•The SEALION approach allows pre-determination of the temperature reactivity response.•The SEALION approach is computationally lightweight.•Serpent-OF coupling uses high accuracy Monte-Carlo ...approach.•Serpent-OF coupling does not modify the software to significant extend.
Crucial to the development of molten salt reactor (MSR) designs is the application of multiphysics codes to model the tightly coupled neutronics and thermal-hydraulics behaviour of the liquid fuel. However, the verification and validation of such codes is not a trivial task, in particular for fast reactor designs, where no experimental data are available. In absence of experimental data, a benchmark was developed by LPSC/CNRS-Grenoble for multiphysics codes dedicated to MSR studies. In this study we present two independent multiphysics approaches and apply them to this benchmark. The first approach utilizes the Serpent2 multiphysics interface, allowing for high fidelity coupling of the finite volume computational fluid dynamics code OpenFOAM and Serpent2. In this approach, Serpent2 serves as the neutronics solver and is coupled to an OpenFOAM based thermal-hydraulics solver and supplemented by a delayed neutron precursors transport solver implemented in OpenFOAM. The main advantage of this coupling approach is that it allows for using a high accuracy Monte-Carlo approach to solve the neutron transport equations. The second approach is a novel approach that utilizes the SEALION framework. The SEALION code employs a specialized thermal hydraulics solver based on OpenFOAM, coupled with a custom-made modified point kinetics neutronics solver, that explicitly accounts for the altered neutron importance due to the transport of delayed neutron precursors. The main advantage of this approach is that it allows for a pre-determination of the temperature feedback effects using Monte-Carlo codes, such as Serpent2. Both approaches are verified against results from the benchmark and the overall agreement between the results demonstrates the validity of both approaches.
Measurements of the kinematic distributions of
J
/
ψ
mesons produced in
p
–C,
p
–Ti and
p
–W collisions at
in the Feynman-
x
region −0.34<
x
F
<0.14 and for transverse momentum up to
p
T
=5.4 GeV/c ...are presented. The
x
F
and
p
T
dependencies of the nuclear suppression parameter,
α
, are also given. The results are based on 2.4×10
5
J
/
ψ
mesons reconstructed in both the
e
+
e
−
and
μ
+
μ
−
decay channels. The data have been collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The measurement explores the negative region of
x
F
for the first time. The average value of
α
in the measured
x
F
region is 0.981±0.015. The data suggest that the strong nuclear suppression of
J
/
ψ
production previously observed at high
x
F
turns into an enhancement at negative
x
F
.
The centrality dependence of the mean charged-particle multiplicity as a function of pseudorapidity is measured in approximately 1 Formula: see textbFormula: see text of proton-lead collisions at a ...nucleon-nucleon centre-of-mass energy of Formula: see text Formula: see text using the ATLAS detector at the Large Hadron Collider. Charged particles with absolute pseudorapidity less than 2.7 are reconstructed using the ATLAS pixel detector. The Formula: see text collision centrality is characterised by the total transverse energy measured in the Pb-going direction of the forward calorimeter. The charged-particle pseudorapidity distributions are found to vary strongly with centrality, with an increasing asymmetry between the proton-going and Pb-going directions as the collisions become more central. Three different estimations of the number of nucleons participating in the Formula: see text collision have been carried out using the Glauber model as well as two Glauber-Gribov inspired extensions to the Glauber model. Charged-particle multiplicities per participant pair are found to vary differently for these three models, highlighting the importance of including colour fluctuations in nucleon-nucleon collisions in the modelling of the initial state of Formula: see text collisions.
The paper presents studies of Bose-Einstein Correlations (BEC) for pairs of like-sign charged particles measured in the kinematic range Formula: see text 100 MeV and Formula: see text 2.5 in proton ...collisions at centre-of-mass energies of 0.9 and 7 TeV with the ATLAS detector at the CERN Large Hadron Collider. The integrated luminosities are approximately 7 Formula: see textbFormula: see text, 190 Formula: see textbFormula: see text and 12.4 nbFormula: see text for 0.9 TeV, 7 TeV minimum-bias and 7 TeV high-multiplicity data samples, respectively. The multiplicity dependence of the BEC parameters characterizing the correlation strength and the correlation source size are investigated for charged-particle multiplicities of up to 240. A saturation effect in the multiplicity dependence of the correlation source size parameter is observed using the high-multiplicity 7 TeV data sample. The dependence of the BEC parameters on the average transverse momentum of the particle pair is also investigated.
