2,388 research outputs found
Kopparrelaterad fotodegradering i kristallint kisel
No full textUnintentional copper and nickel impurities are common in silicon-based devices due to the abundance of contamination sources in industrial silicon crystallization and wafer processing lines. High solubility and diffusivity result readily in significant impurity concentrations, which cause charge-carrier recombination and reduce the device response. This work confirms that nickel diffuses as fast as copper in silicon, emphasizing the importance of contamination control in silicon-based devices. Copper contamination is known to form recombination-active defects in silicon during illumination, which is observed as copper-related light-induced degradation (Cu-LID). In order to identify the extent of degradation in silicon-based devices, this work focuses on determining the properties of Cu-LID in gallium-doped Czochralski (Cz) silicon, boron-doped Cz-Si, and boron-doped multicrystalline silicon. Cu-LID is determined to be predominantly a bulk recombination effect, and the formed defects are found to be stable at 200°C. Slower Cu-LID is observed in Ga-Si compared to B-Si, suggesting that Cu-LID formation is limited by the effective copper diffusivity. Cu-LID is shown to completely disappear after negative sample surface charging and illumination. The negative surface charge is achieved by corona charging or aluminum oxide deposition. Cu-LID removal is observed to have no impact on classical boron-oxygen-related light-induced degradation (BO-LID), which has previously been shown to recover at 200°C. Unlike BO-LID, the activation energy of Cu-LID is found to depend on the silicon doping concentration. Hence, Cu-LID and BO-LID are concluded to be two different degradation effects, which can occur simultaneously in silicon-based devices.Kiselbaserade elektroniska komponenter är ofta oavsiktligt förorenade av koppar och nickel från otaliga kontaminationskällor i industriella komponentframställningsprocesser. Metallernas höga diffusivitet samt löslighet leder fort till markanta orenhetskoncentrationer, vilka förorsakar rekombination av laddningsbärare och nedsatt komponentrespons. Denna avhandling bekräftar att nickel diffuserar lika fort som koppar i kristallint kisel, vilket betonar vikten av metallorenhetskontroll i kiselbaserade komponenter. Kopparorenheter förorsakar fotodegradadering (Cu-LID) i kisel via formationen av rekombinationsaktiva koppardefekter under illuminering. För att fastställa omfattningen av fotodegradadering i kiselbaserade komponenter, fokuserar denna avhandling på att identifiera egenskaper för Cu-LID i gallium-dopat Czochralski (Cz) kisel, boron-dopat Cz-Si och boron-dopat mångkristallint kisel. Cu-LID finnes orsaka främst bulkrekombination och de formade koppardefekterna är stabila i 200°C. Cu-LID sker långsammare i Ga-Si jämfört med B-Si, vilket antyder att fotodegraderingsprocessen begränsas av den effektiva koppardiffusiviteten. I avhandlingen förhindras kopparrelaterad fotodegradadering fullständigt genom att kombinera negativ kiselytladdning med illuminering. Den negativa ytladdningen skapas via deposition av koronaladdning eller aluminiumoxidtunnfilm. Avlägsning av Cu-LID inverkar inte på klassisk bor-syre-relaterad fotodegraderingen (BO-LID), som förekommer i kisel utan kopparföroreningar och försvinner i 200°C. I motsats till BO-LID beror aktiveringsenergin för Cu-LID på dopingkoncentrationen i kiselmaterialet. Följaktligen fastställs Cu-LID och BO-LID vara två skilda former av fotodegradering, vilka kan förkomma samtidigt i kiselbaserade elektroniska komponenter
Laser performance of Er-doped potassium double tungstate epitaxial layers
No full textLaser operation of Er-doped epitaxial layer of monoclinic double tungstate composition grown onto undoped KYW substrate is demonstrated for the first time. Maximum output power of 16 mW with slope efficiency of 64% is achieved at 1606 nm under direct in-band pumping by a diode-pump Er,Yb-laser at 1522 nm.</p
Investigating the p--π± and p--p--π± dynamics with femtoscopy in pp collisions at s=13 TeV
