Double Differential Spectra Research Articles

The qT and \u2206\u03d5 spectra in W and Z production at the LHC at N3LL\u2032+N2LO

The production of weak gauge bosons, W± and Z, are at the core of the LHC precision measurement program. Their transverse momentum spectra as well as their pairwise ratios are key theoretical inputs to many high-precision analyses, ranging from the W mass measurement to the determination of parton distribution functions. Owing to the different properties of the W and Z boson and the different accessible fiducial regions for their measurement, a simple one-dimensional correlation is insufficient to capture the differing vector and axial-vector dynamics of the produced lepton pair. We propose to correlate them in two observables, the transverse momentum qT of the lepton pair and its azimuthal separation ∆ϕ. Both quantities are purely transverse and therefore accessible in all three processes, either directly or by utilising the missing transverse momentum of the event. We calculate all the single-differential qT and ∆ϕ as well as the double-differential (qT, ∆ϕ) spectra for all three processes at N3LL′+N2LO accuracy, resumming small transverse momentum logarithms in the soft-collinear effective theory approach and including all singlet and non-singlet contributions. Using the double-differential cross sections we build the pairwise ratios {mathrm{mathcal{R}}}_{W^{+}/Z} , {mathrm{mathcal{R}}}_{W^{-}/Z} , and {mathrm{mathcal{R}}}_{W^{+}/{W}^{-}} and determine their uncertainties assuming fully correlated, partially correlated, and uncorrelated uncertainties in the respective numerators and denominators. In the preferred partially correlated case we find uncertainties of less than 1% in most phase space regions and up to 3% in the lowest qT region.

Measurements of pi ^pm , K^pm , p and bar{p} spectra in ^7Be+^9Be collisions at beam momenta from 19A to 150A {mathrm{Ge} mathrm{V}}!/!c with the NA61/SHINE spectrometer at the CERN SPS

The NA61/SHINE experiment at the CERN Super Proton Synchrotron (SPS) studies the onset of deconfinement in hadron matter by a scan of particle production in collisions of nuclei with various sizes at a set of energies covering the SPS energy range. This paper presents results on inclusive double-differential spectra, transverse momentum and rapidity distributions and mean multiplicities of pi ^pm , K^pm , p and bar{p} produced in the 20% most central^7Be+^9Be collisions at beam momenta of 19A, 30A, 40A, 75A and 150A {mathrm{Ge} mathrm{V}}!/!c. The energy dependence of the K^pm /pi ^pm ratios as well as of inverse slope parameters of the K^pm transverse mass distributions are close to those found in inelastic p+p reactions. The new results are compared to the world data on p+p and Pb+Pb collisions as well as to predictions of the Epos, Urqmd, Ampt, Phsd and Smash models.

Measurements of pi ^- production in ^7Be + ^9Be collisions at beam momenta from 19A to 150A,text{ GeV }!/!c in the NA61/SHINE experiment at the CERN SPS

The NA61/SHINE collaboration studies at the CERN Super Proton Synchrotron (SPS) the onset of deconfinement in hadronic matter by the measurement of particle production in collisions of nuclei with various sizes at a set of energies covering the SPS energy range. This paper presents results on inclusive double-differential spectra and mean multiplicities of pi ^{-} mesons produced in the 5% most central^7Be + ^9Be collisions at beam momenta of 19A, 30A, 40A, 75A and 150A,text{ GeV }!/!c obtained by the so-called h^- method which does not require any particle identification. The shape of the transverse mass spectra differs from the shapes measured in central Pb + Pb collisions and inelastic p+p interactions. The normalized width of the rapidity distribution decreases with increasing collision energy and is in between the results for inelastic nucleon–nucleon and central Pb + Pb collisions. The mean multiplicity of pions per wounded nucleon in central^7Be + ^9Be collisions is close to that in central Pb + Pb collisions up to 75A,text{ GeV }!/!c. However, at the top SPS energy the result lies between those for nucleon–nucleon and Pb + Pb interactions. The results are discussed in the context of predictions for the onset of deconfinement at the CERN SPS collision energies.

