scholarly journals Challenges for FCC-ee luminosity monitor design

2022 ◽  
Vol 137 (1) ◽  
Author(s):  
Mogens Dam
Keyword(s):  
Interaction Point ◽  
Final State ◽  
Detector Acceptance ◽  
Bhabha Scattering ◽  
Electrons And Positrons ◽  
Order Of Magnitude ◽  
Acceptance Limits ◽  
The One ◽  
Main Detector ◽  
Absolute Luminosity

AbstractFor cross section measurements, an accurate knowledge of the integrated luminosity is required. The FCC-ee physics programme at and around the Z pole sets the ambitious precision goal of $$10^{-4}$$ 10 - 4 on the absolute luminosity measurement and one order of magnitude better on the relative measurement between energy scan points. The luminosity is determined from the rate of Bhabha scattering, $$\mathrm {e^+e^- \rightarrow e^+e^-}$$ e + e - → e + e - , where the final state electrons and positrons are detected in dedicated monitors covering small angles from the outgoing beam directions. The constraints on the luminosity monitors are multiple: (i) they are placed inside the main detector volume only about 1 m from the interaction point; (ii) they are centred around the outgoing beam directions and do not satisfy the normal axial detector symmetry; (iii) their coverage is limited by the beam pipe, on the one hand, and by the requirement to stay clear of the main detector acceptance, on the other; (iv) the steep angular dependence of the Bhabha scattering process imposes a precision on the acceptance limits at about 1 $$\upmu $$ μ rad, corresponding to an absolute geometrical precision of $${\mathcal {O}}(1\,\upmu \text {m})$$ O ( 1 μ m ) on the monitor radial dimensions; and v) the very high bunch-crossing rate of 50 MHz during the Z-pole operation calls for fast readout electronics. Inspired by second-generation LEP luminosity monitors, which achieved an experimental precision of $$3.4 \times 10^{-4}$$ 3.4 × 10 - 4 on the absolute luminosity measurement (Abbiendi et al. in Eur Phys J C 14:373–425, 2000), a proposed ultra-compact solution is based on a sandwich of tungsten-silicon layers. A vigorous R&D programme is needed in order to ensure that such a solution satisfies the more challenging FCC-ee requirements.

scholarly journals Δ-Isobar contribution to the pion production in the reaction pp → {pp}sπ0

2019 ◽  
Vol 204 ◽  
pp. 01015
Author(s):  
Yuriy Uzikov
Keyword(s):  
Excitation Energy ◽  
Cross Section ◽  
Pion Production ◽  
Forward Direction ◽  
Dominant Contribution ◽  
Final State ◽  
Proton Pair ◽  
Order Of Magnitude ◽  
The Cross ◽  
The One

ANKE@COSY data on the cross section of the reaction pp → {pp}sπ0, where {pp}s is the proton pair in the 1S 0 state at small excitation energy Epp = 0 – 3 MeV, obtained at beam energies 0.5 - 2.0 GeV are analyzed within the one-pion exchange model. The model involves the subprocess π0 p → π0 p and accounts for the final state pp-interaction. A broad maximum observed in the cross section of the reaction pp → {pp}sπ0 at 0.5 - 1.4 GeV in the forward direction is explained by this model as a dominant contribution of the isospin $\cfrac{3}{2}$ in the π0 p-scattering. The second bump in data at 2 GeV is underpredicted within this model by one order of magnitude. An explicit excitation of the Δ(1232)-isobar using the box-diagram is also considered in the region of the first maximum.