No full textThe interaction between pions and nucleons plays a crucial role in hadron physics. It represents a fundamental building block of the low-energy QCD dynamics and is subject to several resonance excitations. This work studies the p--π± dynamics using femtoscopic correlations in high-multiplicity pp collisions at s=13 TeV measured by ALICE at the LHC. As the final-state interaction between protons and pions is well constrained by scattering experiments and the study of pionic hydrogen, the results give access to information on the particle-emitting source in pp collisions using the femtoscopy methods. The scaling of the source size of primordial protons and pions against their pair transverse mass is extracted. The results are compared with the source sizes studied with p–p, p--K+, and π±–π± pairs by ALICE in the same collision system and are found to be in agreement for the different particle pairs. This reinforces recent findings by ALICE of a common emission source for all hadron-pairs in pp collisions at LHC energies. Furthermore, the p--p--π± systems are studied using three-particle femtoscopy in pp collisions at s=13 TeV. The presence of three-body effects is analyzed utilizing the cumulant expansion method. In this formalism, the known two-body interactions are subtracted in order to isolate the three-body effects. For both, p--p--π+ and p--p--π-, a non-zero cumulant is found, indicating effects beyond pairwise interactions. These results give information on the coupling of the pion to multiple nucleons
J/ψ production cross section and its dependence on charged-particle multiplicity in p + p collisions at s=200 GeV
No full textWe present a measurement of inclusive J/ψ production at mid-rapidity ( |y|<1 ) in p+p collisions at a center-of-mass energy of s=200 GeV with the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The differential production cross section for J/ψ as a function of transverse momentum ( pT ) for 0<pT<14 GeV/c and the total cross section are reported and compared to calculations from the color evaporation model and the non-relativistic Quantum Chromodynamics model. The dependence of J/ψ relative yields in three pT intervals on charged-particle multiplicity at mid-rapidity is measured for the first time in p+p collisions at s=200 GeV and compared with that measured at s=7 TeV, PYTHIA8 and EPOS3 Monte Carlo generators, and the Percolation model prediction
p-p, p-Lambda, and Lambda-Lambda correlations studied via femtoscopy in pp reactions at root s=7 TeV
No full textWe report on the first femtoscopic measurement of baryon pairs, such as p-p, p-Λ, and Λ-Λ, measured by ALICE at the Large Hadron Collider (LHC) in proton-proton collisions at s=7TeV. This study demonstrates the feasibility of such measurements in pp collisions at ultrarelativistic energies. The femtoscopy method is employed to constrain the hyperon-nucleon and hyperon-hyperon interactions, which are still rather poorly understood. A new method to evaluate the influence of residual correlations induced by the decays of resonances and experimental impurities is hereby presented. The p-p, p-Λ, and Λ-Λ correlation functions were fitted simultaneously with the help of a new tool developed specifically for the femtoscopy analysis in small colliding systems: Correlation Analysis Tool using the Schrödinger equation (CATS). Within the assumption that in pp collisions the three particle pairs originate from a common source, its radius is found to be equal to r0=1.125±0.018(stat)-0.035+0.058(syst) fm. The sensitivity of the measured p-Λ correlation is tested against different scattering parameters, which are defined by the interaction among the two particles, but the statistics is not sufficient yet to discriminate among different models. The measurement of the Λ-Λ correlation function constrains the phase space spanned by the effective range and scattering length of the strong interaction. Discrepancies between the measured scattering parameters and the resulting correlation functions at LHC and RHIC energies are discussed in the context of various models
Measurement of the production of high-p(T) electrons from heavy-flavour hadron decays in Pb-Pb collisions at root s(NN)=2.76 TeV
No full textElectrons from heavy-flavour hadron decays (charm and beauty) were measured with the ALICE detector in Pb-Pb collisions at a centre-of-mass of energy root s(NN) = 2.76 TeV. The transverse momentum (pT) differential production yields at mid-rapidity were used to calculate the nuclear modification factor R-AA in the interval 3 < p(T) < 18 GeV/c. The R-AA shows a strong suppression compared to binary scaling of pp collisions at the same energy (up to a factor of 4) in the 10% most central Pb-Pb collisions. There is a centrality trend of suppression, and a weaker suppression (down to a factor of 2) in semi-peripheral (50-80%) collisions is observed. The suppression of electrons in this broad p(T) interval indicates that both charm and beauty quarks lose energy when they traverse the hot medium formed in Pb-Pb collisions at LHC. (C) 2017 The Author. Published by Elsevier B.V