K^{*}(892)^0 meson production in inelastic p+p interactions at 158\xa0text{ Ge }text{ V }!/!c beam momentum measured by NA61/SHINEat the CERN SPS

The measurement of K^{*}(892)^0 resonance production via its K^{+}pi ^{-} decay mode in inelastic p+p collisions at beam momentum 158 text{ Ge }text{ V }!/!c (sqrt{s_{NN}}=17.3 text{ Ge }text{ V }) is presented. The data were recorded by the NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The template method was used to extract the K^{*}(892)^0 signal and double-differential transverse momentum and rapidity spectra were obtained. The full phase-space mean multiplicity of K^{*}(892)^0 mesons was found to be (78.44 pm 0.38 mathrm {(stat)} pm 6.0 mathrm {(sys)) cdot 10^{-3}}. The NA61/SHINEresults are compared with the Epos1.99 and Hadron Resonance Gas models as well as with world data from p+p and nucleus–nucleus collisions.

Reply to “Comment on ‘Observation of annual modulation induced by γ rays from (α,γ) reactions at the Soudan Underground Laboratory' ”

Annual modulation of $\ensuremath{\gamma}$ rays from $(\ensuremath{\alpha},\ensuremath{\gamma})$ reactions induced by the $\ensuremath{\alpha}$ activity of radon and its daughters was reported by Tiwari, Zhang, Mei, and Cushman (TZMC). While Mohr does not contest the measurements themselves, he has commented that unrealistic $(\ensuremath{\alpha},\ensuremath{\gamma})$ cross sections were used in the analysis of the $\ensuremath{\gamma}$-ray flux, and thus the $\ensuremath{\gamma}$-ray fluxes calculated by TZMC are not reliable. We demonstrate that the $(\ensuremath{\alpha},\ensuremath{\gamma})$ cross sections obtained from talys include the energy-broadened cross sections for discrete states in the high-energy tail of the spectra, which are required in order to compare with the angle-integrated and double-differential spectra obtained from a liquid scintillator detector with an energy resolution of only $\ensuremath{\approx}15%$. A comparison with varying ``elwidth'' shows that cross sections indeed are reliable within the energy region (4 to 10 MeV) reported by TZMC, especially for the dominant contribution, which is the aluminum wall of the detector. Any differences in the $(\ensuremath{\alpha},\ensuremath{\gamma})$ cross sections for $^{16}\mathrm{O}$ at the level detailed by Mohr will have negligible effect on the final flux.

Constraining level densities through quantitative correlations with cross-section data

The adopted level densities (LD) for the nuclei produced through different reaction mechanisms significantly impact the calculation of cross sections for the many reaction channels. Common LD models make simplified assumptions regarding the overall behavior of the total LD and the intrinsic spin and parity distributions of the excited states. However, very few experimental constraints are taken into account: LD at neutron separation energy coming from average resonance spacings, whenever they have been previously measured, and the sometimes subjective extrapolation of discrete levels. These, however, constrain the LD only for very specific spins, parities and excitation energies. This work aims to establish additional experimental constraints on LD through quantitative correlations between cross sections and LD. This allows for the fitting and determination of detailed structures in LD. For this we use the microscopic Hartree-Fock-Bogoliubov (HFB) LD to associate variations predicted by the model with the structure observed in double-differential spectra at low outgoing neutron energy, which is dominated by the LD input. We also use \nuc{56}{Fe} ($n,p$) as an example cross sections are extremely sensitive to LD. For comparison purposes we also perform calculations with the GC model. With this approach we are able to perform fits of the LD based on actual experimental data, constraining the model and ensuring its consistency. This approach can be particularly useful in extrapolating the LD to nuclei for which high-excited discrete levels and/or resonance spacings are unknown. It also predicts inelastic gamma cross sections that can significantly differ from more standard phenomenological LD.

