The Large Hadron Collider forward (LHCf) experiment is designed to use the LHC to verify the hadronic-interaction models used in cosmic-ray physics. Forward baryon production is one of the crucial ...points to understand the development of cosmic-ray showers. We report the neutron-energy spectra for LHC s=7 TeV proton–proton collisions with the pseudo-rapidity η ranging from 8.81 to 8.99, from 8.99 to 9.22, and from 10.76 to infinity. The measured energy spectra obtained from the two independent calorimeters of Arm1 and Arm2 show the same characteristic feature before unfolding the detector responses. We unfolded the measured spectra by using the multidimensional unfolding method based on Bayesian theory, and the unfolded spectra were compared with current hadronic-interaction models. The QGSJET II-03 model predicts a high neutron production rate at the highest pseudo-rapidity range similar to our results, and the DPMJET 3.04 model describes our results well at the lower pseudo-rapidity ranges. However, no model perfectly explains the experimental results over the entire pseudo-rapidity range. The experimental data indicate a more abundant neutron production rate relative to the photon production than any model predictions studied here.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The differential cross sections for inclusive neutral pions as a function of transverse and longitudinal momentum in the very forward-rapidity region have been measured at the LHC with the LHC ...forward detector in proton-proton collisions at sradical=2.76 and 7 TeV and in proton-lead collisions at nucleon-nucleon center-of-mass energies of super()sNNradical=5.02TeV. Such differential cross sections in proton-proton collisions are compatible with the hypotheses of limiting fragmentation and Feynman scaling. Comparing proton-proton with proton-lead collisions, we find a sizable suppression of the production of neutral pions in the differential cross sections after subtraction of ultraperipheral proton-lead collisions. This suppression corresponds to the nuclear modification factor value of about 0.1-0.3. The experimental measurements presented in this paper provide a benchmark for the hadronic interaction Monte Carlo simulation codes that are used for the simulation of cosmic ray air showers.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
We describe reductive dehydrogenative cyclizations that form hepta-, nona-, and decacyclic anionic graphene subunits from mono- and bis-helicenes with an embedded five-membered ring. The reaction of ...bis-helicenes can either proceed to the full double annulation or be interrupted by addition of molecular oxygen at an intermediate stage. The regioselectivity of the interrupted cyclization cascade for bis-helicenes confirms that relief of antiaromaticity is a dominant force for these facile ring closures. Computational analysis reveals the unique role of the preexisting negatively charged cyclopentadienyl moiety in directing the second negative charge at a specific remote location and, thus, creating a localized antiaromatic region. This region is the hotspot that promotes the initial cyclization. Computational studies, including MO analysis, molecular electrostatic potential maps, and NICS(1.7)ZZ calculations, evaluate the interplay of the various effects including charge delocalization, helicene strain release, and antiaromaticity. The role of antiaromaticity relief is further supported by efficient reductive closure of the less strained monohelicenes where the relief of antiaromaticity promotes the cyclization even when the strain is substantially reduced. The latter finding significantly expands the scope of this reductive alternative to the Scholl ring closure.
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IJS, KILJ, NUK, PNG, UL, UM
The Large Hadron Collider forward (LHCf) experiment has been designed to use the LHC to benchmark the hadronic interaction models used in cosmic-ray physics. It measures neutral particles emitted in ...the very forward region of the LHC p-p or p-N collisions. In this paper, the performances of the LHCf detectors for hadronic showers was studied with MC simulations and beam tests. The detection efficiency for neutrons varies from 70% to 80% above 500 GeV. The energy resolutions are about 40% and the position resolution is 0.1 to 1.3mm depending on the incident energy for neutrons. The energy scale determined by the MC simulations and the validity of the MC simulations were examined using 350GeV proton beams at the CERN-SPS.
Although Bu3Sn-mediated radical alkyne peri-annulations allow access to phenalenyl ring systems, the oxidative termination of these cascades provides only a limited selection of the possible isomeric ...phenalenone products with product selectivity controlled by the intrinsic properties of the new cyclic systems. In this work, we report an oxidant-free termination strategy that can overcome this limitation and enable selective access to the full set of isomerically functionalized phenalenones. The key to preferential termination is the preinstallation of a “weak link” that undergoes C–O fragmentation in the final cascade step. Breaking a C–O bond is assisted by entropy, gain of conjugation in the product, and release of stabilized radical fragments. This strategy is expanded to radical exo-dig cyclization cascades of oligoalkynes, which provide access to isomeric π-extended phenalenones. Conveniently, these cascades introduce functionalities (i.e., Bu3Sn and iodide moieties) amenable to further cross-coupling reactions. Consequently, a variety of polyaromatic diones, which could serve as phenalenyl-based open-shell precursors, can be synthesized.
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IJS, KILJ, NUK, PNG, UL, UM
In the present paper, a biosensor is proposed with a split gate dielectric modulated bottom gate top contact organic thin‐film transistor. A cavity is marked below gate metal for enhancing ...sensitivity in biomedical applications. The organic thin‐film transistors‐based biosensors have shown applications over advanced biosensing platforms due to their intrinsic ability to transfer and amplify received biological signals into respective electrical signals. Immobilizing the biomolecules inside the cavity generates changes in surface potential. The analysis is carried out via different performance metrics that directly affect device electrical characteristics such as a change in spacer length applied voltages (Vgs and Vds) as well as channel material. After modeling, the device output characteristics are compared corresponding to simulated outcomes that validated our results. The proposed model structure is categorized by dividing it into different sections. Each categorized section's surface potential is further evaluated via 1‐ and 2‐dimensional Poisson's equation. The simulations to recreate biomolecules in terms of dielectric constant and charge density are done in the Silvaco ATLAS tool. The maximum value of sensitivity of proposed biosensor is around 300 in the case of charged biomolecule detection.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The LHCf experiment is one of the LHC forward experiments. The aim is to measure the energy and the transverse momentum spectra of photons, neutrons and pi 0 's at the very forward region (the ...pseudo-rapidity range of h > 8.4), which should be critical data to calibrate hadron interaction models used in the air shower simulations. LHCf successfully operated at s = 900 GeV and s = 7 TeV proton-proton collisions in 2009 and 2010. We present the first physics result, single photon energy spectra at s = 7 TeV proton-proton collisions and the pseudo-rapidity ranges of h > 10.94 and 8.81 < h < 8.9 . The obtained spectra were compared with the predictions by several hadron interaction models and the models do not reproduce the experimental results perfectly.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
10.
LHCf Experiment: Physics Results Bongi, M.; Adriani, O.; Berti, E. ...
Nuclear and particle physics proceedings,
10/2016, Volume:
279-281
Journal Article
Peer reviewed
LHCf is an experiment designed to study the forward emission of neutral particles produced in proton-proton and proton-nucleus collisions at the LHC. The detectors consists of a pair of ...electromagnetic sampling calorimeters installed on both sides of the ATLAS interaction point IP1 at a distance of 140 m, covering the pseudorapidity range from 8.4 to infinity. The experiment has successfully measured the energy spectra of gamma rays, neutral pions and neutrons in p-p collisions at 0.9 TeV and 7 TeV, and of neutral pions in p-Pb collisions at 5.02 TeV and in p-p collisions at 2.76 TeV. The most recent data set has been acquired during a special physics run of p-p collisions at 13 TeV in June 2015 after the restart of the LHC. This set of measurements represent an useful contribution to the calibration and tuning of the hadronic interaction models used for the simulation of atmospheric showers induced by very-high energy cosmic rays, as the measured energy interval corresponds to the range 1014 - 1017 eV in the laboratory frame.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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