC) performed on float zone (FZ), epitaxially grown (Epi) and Magnetic Czochralski (MCz) silicon diodes, irradiated with 1MeV neutrons and 23GeV protons.

Physics program of P̄ANDA experiment at FAIR

The “antiProton ANnihilation at DArmstadt”-experiment, P̄ANDA, is one of the main experiments at FAIR, the future Facility for Anti-proton and Ion Research at GSI, Darmstadt. It will be using the antiproton beam of unprecedented intensity and high momentum resolution in the momentum range between 1.5 – 15 GeV/c which will be available at the High Energy Storage Ring (HESR) at FAIR. The P̄ANDA experiment aims at high precision spectroscopy in order to address the properties of the strong interaction. The major physics research topics are: hadron spectroscopy, in-medium effects of hadronic particles, study of nucleon structure and precision gamma-ray spectroscopy of single- and double-Λ hypernuclei. To meet the physics objectives of P̄ANDA, a detector with a nearly complete solid angle coverage, an excellent particle identification of hadrons and leptons over a large momentum range and high resolution calorimetry for neutral particles is essential. An overview of the goals and the extensive physics programs, detector development as well as simulation aspects of the P̄ANDA experiment will be discussed.

Hadronic Particles made of Multi-ρ(770) Mesons

We present a work (Roca and Oset in Phys. Rev. D 82, 054013, 2010) where we use the ρ ρ interaction in spin 2 and isospin 0 channel to show that the resonances ρ 3(1690)(3−−), f 4(2050)(4++), ρ 5(2350)(5−−) and f 6(2510)(6++) can be interpreted as few body systems made of an increasing number of ρ(770) particles. We use the fixed center approximation of the Faddeev equations to write the multi-body interaction in terms of the two-body scattering amplitudes. Very good agreement with the experimental masses is found.

Kinematics of τ two-body decay near τ threshold at BESIII

The kinematic properties of two-body decay near τ threshold are studied according to the special capacity of the BEPC II accelerator and the BESIII detector. Explicitly presented are the transformations of energy and momentum of hadronic particles between different reference frames, and the corresponding distributions. A brand new method is proposed to obtain the energy spread of the accelerator by fitting the energy distribution of hadron from τ semi-leptonic decays.

Thermalization through Hagedorn states: the importance of multiparticle collisions

Quick chemical equilibration times of hadrons within a hadron gas are explained dynamically using Hagedorn states, which drive particles into equilibrium close to the critical temperature. Within this scheme master equations are employed for the chemical equilibration of various hadronic particles such as (strange) baryons and antibaryons. A comparison of the Hagedorn model to recent lattice results is made and it is found that for both Tc = 176 MeV and Tc = 196 MeV the hadrons can reach chemical equilibrium almost immediately, well before the chemical freeze-out temperatures found in thermal fits for a hadron gas without Hagedorn states.

Construction and performance of the BABAR-DIRC

The new type of ring-imaging Cherenkov detector technology called DIRC (an acronym for Detection of Internally Reflected Cherenkov Light) has been used successfully for hadronic particle identification in the BABAR experiment at the B Factory (PEP-II) located at the SLAC National Accelerator Laboratory. This paper describes the R&D for and the construction of the DIRC radiator bars and the performance of the DIRC during more than eight years of B Factory operation.

On the measurement of the proton-air cross section using air shower data

The analysis of high-energy air shower data allows one to study the proton-air cross section at energies beyond the reach of fixed target and collider experiments. The mean depth of the first interaction point and its fluctuations are a measure of the proton-air particle production cross section. Since the first interaction point in air cannot be measured directly, various methods have been developed in the past to estimate the depth of the first interaction from air shower observables in combination with simulations. As the simulations depend on assumptions made for hadronic particle production at energies and phase space regions not accessible in accelerator experiments, the derived cross sections are subject to significant systematic uncertainties. The focus of this work is the development of an improved analysis technique that allows a significant reduction of the model dependence of the derived cross section at very high energy. Performing a detailed Monte Carlo study of the potential and the limitations of different measurement methods, we quantify the dependence of the measured cross section on the hadronic interaction model used. Based on these results, a general improvement of the analysis methods is proposed by introducing the actually derived cross section already in the simulation of reference showers. The reduction of the model dependence is demonstrated for one of the measurement methods.