Measurement of phi meson production in p + p interactions at 40, 80 and 158 , hbox {GeV}/c with the NA61/SHINE spectrometer at the CERN SPS

Results on phi meson production in inelastic p + p collisions at CERN SPS energies are presented. They are derived from data collected by the NA61/SHINE fixed target experiment, by means of invariant mass spectra fits in the phi rightarrow K^+ K^- decay channel. They include the first ever measured double differential spectra of phi mesons as a function of rapidity y and transverse momentum p_{text {T}} for proton beam momenta of 80 , hbox {GeV}/c and 158 , hbox {GeV}/c, as well as single differential spectra of y or p_{text {T}} for beam momentum of 40 , hbox {GeV}/c. The corresponding total phi yields per inelastic p + p event are obtained. These results are compared with existing data on phi meson production in p + p collisions. The comparison shows consistency but superior accuracy of the present measurements. The emission of phi mesons in p + p reactions is confronted with that occurring in mathrm{Pb} + mathrm{Pb} collisions, and the experimental results are compared with model predictions. It appears that none of the considered models can properly describe all the experimental observations.

Measurement of the energy spectra and of the angular distribution of the Transition Radiation with a silicon strip detector

We plan to develop an advanced Transition Radiation Detector (TRD) for hadron identification in the TeV momentum range, based on the simultaneous measurement of the energies and of the emission angles of the Transition Radiation (TR) X-rays with respect to the radiating particles. To study the feasibility of this project, we have carried out a beam test campaign at the CERN SPS facility with 20 GeV/c electrons and muons up to 300 GeV/c. To detect the TR X-rays and the radiating particles, we used a 300 μm thick double-sided silicon strip detector, with a strip readout pitch of 50 μm. A 2 m long helium pipe was placed between the radiators and the detector, in order to ensure adequate separation between the TR X-rays and the radiating particle on the detector plane and to limit the X-ray absorption before the detector. We measured the double-differential (in energy and angle) spectra of the TR emitted by several radiators. The results are in good agreement with the predictions obtained from the TR theory.

Identification of particles with Lorentz factor up to [formula omitted] with Transition Radiation Detectors based on micro-strip silicon detectors

This work is dedicated to the study of a technique for hadron identification in the TeV momentum range, based on the simultaneous measurement of the energies and of the emission angles of the Transition Radiation (TR) X-rays with respect to the radiating particles. A detector setup has been built and tested with particles in a wide range of Lorentz factors (from about 103 to about 4×104 crossing different types of radiators. The measured double-differential (in energy and angle) spectra of the TR photons are in a reasonably good agreement with TR simulation predictions.

An intranuclear cascade model for inelastic scattering and breakup reactions involving deuterons and alpha particles

ABSTRACT The intranuclear cascade model is extended to cluster-induced (deuteron and alpha particle) nuclear reactions involving inelastic scattering and breakup reactions. The proposed model explains the projectile breakup process by describing the projectile cluster as a superposition of several states. The incident cluster and the produced cluster are assumed to be collections of independent particles and may undergo nuclear interaction through nucleon–nucleon interaction with the target nucleus. Trajectory deflections for the projectile and ejecta are incorporated in the model to account for angular distributions. Calculations with the proposed model followed by the generalized evaporation model are performed for validation by comparing with experimental double-differential cross-section spectra produced by bombarding an 27Al target separately with 80-MeV and 99.6-MeV deuterons and 140-MeV alpha particles. The calculation results show good agreement with experimental spectra.

Studying the ejection of light charged particles induced by 50 MeV 3He ions upon interacting with a 112Sn nucleus

Experimental double-differential and integral spectra of (3He, xp), (3He, xd), (3He, xt), (3He, x3He) and (3He, xα) reactions on 112Sn nuclei induced by 50 MeV 3He ions are presented. Theoretical calculations of the experimental inclusive spectra of the reactions are performed using the exciton model of preequilibrium decay. The corresponding mechanisms of reactions are determined. The experimental results can be used to develop new approaches in the theory of nuclear reactions, and to design safe and wasteless hybrid nuclear power plants.