Double-differential three-jet production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of Formula: see text using the ATLAS detector at the large hadron collider. ...The measurements are presented as a function of the three-jet mass Formula: see text, in bins of the sum of the absolute rapidity separations between the three leading jets Formula: see text. Invariant masses extending up to 5 TeV are reached for Formula: see text. These measurements use a sample of data recorded using the ATLAS detector in 2011, which corresponds to an integrated luminosity of Formula: see text. Jets are identified using the anti-Formula: see text algorithm with two different jet radius parameters, Formula: see text and Formula: see text. The dominant uncertainty in these measurements comes from the jet energy scale. Next-to-leading-order QCD calculations corrected to account for non-perturbative effects are compared to the measurements. Good agreement is found between the data and the theoretical predictions based on most of the available sets of parton distribution functions, over the full kinematic range, covering almost seven orders of magnitude in the measured cross-section values.
A search for a massive Formula: see text gauge boson decaying to a top quark and a bottom quark is performed with the ATLAS detector in Formula: see text collisions at the LHC. The dataset was taken ...at a centre-of-mass energy of Formula: see text and corresponds to Formula: see text of integrated luminosity. This analysis is done in the hadronic decay mode of the top quark, where novel jet substructure techniques are used to identify jets from high-momentum top quarks. This allows for a search for high-mass Formula: see text bosons in the range 1.5-3.0 Formula: see text. Formula: see text-tagging is used to identify jets originating from Formula: see text-quarks. The data are consistent with Standard Model background-only expectations, and upper limits at 95 % confidence level are set on the Formula: see text cross section times branching ratio ranging from Formula: see text to Formula: see text for left-handed Formula: see text bosons, and ranging from Formula: see text to Formula: see text for Formula: see text bosons with purely right-handed couplings. Upper limits at 95 % confidence level are set on the Formula: see text-boson coupling to Formula: see text as a function of the Formula: see text mass using an effective field theory approach, which is independent of details of particular models predicting a Formula: see text boson.
We have searched for Theta+(1540) and Xi(--)(1862) pentaquark candidates in proton-induced reactions on C, Ti, and W targets at midrapidity and square root of s = 41.6 GeV. In 2 x 10(8) inelastic ...events we find no evidence for narrow (sigma approximately 5 MeV) signals in the Theta+ --> pK0(S) and Xi(--) --> Xi- pi- channels; our 95% C.L. upper limits (UL) for the inclusive production cross section times branching fraction B dsigma/dy/(y approximately 0) are (4-16) mub/N for a Theta+ mass between 1521 and 1555 MeV, and 2.5 mub/N for the Xi(--). The UL of the yield ratio of Theta+/Lambda(1520) < (3-12)% is significantly lower than model predictions. Our UL of B Xi(--)/Xi(1530)0 < 4% is at variance with the results that have provided the first evidence for the Xi(--).
The performance of the ATLAS muon trigger system is evaluated with proton-proton collision data collected in 2012 at the Large Hadron Collider at a centre-of-mass energy of 8 TeV. It is primarily ...evaluated using events containing a pair of muons from the decay of Formula: see text bosons. The efficiency of the single-muon trigger is measured for muons with transverse momentum Formula: see text GeV, with a statistical uncertainty of less than 0.01 % and a systematic uncertainty of 0.6 %. The Formula: see text range for efficiency determination is extended by using muons from decays of Formula: see text mesons, Formula: see text bosons, and top quarks. The muon trigger shows highly uniform and stable performance. The performance is compared to the prediction of a detailed simulation.
This paper presents cross sections for the production of a Formula: see text boson in association with jets, measured in proton-proton collisions at Formula: see text with the ATLAS experiment at the ...large hadron collider. With an integrated luminosity of Formula: see text, this data set allows for an exploration of a large kinematic range, including jet production up to a transverse momentum of Formula: see text and multiplicities up to seven associated jets. The production cross sections for Formula: see text bosons are measured in both the electron and muon decay channels. Differential cross sections for many observables are also presented including measurements of the jet observables such as the rapidities and the transverse momenta as well as measurements of event observables such as the scalar sums of the transverse momenta of the jets. The measurements are compared to numerous QCD predictions including next-to-leading-order perturbative calculations, resummation calculations and Monte Carlo generators.
A measurement of Formula: see text boson production in lead-lead collisions at Formula: see text is presented. It is based on the analysis of data collected with the ATLAS detector at the LHC in 2011 ...corresponding to an integrated luminosity of 0.14 Formula: see text and 0.15 Formula: see text in the muon and electron decay channels, respectively. The differential production yields and lepton charge asymmetry are each measured as a function of the average number of participating nucleons Formula: see text and absolute pseudorapidity of the charged lepton. The results are compared to predictions based on next-to-leading-order QCD calculations. These measurements are, in principle, sensitive to possible nuclear modifications to the parton distribution functions and also provide information on scaling of Formula: see text boson production in multi-nucleon systems.
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