Thermal production of strange particles

Global strangeness production in elementary and relativistic heavy-ion collisions is reviewed within the framework of the statistical hadronization model. It is shown that recent RHIC data on strange particle production as a function of centrality can be explained by a superposition of a fully equilibrated hadron gas and particle emission from single independent nucleon–nucleon collisions in the outer corona. It is argued that strangeness suppression in elementary collisions with respect to a fully equilibrated hadron gas can be explained within a model where hadronization is interpreted as a hadronic Hawking–Unruh radiation.

The Main Injector Particle Production Experiment

It is currently impossible to apply the theory of strong interactions, QCD, to compute non-perturbative hadron interaction cross sections from first principles. Thus high quality hadronic particle production measurements are needed to fully understand the data from experiments that have hadronic interactions as a signal or background. This includes atmospheric and accelerator neutrino experiments, calorimetry and hadronic shower simulation. Such data can also be used to test observed regularities in particle production such as scaling relations in inclusive reactions with some precision. The spectrum of baryon resonances predicted by QCD includes many states that have not been observed. Measurements of pion, kaon, and proton beams on a liquid hydrogen target at beam momenta around 1 GeV/c will provide important input to searches for missing baryon resonances. We review status, results, and prospects of particle production measurements at Fermilab.

Parton dynamics and hadronization from the sQGP

The hadronization of an expanding partonic fireball is studied within the Parton-Hadron-String Dynamics (PHSD) approach which is based on a dynamical quasiparticle model (DQPM) matched to reproduce lattice QCD results in thermodynamic equilibrium. Apart from strong parton interactions the expansion and development of collective flow is found to be driven by strong gradients in the parton mean-fields. An analysis of the elliptic flow v 2 demonstrates a linear correlation with the spatial eccentricity ϵ as in the case of ideal hydrodynamics. The hadronization occurs by quark–antiquark fusion or 3 quark/3 antiquark recombination which is described by covariant transition rates. Since the dynamical quarks become very massive, the formed resonant ‘pre-hadronic’ color-dipole states ( q q ̄ or q q q ) are of high invariant mass, too, and sequentially decay to the groundstate meson and baryon octets increasing the total entropy. This solves the entropy problem in hadronization in a natural way. Hadronic particle ratios turn out to be in line with those from a grand-canonical partition function at temperature T ≈ 170 MeV.

Hydrodynamic radial and elliptic flow in heavy-ion collisions from AGS to LHC energies

Using ideal relativistic hydrodynamics in 2+1 dimensions, we study the collision-energy dependence of radial and elliptic flow, of the emitted hadron spectra, and of the transverse momentum dependence of several hadronic particle ratios, covering the range from Alternating Gradient Synchrotron (AGS) to Large Hadron Collider (LHC) energies. These calculations establish an ideal-fluid dynamic baseline that can be used to assess non-equilibrium features manifest in future LHC heavy-ion experiments. Contrary to earlier suggestions we find that a saturation and even decrease of the differential elliptic flow v2(pT) with increasing collision energy cannot be unambiguously associated with the QCD phase transition.

Thermodynamics for a hadronic gas of fireballs with internal color structures and chiral fields

The thermodynamic partition function for a gas of color-singlet bags consisting of fundamental and adjoint particles in both $\mathrm{U}({N}_{c})$ and $\mathrm{SU}({N}_{c})$ group representations is reviewed in detail. The constituent particle species are assumed to satisfy various thermodynamic statistics. The gas of bags is probed to study the phase transition for nuclear matter in extreme conditions. These bags are interpreted as the Hagedorn states, and they are the highly excited hadronic states produced below the phase transition point to the quark-gluon plasma (QGP). The hadronic density of states has the Gross-Witten critical point and exhibits a third-order phase transition from a hadronic phase dominated by the discrete low-lying hadronic mass spectrum particles to another hadronic phase dominated by the continuous Hagedorn states. The Hagedorn threshold production is found just above the highest known experimental discrete low-lying hadronic mass spectrum. The subsequent Hagedorn phase undergoes a first-order deconfinement phase transition to an explosive QGP. The role of the chiral phase transition in the phases of the discrete low-lying mass spectrum and the continuous Hagedorn mass spectrum is also considered. It is found to be crucial in the phase transition diagram. Alternative scenarios are briefly discussed for the Hagedorn gas undergoing a higher order phase transition through multiple processes of internal color-flavor structure modification.