Di-electron spectroscopy in HADES and CBM : from p + p and n + p collisions at GSI to Au + Au collisions at FAIR
No full textThe study of the electromagnetic structure of hadrons plays an important role in understanding the nature of matter. In particular the emission of lepton pairs out of the hot and dense collision zone in heavy-ion reactions is a promising probe to investigate in-medium properties of hadrons and in general the properties of matter under such extreme conditions. The first experimental observation of an enhanced di-electron yield in the invariant-mass region 0:3 - 0:7 GeV/c2 in p+Be collisions at 4:9 GeV/u beam energy [2] was announced by the DLS collaboration [1]. Recent results of the HADES collaboration show a moderate enhancement above n Dalitz decay contributions for 12C+12C at 1 and 2 GeV/u [3, 4] confirming the DLS results. There are several theoretical explanations of this observation, most of them focusing on possible in-medium modifications of the properties of vector mesons. At low beam energies the question whether the observed excess is related to any in-medium effects remains open because of uncertainties in the description of elementary di-electron sources. In this work the di-electron production in p+p and d+p reactions at a kinetic beam energy of 1:25 GeV/u measured by the HADES spectrometer is discussed. At Ekin = 1:25 GeV/u, i.e. below the n meson production threshold in proton-proton reactions, the delta Dalitz decay is expected to be the most abundant source above the pi 0 Dalitz decay region. The observed large difference in di-electron production in p+p and d+p collisions suggests that di-electron production in the d+p system is dominated by the n+p interaction. In order to separate delta Dalitz decays and np bremsstrahlung the di-electron yield observed in p+p and n+p reactions, both measured at the same beam energy, has been compared. The main interest here is the investigation of iso-spin effects in baryonic resonance excitations and the off-shell production of vector mesons [5]. We indeed observe a large difference in di-electron production in p+p and n+p reactions. Results of these studies will be compared to recent calculations. We will also present our experimentally defined cocktail for heavy-ion data. At much higher beam energies experimental results of the CERES [6] and NA60 [7] collaborations also show an enhancement in the invariant mass region 0:3 - 0:7 GeV/c2, in principle similar to the situation in DLS. A strong excess of lepton pairs observed by recent high energy heavy-ion dilepton experiments hint to a strong influence of baryons, however no data exist at highly compressed baryonic matter, achievable in heavy-ion collisions from 8 - 45 GeV/u beam energy. These conditions would allow to study the expected restoration of chiral symmetry by measuring in-medium modifications of hadronic properties, an experimental program which is foreseen by the future CBM experiment at FAIR. The experimental challenge is to suppress the large physical background on the one hand and to provide a clean identification of electrons on the other hand. In this work, strategies to reduce the combinatorial background in electron pair measurements with the CBM detector are discussed. The main goal is to study the feasibility of effectively reducing combinatorial background with the currently foreseen experimental setup, which does not provide electron identification in front of the magnetic field.Untersuchungen der elektromagnetischen Struktur von Hadronen spielen eine wichtige Rolle um die Eigenschaften von stark wechselwirkender Materie zu verstehen. Insbesondere die Emission von Leptonenpaare aus der heißen und dichten Phase in Schwerionenkollisionen stellt eine vielversprechende Probe in der Untersuchung von veränderten Eigenschaften der Hadronen im Medium und der Eigenschaften von Materie unter extremen Bedingungen dar. Das DLS Experiment [1] beobachtete einen Überschuss der Elektronenpaarausbeute über die Erwartungen im invarianten Massenbereich von 0:3 - 0:7 GeV/c2 in p+Be-Kollisionen bei 4:9 GeV/u