Using the Tsallis distribution for hadron spectra in pp collisions: Pions and quarkonia at s=5−13000 GeV

A thermal model, based on the Tsallis distribution and blast-wave model, is proposed to compute hadron double-differential spectra $d^{2}N/dp_{T}dy$ in $pp$ (also high energy $p\overline{p}$) collisions. It successfully describes the available experimental data on pion and quarkonia ($\phi$, $J/\psi$, $\psi(2S)$, $\Upsilon$ family) production at energies from $\sqrt{s} = 5$ GeV to the LHC ones. Simple parametrizations for the $\sqrt{s}$ dependence of the model parameters are provided allowing predictions for the yields of these particles at new collision energies. The model can be used also for the pion Bose-Einstein correlation studies.

New56Fe Evaluation for the CIELO project

The Collaborative International Evaluated Library Organisation (CIELO) aims to provide revised and updated evaluations for Pu-239, U-238,U-235, Fe-56, O-16, and H-1 through international collaboration. This work, which is part of the CIELO project, presents the initial results for the evaluation of the Fe-56 isotope, with neutron-incident energy ranging from 0 to 20 MeV. The Fe-56(n,p) cross sections were fitted to reproduce the ones from IRDFF dosimetry file. Our preliminary file provides good cross-section agreements for the main angle-integrated reactions, as well as a reasonable overall agreement for angular distributions and double-differential spectra, when compared to previous evaluations.

QGSM development for spallation reactions modeling

The growing interest in spallation neutron sources, accelerator-driven systems, R&D of rare isotope beams, and development of external beam radiation therapy necessitated the improvement of nuclear reaction models for both stand-alone codes for the analysis of nuclear reactions and event generators within the Monte Carlo transport systems for calculations of interactions of high-energy particles with matter in a wide range of energy and in arbitrary 3D geometry of multicomponent targets. The exclusive approach to the description of nuclear reactions is the most effective for detailed calculation of inelastic interactions with atomic nuclei. It provides the correct description of particle production, single- and double-differential spectra, recoil, and fission product yields. This approach has been realized in the Quark Gluon String Model (QGSM) for nuclear reactions induced by photons, hadrons, and high energy heavy ions. In this article, improved versions of the QGSM model and a corresponding code have been developed tested and bench marked against experimental data for neutron production in spallation reactions on thin and thick targets in the energy range from a few MeV to several GeV/nucleon.

Comparison of experimental data with predictions of various models for silicon and aluminum fragmentation under the effect of high-energy cosmic rays

The accuracy attained in theoretically estimating the yields of isotopes and isobars and their energy, charge, and mass distributions in silicon fragmentation that occurs in spacecraft electronics under the effect of cosmic-ray protons is an important factor in forecasting the probability for single-event upsets in the electronics and the reliability of spacecraft operation in general. In previous studies of our group, it was shown that the results of the calculations are highly sensitive to the choice of parameters for opticalmodel potentials. In addition to cross sections for elastic and inelastic proton scattering and charge, mass, and energy distributions of heavy nuclear-reaction products, the results of our calculations for doubledifferential spectra of protons originating from the interaction of highly energetic (30–400 MeV) protons with aluminum and double-differential spectra of other particles (neutrons and alpha particles) arising in competing channels of the p + 27Al reaction are also described in the present article. The calculations in question were performed on the basis of the EMPIRE-II-19 code by using various optical-model potentials, including the Becchetti-Greenlees potential for the (p, n) channel, the Wilmore-Hodgson potential for the (p, n) channel, the Madland potential for the (p, p) channel, the Koning-Delaroche potential for the (p, p) channel, and the McFadden-Satchler potential for the (p, α) channel. A comparative analysis of the double-differential spectra obtained for outgoing protons, neutrons, and alpha particles experimentally and in the calculations of various authors was performed.