Strangeness production from SPS to LHC

Global strangeness production in relativistic heavy ion collisions at SPS and RHIC is reviewed. Special emphasis is put on the comparison with the statistical model and the canonical suppression mechanism. It is shown that recent RHIC data on strange particle production as a function of centrality can be explained by a superposition of a fully equilibrated hadron gas and particle emission from single independent nucleon–nucleon collisions in the outer corona.

Advantages and limitations of the RICH technique for particle identification

The ring imaging Cherenkov (RICH) technique for hadronic particle identification (PID) is described. The advantages and limitations of RICH PID counters are compared with those of other classic PID techniques, such as threshold Cherenkov counters, ionization loss (d E/d x) in tracking devices, and time of flight (TOF) detectors.

FLUKA Monte Carlo simulation code as used for radiation studies in the Alice experiment

The main features of the FLUKA Monte Carlo code, which can deal with transport and interaction of electromagnetic and hadronic particles, are summarized. The physical models embedded in FLUKA are described. Application of the code for the radiation background calculations. Especially, the origin and composition of the intense radiation field to be expected in parts of the ALICE detector for the coming multi-TeV LHC collider is described. It is important to evaluate the risk of radiation damage in detectors and electronics equipment.

Using X‐ray observations to identify the particle acceleration mechanisms in VHE SNRs and “dark” VHE sources

AbstractVery high energy (VHE) γ‐ray observations have proven to be very successful in localizing Galactic acceleration sites of VHE particles. Observations of shell‐type supernova remnants have confirmed that particles are accelerated to VHE energies in supernova blast waves; the interpretation of the γ‐ray data in terms of hadronic or leptonic particle components in these objects relies nevertheless strongly on input from X‐ray observations. The largest identified Galactic VHE source class consists of pulsar wind nebulae, as detected in X‐rays. Many of the remaining VHE sources remain however unidentified until now. With X‐ray observations of these enigmatic “dark” objects one hopes to solve the following questions: What is the astrophysical nature of these sources? Are they predominantly electron or hadron accelerators? And what is their contribution to the overall cosmic ray energy budget? The paper aims to provide an overview over the identification status of the Galactic VHE source population. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

COST–ENLIGHT strategic workshop on hadron (particle) therapy, CERN, Geneva, 3–4 May 2007

This meeting was convened by COST (Co-operation in the Field of Scientific and Technical Research) and ENLIGHT (European Network for Research in Light-Ion Hadron Therapy) to review the current status of hadron therapy in Europe. The aims were to increase awareness of hadron therapy within the scientific community, to produce a document outlining the present and future prospects for this treatment modality and to bring together hadron therapy scientists and clinicians. Proton therapy offers the potential for therapeutic gain from dose distribution advantages when compared with photon therapy. Carbon ion therapy, by nature of its higher linear energy transfer (LET) and relative biological effectiveness (RBE), may further improve local control. A further potential benefit of carbon ion therapy is the ability to deliver hypofractionated radiotherapy. A further aim of this meeting was to commence preparation of a programme of work packages with a view to submitting an application for European Union funding within the FP7 programme. This comprises a series of seven work packages, which will be a focus for European collaboration.

Implementation of the Random Forest method for the Imaging Atmospheric Cherenkov Telescope MAGIC

The paper describes an application of the tree classification method Random Forest (RF), as used in the analysis of data from the ground-based gamma telescope MAGIC. In such telescopes, cosmic gamma-rays are observed and have to be discriminated against a dominating background of hadronic cosmic-ray particles. We describe the application of RF for this gamma/hadron separation. The RF method often shows superior performance in comparison with traditional semi-empirical techniques. Critical issues of the method and its implementation are discussed. An application of the RF method for estimation of a continuous parameter from related variables, rather than discrete classes, is also discussed.

Channel Mapping of the ZEUS Straw-Tube Tracker

The Straw-Tube Tracker (STT) is part of a global tracking system of the ZEUS detector at the e <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">plusmn</sup> p storage ring HERA at DESY in Hamburg, Germany. The STT covers in combination with other tracking detectors the forward region of the experiment 1.75<eta<2.5. The highest hadronic particle flux appears in that region within the experiment. After the final installation of the STT within the ZEUS detector, intensive checks are done in order to confirm the functionality before the first STT data taking period. A channel mapping procedure described in this paper identifies dead and unstable channels. A correlation is seen between the number of dead or unstable channels and hadronic radiation level in the detector