Strahlenergie [2]. Neuere Ergebnisse des HADES Experimentes bestätigen diese DLS Resultate und zeigen einen Überschuss von Elektronenpaare über den erwarteten Beiträgen von n Dalitz-Zerfällen für 12C+12C-Reaktionen bei 1 und 2 GeV/u Strahlenergie [3, 4]. Diese Beobachtung wird in verschiedenen theoretischen Ansätzen unterschiedlich erklärt, die meisten Deutungen konzentrieren sich auf Veränderungen der Eigenschaften der Vektormesonen im Medium. Allerdings bleibt diese Interpretation insbesondere bei diesen niedrigen Strahlenergien wegen der großen Unsicherheiten in den elementaren Elektronenpaarquellen unsicher. In dieser Arbeit wurde die mit dem HADES Experiment gemessene Produktion von Elektronenpaare in p+p und in aus d+p extrahierten n+p-Reaktionen bei Strahlenergien von 1:25 GeV/u untersucht. Bei Energien von Ekin = 1:25 GeV/u befindet man sich in Proton-Proton Stößen noch unterhalb der Schwelle für n-Mesonproduktion, daher ist der delta Dalitz-Zerfall die dominante Quelle für Elektronenpaare oberhalb der pi 0 Dalitz-Zerfallsregion. Man beobachtet einen großen Unterschied in den Spektren aus p+p und n+p Reaktionen bei derselben Strahlenergie. Dieser Vergleich ermöglicht es, die Beiträge der delta Dalitz-Zerfälle von denen aus np-Bremsstrahlung zu trennen. Das wesentliche Interesse liegt hier auf der Untersuchung von Isospin-Effekten in der Anregung baryonischer Resonanzen Produktion von Vektormesonen jenseits der Massenschale [5]. Ergebnisse der hier vorgestellten Analyse werden mit neueren Rechnungen verglichen. Ein experimentell bestimmter Cocktail zum Vergleich mit der Elektronenpaar-Produktion in C+C wird vorgestellt. Auch Ergebnnisse der CERES [6] und NA60 [7] Kollaborationen bei höherer Strahlenergie einen Überschuss der Elektronenpaar-Produktion über den Erwartungen im invarianten Massenbereich von 0:3 - 0:7 GeV/c2 zeigen. Erklärungen dieses Überschusses weisen auf einen starken Einfluss von Baryonen auf die Leptonenpaar-Emission hin. Es existieren allerdings noch keine Messungen im Bereich höchster Kompression von baryonischer Materie bzw. höchster Netto-Baryonendichte, die mit Schwerionenkollisionen bei 8 - 45 GeV/u Strahlenergie erreicht werden können. Solche Bedingungen erlauben die Untersuchung der erwarteten Wiederherstellung der spontan gebrochenen Chiralen Symmetrie durch die Messung von Modifikationen der hadronischen Eigenschaften im Medium. Ein solches experimentelles Programm ist einer der Kernpunkte des geplanten CBM-Experimentes an FAIR. Die experimentelle Herausforderung besteht darin, den großen physikalischen Untergrund zu unterdrücken sowie eine saubere Elektronen Identifizierung zu erhalten. In dieser Arbeit wurden detaillierte Machbarkeitsstudien hierzu durchgeführt und es wurde gezeigt, dass mit der entwickelten Strategie der kombinatorische Untergrund mit der vorgeschlagenen Detektoranordnung hinreichend unterdrückt werden kann
Multiplicity dependence of pi, K, and p production in pp collisions at root s=13 TeV
No full textThis paper presents the measurements of π±, K±, p and p¯¯¯ transverse momentum (pT) spectra as a function of charged-particle multiplicity density in proton–proton (pp) collisions at s√ = 13 TeV with the ALICE detector at the LHC. Such study allows us to isolate the center-of-mass energy dependence of light-flavour particle production. The measurements reported here cover a pT range from 0.1 to 20 GeV/c and are done in the rapidity interval |y|<0.5. The pT-differential particle ratios exhibit an evolution with multiplicity, similar to that observed in pp collisions at s√ = 7 TeV, which is qualitatively described by some of the hydrodynamical and pQCD-inspired models discussed in this paper. Furthermore, the pT-integrated hadron-to-pion yield ratios measured in pp collisions at two different center-of-mass energies are consistent when compared at similar multiplicities. This also extends to strange and multi-strange hadrons, suggesting that, at LHC energies, particle hadrochemistry scales with particle multiplicity the same way under different collision energies and colliding systems
Study of the p–p–K + and p–p–K - dynamics using the femtoscopy technique