PRE-EQUILIBRIUM ALPHA-PARTICLE EMISSION AS A PROBE TO EXPLORE ALPHA CLUSTERING IN NUCLEI

Experimental data of the double-differential spectra of light particles emitted at pre-equilibrium stage of nuclear processes were obtained at Laboratori Nazionali di Legnaro for the heavy-ion reactions 130 and 250 MeV 16 O + 116 Sn . Light charged particles were measured in coincidence with evaporation residues in order to avoid unwanted competing mechanisms. The experimental data were collected in a wide angular range from 29 to 82 degrees in the laboratory system. Theoretical model was developed in order to describe simultaneously evaporative and pre-equilibrium emission of the light particles in heavy-ion reactions. Griffin exciton model was used for the description of the pre-equilibrium stage of the compound nucleus formation, while the equilibrium evaporation processes were analyzed in the framework of the statistical theory of heavy-ion reactions. Experimental data were compared with the results of the model calculations and new approach was suggested to take into account alpha cluster formation in the projectile nucleus by measuring and analyzing pre-equilibrium alpha-particle spectra.

Double-differential spectra of the secondary particles in the frame of pre-equilibrium model

An approach was developed to describe the double-differential spectra of secondary particles formed in heavy-ion reactions. Griffin model of nonequilibrium processes was used to account for the nonequilibrium stage of the compound system formation. Simulation of de-excitation of the compound system was carried out using the Monte-Carlo method. Analysis of the probability of neutron, proton, and α-particle emission was performed both in equilibrium, and in the pre-equilibrium stages of the process. Fission and γ-ray emission were also considered after equilibration. The analysis of the experimental data on the double-differential cross sections of p, α particles for the 16O + 116Sn reaction at the oxygen energy E = 130 and 250 MeV were performed.

A Distorted Wave model for electron ionization in collisions between clothed-ions and atomic targets

In the present work we extend the Continuum Distorted Wave – Eikonal Initial State (CDW-EIS) model to the case of dressed projectiles. Double differential spectra are analyzed for single ionization of He atoms in collisions with U21+ ions as a function of the final energy and angle of the emitted electron. Structures interpreted in terms of coherent interference of short- and long-range contributions of the perturbative projectile potential are observed.

Double-differential spectra of secondary particles from hadrons on tissue equivalent targets

Double-differential spectra generated by ions on tissue equivalent targets were calculated with the FLUKA code. Seven different species of ion beams were simulated, impinging onto an ICRU tissue equivalent target representing the chest of a patient under treatment. The following ion beams were investigated at an energy level capable of penetrating ICRU tissue up to a 26.2 cm depth: H, He, Li, B, C, N and O at 200.0, 202.0, 234.3, 329.5, 390.7, 430.5 and 468.0 MeV u(-1), respectively. The double-differential spectra of secondary neutrons, protons, photons, positive and negative pions, electrons and positrons were scored over the entire solid angle. Curve-fitting of the calculated data is also given.

Secondary Neutron-Production Cross Sections from Heavy-Ion Interactions between 230 and 600 MeV/Nucleon

Secondary neutron-production cross sections have been measured from interactions of 230 MeV/nucleon He, 400 MeV/nucleon N, 400 MeV/nucleon Kr, 400 MeV/nucleon Xe, 500 MeV/nucleon Fe, and 600 MeV/nucleon Ne interacting in a variety of elemental and composite targets. We report the double-differential production cross sections, angular distributions, energy spectra, and total cross sections from all systems. Neutron energies were measured using the time-of-flight technique and were measured at laboratory angles between 5 and 80 deg. The spectra exhibit behavior previously reported in other heavy-ion-induced neutron-production experiments, namely, a peak at forward angles near the energy corresponding to the beam velocity, with the remaining spectra generated by preequilibrium and equilibrium processes. The double-differential spectra are fitted with a moving-source parameterization. Observations on the dependence of the total cross sections on target and projectile mass are discussed.