Theoretical studies on the one- and two-photon absorption of tetrabenzoporphyrins and phthalocyanines

2004 ◽  
Vol 82 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Xin Zhou ◽  
Ai-Min Ren ◽  
Ji-Kang Feng ◽  
Xiao-Juan Liu
Keyword(s):  
Dipole Moment ◽  
Cross Sections ◽  
Density Functional ◽  
Transition Dipole Moment ◽  
Photon Absorption ◽  
Transition Dipole ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Order Of Magnitude ◽  
The One

The one-photon absorption (OPA) properties of tetrabenzoporphyrins (TBPs) and phthalocyanines (Pcs) were studied using the semiempirical ZINDO method and time-dependent density functional theory (TDDFT), respectively. The compared results confirmed that the semiempirical ZINDO method was reasonably reliable when calculating the OPA of tetrabenzoporphyrins and phthalocyanines. On the basis of the OPA properties obtained from the ZINDO method, two-photon absorption (TPA) properties of two series of molecules were investigated, using ZINDO and sum-over-states (SOS) methods. The results showed that the TPA cross-sections of all molecules were in the range of 220.6 × 10–50 – 345.9 × 10–50 cm4·s·photon–1, which were in the same order of magnitude as the values reported in the literature. The relatively larger δ(ω) value for Pcs with respect to that for corresponding TBPs originates from larger intramolecular charge transfer, which can be characterized by the difference of dipole moment between S0 and S1 and the transition dipole moment between S1 and S5.Key words: two-photon absorption, ZINDO, sum-over-states, tetrabenzoporphyrin, phthalocyanines.

scholarly journals On the connection between quark propagation and hadronization

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Alberto Accardi ◽  
Andrea Signori
Keyword(s):  
Sum Rules ◽  
Mass Term ◽  
Final State ◽  
Mass Generation ◽  
Gauge Invariant ◽  
Dynamical Generation ◽  
Dynamical Quark Mass ◽  
Complete Set ◽  
Fragmentation Functions ◽  
The One

AbstractWe investigate the properties and structure of the recently discussed “fully inclusive jet correlator”, namely, the gauge-invariant field correlator characterizing the final state hadrons produced by a free quark as this propagates in the vacuum. Working at the operator level, we connect this object to the single-hadron fragmentation correlator of a quark, and exploit a novel gauge invariant spectral decomposition technique to derive a complete set of momentum sum rules for quark fragmentation functions up to twist-3 level; known results are recovered, and new sum rules proposed. We then show how one can explicitly connect quark hadronization and dynamical quark mass generation by studying the inclusive jet’s gauge-invariant mass term. This mass is, on the one hand, theoretically related to the integrated chiral-odd spectral function of the quark, and, on the other hand, is experimentally accessible through the E and $${\widetilde{E}}$$ E ~ twist-3 fragmentation function sum rules. Thus, measurements of these fragmentation functions in deep inelastic processes provide one with an experimental gateway into the dynamical generation of mass in Quantum Chromodynamics.

Properties of Relativistic Mean-Field Theory

2007 ◽  
Author(s):  
Kenneth G. Dyall ◽  
Knut Faegri
Keyword(s):  
Mean Field Theory ◽  
Mean Field ◽  
Field Method ◽  
Basis Sets ◽  
Electron Interaction ◽  
Relativistic Mean Field ◽  
Dirac Equations ◽  
Electrons And Positrons ◽  
The One ◽  
Atomic Structure Calculations

We have previously seen how the Dirac equation for one particle requires some rather special consideration and interpretation in order to arrive at a form that is able to treat electrons and positrons on an equal footing. These problems persist also when we go to systems with more than one electron. One might think that the extension to several electrons should not introduce dramatic changes. After all, we noted that even the one-electron problem must be viewed as a many-electron (and -positron) system in order to arrive at a consistent description. The problem with introducing more electrons is that electron–electron interactions that were previously small—for the one-electron case typically arising from vacuum polarization and self-interaction—now occur to the same order as the kinetic energy and the interaction with the potential. So while a perturbative approach such as QED can use the solutions of the one-electron Dirac equations as a very good starting approximation to a more accurate description of the full system, the same would not work for a system with more electrons because it would mean neglecting interactions of the same magnitude as the zeroth-order energy. For applications to quantum chemistry, the treatment of the entire electron–electron interaction as a perturbation would be hopelessly impractical, as it is even in manyelectron relativistic atomic structure calculations. The technique for dealing with this problem is well known from nonrelativistic calculations on many-electron systems. One-particle basis sets are developed by considering the behavior of the single electron in the mean field of all the other electrons, and while this neglects a smaller part of the interaction energy, the electron correlation, it provides a suitable starting point for further variational or perturbational treatments to recover more of the electron–electron interaction. It is only natural to pursue the same approach for the relativistic case. Thus one may proceed to construct a mean-field method that can be used as a basis for the perturbation theory of QED.