No full textThe interactions of kaons (K) and antikaons (K ̄) with few nucleons (N) were studied so far using kaonic atom data and measurements of kaon production and interaction yields in nuclei. Some details of the three-body KNN and K ̄ NN dynamics are still not well understood, mainly due to the overlap with multi-nucleon interactions in nuclei. An alternative method to probe the dynamics of three-body systems with kaons is to study the final state interaction within triplet of particles emitted in pp collisions at the Large Hadron Collider, which are free from effects due to the presence of bound nucleons. This Letter reports the first femtoscopic study of p–p–K + and p–p–K - correlations measured in high-multiplicity pp collisions at s = 13 TeV by the ALICE Collaboration. The analysis shows that the measured p–p–K + and p–p–K - correlation functions can be interpreted in terms of pairwise interactions in the triplets, indicating that the dynamics of such systems is dominated by the two-body interactions without significant contributions from three-body effects or bound states
Measurement of (1520) production in pp collisions at = 7 TeV and p-Pb collisions at = 5.02 TeV
No full textThe production of the (1520) baryonic resonance has been measured at midrapidity in inelastic pp collisions at = 7 TeV and in p-Pb collisions at = 5.02 TeV for non-single diffractive events and in multiplicity classes. The resonance is reconstructed through its hadronic decay channel (1520) pK and the charge conjugate with the ALICE detector. The integrated yields and mean transverse momenta are calculated from the measured transverse momentum distributions in pp and p-Pb collisions. The mean transverse momenta follow mass ordering as previously observed for other hyperons in the same collision systems. A Blast-Wave function constrained by other light hadrons (, K, K, p, ) describes the shape of the (1520) transverse momentum distribution up to 3.5 GeV/ in p-Pb collisions. In the framework of this model, this observation suggests that the (1520) resonance participates in the same collective radial flow as other light hadrons. The ratio of the yield of to the yield of the ground state particle remains constant as a function of charged-particle multiplicity, suggesting that there is no net effect of the hadronic phase in p-Pb collisions on the (1520) yield.The production of the (1520) baryonic resonance has been measured at midrapidity in inelastic pp collisions at and in p–Pb collisions at for non-single diffractive events and in multiplicity classes. The resonance is reconstructed through its hadronic decay channel (1520) and the charge conjugate with the ALICE detector. The integrated yields and mean transverse momenta are calculated from the measured transverse momentum distributions in pp and p–Pb collisions. The mean transverse momenta follow mass ordering as previously observed for other hyperons in the same collision systems. A Blast-Wave function constrained by other light hadrons (, K, , p, ) describes the shape of the (1520) transverse momentum distribution up to in p–Pb collisions. In the framework of this model, this observation suggests that the (1520) resonance participates in the same collective radial flow as other light hadrons. The ratio of the yield of to the yield of the ground state particle remains constant as a function of charged-particle multiplicity, suggesting that there is no net effect of the hadronic phase in p–Pb collisions on the (1520) yield.The production of the (1520) baryonic resonance has been measured at midrapidity in inelastic pp collisions at = 7 TeV and in p-Pb collisions at = 5.02 TeV for non-single diffractive events and in multiplicity classes. The resonance is reconstructed through its hadronic decay channel (1520) pK and the charge conjugate with the ALICE detector. The integrated yields and mean transverse momenta are calculated from the measured transverse momentum distributions in pp and p-Pb collisions. The mean transverse momenta follow mass ordering as previously observed for other hyperons in the same collision systems. A Blast-Wave function constrained by other light hadrons (, K, K, p, ) describes the shape of the (1520) transverse momentum distribution up to 3.5 GeV/ in p-Pb collisions. In the framework of this model, this observation suggests that the resonance participates in the same collective radial flow as other light hadrons. The ratio of the yield of to the yield of the ground state particle remains constant as a function of charged-particle multiplicity, suggesting that there is no net effect of the hadronic phase in p-Pb collisions on the (1520) yield
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