Development of organic scintillators

Abstract We present the first results of a measurement of the total cross-section σ T in proton-proton collisions at equivalent laboratory momenta between 291 and 1480 GeV/ c at the CERN Intersecting Storage Rings (ISR). The method is based on the measurement of the ratio of the total interaction rate and the machine luminosity. The data show an increase of about 10% in σ T in this energy interval.

Measurement of the Total Proton-Proton Cross Section at the ISR. (Abstract)

We present a new version of the hadron interaction event generator sibyll. While the core ideas of the model have been preserved, the new version handles the production of baryon pairs and leading particles in a new way. In addition, production of charmed hadrons is included. Updates to the model are informed by high-precision measurements of the total and inelastic cross sections with the forward detectors at the LHC that constrain the extrapolation to ultrahigh energy. Minimum-bias measurements of particle spectra and multiplicities support the tuning of fragmentation parameters. This paper demonstrates the impact of these changes on air-shower observables such as ${X}_{\mathrm{max}}$ and ${N}_{\ensuremath{\mu}}$, drawing comparisons with other contemporary cosmic-ray interaction models.

Hadronic interaction model sibyll 2.3d and extensive air showers

The cosmic ray composition between 1014 and 1016 eV

Using a prototype of a large hadron calorimeter, vertical cosmic ray hadrons were recorded and the all-hadron flux was measured in the range from 5 GeV to 10 TeV. Hadron reconstruction and identification are described. We observe a vertical flux of dI/dEh=(1.59+or-0.24)*10-5(Eh/100 GeV)-2.72+or-0.10 (m2 s sr GeV)-1. The flux compares well with values obtained in other experiments. Total inelastic cross sections for protons scattered by nuclei in air are deduced from the unaccompanied hadron flux and compared with the values reported by other authors.

Cosmic ray hadron flux at sea level up to 15 TeV

An experimental study of the distribution of arrival time of energetic hadrons relative to associated air-shower particles has been made at a mountain altitude, under 730 g ${\mathrm{cm}}^{\ensuremath{-}2}$. Monte Carlo simulations have shown that these observations are sensitive to the composition of primary cosmic rays of energies ${10}^{4}$-${10}^{6}$ GeV. The energy spectra $\frac{\mathrm{dN}}{\mathrm{dE}}$ of primary protons and iron-group nuclei required to understand these observations are $1.5\ifmmode\times\else\texttimes\fi{}{10}^{4}{E}^{\ensuremath{-}2.71\ifmmode\pm\else\textpm\fi{}0.06}$ and $1.27{E}^{\ensuremath{-}2.36\ifmmode\pm\else\textpm\fi{}0.06}$ ${\mathrm{m}}^{\ensuremath{-}2}$ ${\mathrm{sr}}^{\ensuremath{-}1}$ ${\mathrm{sec}}^{\ensuremath{-}1}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{N})}^{\ensuremath{-}1}$, respectively, where $E$ is the energy per nucleon.

Composition of Primary Cosmic Rays above 10 13 eV from the Study of Time Distributions of Energetic Hadrons near Air-Shower Cores

The energy spectrum of unaccompanied hadrons has been measured at a depth of 730 g cm-2 in the atmosphere. The energy was determined by a deep calorimeter (960 g cm-2) of area 4 m2. For charged hadrons unaccompanied in a 3.3 m2 spark chamber placed above the calorimeter, the observed flux was fitted in the energy range 100<E<10000 GeV.

http://iopscience.iop.org/article/10.1088/0305-4616/4/7/021/pdf

Unaccompanied hadron flux at a depth of 730 g cm-2, 102<E<104 GeV

The distribution of arrival time of energetic hadrons in the near-core region of air showers of energies \ensuremath{\sim}${10}^{4}$-${10}^{6}$ GeV relative to the shower front has been studied experimentally at mountain altitude. The observed rate of hadron events with (i) energy g50 GeV in the calorimeter, (ii) associated shower particle density g18 ${\mathrm{m}}^{\ensuremath{-}2}$, and (iii) a signal \ensuremath{\ge}5 equivalent particles in a plastic scintillator ${T}_{3}$ of area 0.54 ${\mathrm{m}}^{2}$ placed under 220 g ${\mathrm{cm}}^{\ensuremath{-}2}$ of absorber in the calorimeter is found to be 1.85\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$ ${\mathrm{m}}^{\ensuremath{-}2}$${\mathrm{sr}}^{\ensuremath{-}1}$${\mathrm{sec}}^{\ensuremath{-}1}$. Of these events a fraction (0.55\ifmmode\pm\else\textpm\fi{}0.05)% have shown the signal from ${T}_{3}$ to be delayed by 15 nsec or greater relative to shower particles. Monte Carlo simulations of experimental observations have shown that these requirements on energy and shower density enhance the sensitivity of the observed rate to the contributions due to showers initiated by heavy nuclei. Calculations also show that observed delayed hadrons are mostly associated with showers due to heavy nuclei. For interpretation of observed features two models for primary composition have been considered. In the first model the power-law spectra for protons and lighter nuclei are assumed to have spectral index ${\ensuremath{\gamma}}_{p}$ and the heavy (iron group) nuclei the index ${\ensuremath{\gamma}}_{\mathrm{Fe}}$. An agreement between the expectation and observation requires the values of ${\ensuremath{\gamma}}_{p}$ and ${\ensuremath{\gamma}}_{\mathrm{Fe}}$ to be significantly different as -2.68 and -2.39 in the energy range \ensuremath{\sim}${10}^{3}$-${10}^{6}$ GeV. In the second model the spectral index $\ensuremath{\gamma}$ is assumed to be the same for all components and the spectra steepen by 0.5 at the same rigidity ${R}_{c}$. It is found that the values of $\ensuremath{\gamma}$ and ${R}_{c}$ should be -2.55 and ${10}^{5}$ GV/c, respectively, to match the observations. It is concluded that a successful understanding of experimental observations requires a relative change between the energy spectra of protons and heavy nuclei in the energy range \ensuremath{\sim}${10}^{4}$-${10}^{6}$ GeV, which would make the proportion of iron-group nuclei about 40% of the primary flux at these energies.

Delayed hadrons in extensive air showers: Evidence for the iron-group nuclei in primary cosmic-ray flux at energies ∠10 13 -10 15 eV

The steepening of the proton spectrum beyond 1000 GeV and the rise in inelastic cross sections between 20 and 600 GeV observed by the PROTON-1-2-3 satellite experiments were explained by systematic effects of energy dependent albedo (backscatter) from the calorimeter.

/pdf/on-the-high-energy-proton-spectrum-measurements-43riebk084.pdf

On the high energy proton spectrum measurements

The flux of charged hadrons has been measured at sea level with an iron calorimeter of depth 960 g cm-2; the geometric factor was about 0.7 m2 sr. The total running time was 1.6*106 s. An upper limit to the flux of all hadrons has been obtained in the energy range 500<E<10000 GeV. It does not support the observation of a 'step' in the spectrum at about 3000 GeV.

F. Siohan

Papers

Composition of Primary Cosmic Rays above 10 13 eV from the Study of Time Distributions of Energetic Hadrons near Air-Shower Cores

Unaccompanied hadron flux at a depth of 730 g cm-2, 102<E<104 GeV

Delayed hadrons in extensive air showers: Evidence for the iron-group nuclei in primary cosmic-ray flux at energies ∠10 13 -10 15 eV

On the high energy proton spectrum measurements

Measurement of the flux of charged hadrons at sea level between 250 and 10000 GeV