scholarly journals Role of Groundwater-Borne Geogenic Phosphorus for the Internal P Release in Shallow Lakes

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1783 ◽  
Author(s):  
Catharina S. Nisbeth ◽  
Søren Jessen ◽  
Ole Bennike ◽  
Jacob Kidmose ◽  
Kasper Reitzel
Keyword(s):  
Lake Sediment ◽  
Trophic State ◽  
Driving Factor ◽  
Original Source ◽  
Depth Profiles ◽  
P Release ◽  
Order Of Magnitude ◽  
The One ◽  
Total P

This study explores the under-investigated issue of groundwater-borne geogenic phosphorus (P) as the potential driving factor behind accumulation of P in lake sediment. The annual internally released P load from the sediment of the shallow, hypereutrophic and groundwater-fed lake, Nørresø, Denmark, was quantified based on total P (TP) depth profiles. By comparing this load with previously determined external P loadings entering the lake throughout the year 2016–2017, it was evident that internal P release was the immediate controller of the trophic state of the lake. Nevertheless, by extrapolating back through the Holocene, assuming a groundwater P load corresponding to the one found at present time, the total groundwater P input to the lake was found to be in the same order of magnitude as the total deposit P in the lake sediment. This suggests that groundwater-transported P was the original source of the now internally cycled P. For many lakes, internal P cycling is the immediate controller of their trophic state. Yet, this does not take away the importance of the external and possibly geogenic origin of the P accumulating in lake sediments, and subsequently being released to the water column.

scholarly journals A novel method of ESR oscillating magnetization value determination in strongly correlated metals

2018 ◽  
Vol 185 ◽  
pp. 02003 ◽  
Author(s):  
Marat Gilmanov ◽  
Alexey Semeno ◽  
Alexander Samarin ◽  
Sergey Demishev
Keyword(s):  
Resonance Field ◽  
Simple Expression ◽  
60 Ghz ◽  
Strongly Correlated ◽  
Static Magnetization ◽  
Spin Resonance ◽  
Order Of Magnitude ◽  
Novel Method ◽  
Value Determination ◽  
The One

We propose a powerful method of direct measurement of oscillating magnetization by the electron spin resonance, based on dependence of resonant conditions on geometry of the experiment. Theoretical consideration of the matter leads to a simple expression for oscillating magnetization. Approbation of this method is implemented by means of cavity ESR spectrometer (60 GHz) on two diverse metallic systems, where static magnetization at the resonance field varies by an order of magnitude. Quantitative values of oscillating magnetization (905 G for EuB6 at T = 4.2 K and 94 G for CeB6 at T = 1.8 K) are in appropriate agreement with the one obtained by the other methods.

scholarly journals Collagen Fibril Diameter in Relation to Bone Site and to Calcium/Phosphorus Ratio

2006 ◽  
Vol 6 ◽  
pp. 1109-1113 ◽  
Author(s):  
Panagiotis Berillis ◽  
Dimitris Emfietzoglou ◽  
Margaret Tzaphlidou
Keyword(s):  
Collagen Fibril ◽  
Male Rats ◽  
Structural Parameter ◽  
Mean Values ◽  
Electron Microscopy Analysis ◽  
Calcium Phosphorus ◽  
Order Of Magnitude ◽  
Microscopy Analysis ◽  
The One ◽  
Fibril Diameter

The collagen fibril diameter was measured in cortical bone samples from the femoral neck, rear and front tibia of female and male rats and rabbits using electron microscopy analysis. In most cases, statistically significant differences in mean fibril diameter values between different bone sites were detected. The order of magnitude for the above structural parameter was the same for both genders in both experimental species. In rats, the greatest mean diameter value was that for the femoral, while in rabbits, the one for the rear tibia demonstrating a dependence on bone use and life style. An important aspect was the agreement between these observations and the mean values for Ca/P ratio, as observed in previous experiments, in the same bone sites and animals. Collagen fibril diameter and Ca/P ratio can both serve as indexes of bone quality.

Hardware Inexact Grammar Parser

2017 ◽  
Vol 31 (11) ◽  
pp. 1759025
Author(s):  
Alexandros C. Dimopoulos ◽  
Christos Pavlatos ◽  
George Papakonstantinou
Keyword(s):  
Parallel Algorithm ◽  
Grammar Rules ◽  
Field Programmable ◽  
Order Of Magnitude ◽  
Programmable Gate Arrays ◽  
Extended Operation ◽  
Hardware Description ◽  
The One ◽  
Context Free ◽  
Parse Table

In this paper, a platform is presented, that given a Stochastic Context-Free Grammar (SCFG), automatically outputs the description of a parser in synthesizable Hardware Description Language (HDL) which can be downloaded in an FPGA (Field Programmable Gate Arrays) board. Although the proposed methodology can be used for various inexact models, the probabilistic model is analyzed in detail and the extension to other inexact schemes is described. Context-Free Grammars (CFG) are augmented with attributes which represent the probability values. Initially, a methodology is proposed based on the fact that the probabilities can be evaluated concurrently with the parsing during the parse table construction by extending the fundamental parsing operation proposed by Chiang & Fu. Using this extended operation, an efficient architecture is presented based on Earley’s parallel algorithm, which given an input string, generates the parse table while evaluating concurrently the probabilities of the generated dotted grammar rules in the table. Based on this architecture, a platform has been implemented that automatically generates the hardware design of the parser given a SCFG. The platform is suitable for embedded systems applications where a natural language interface is required or in pattern recognition tasks. The proposed hardware platform has been tested for various SCFGs and was compared with previously presented hardware parser for SCFGs based on Earley’s parallel algorithm. The hardware generated by the proposed platform is much less complicated than the one of comparison and succeeds a speed-up of one order of magnitude.

scholarly journals A plume-in-grid approach to characterize air quality impacts of aircraft emissions at the Hartsfield–Jackson Atlanta International Airport

2013 ◽  
Vol 13 (18) ◽  
pp. 9285-9302 ◽  
Author(s):  
J. Rissman ◽  
S. Arunachalam ◽  
M. Woody ◽  
J. J. West ◽  
T. BenDor ◽  
...  
Keyword(s):  
Air Quality ◽  
Grid Cell ◽  
Ground Level ◽  
Grid Cells ◽  
Aircraft Emissions ◽  
International Airport ◽  
Grid Approach ◽  
Subgrid Scales ◽  
Order Of Magnitude ◽  
The One

Abstract. This study examined the impacts of aircraft emissions during the landing and takeoff cycle on PM2.5 concentrations during the months of June and July 2002 at the Hartsfield–Jackson Atlanta International Airport. Primary and secondary pollutants were modeled using the Advanced Modeling System for Transport, Emissions, Reactions, and Deposition of Atmospheric Matter (AMSTERDAM). AMSTERDAM is a modified version of the Community Multiscale Air Quality (CMAQ) model that incorporates a plume-in-grid process to simulate emissions sources of interest at a finer scale than can be achieved using CMAQ's model grid. Three fundamental issues were investigated: the effects of aircraft on PM2.5 concentrations throughout northern Georgia, the differences resulting from use of AMSTERDAM's plume-in-grid process rather than a traditional CMAQ simulation, and the concentrations observed in aircraft plumes at subgrid scales. Comparison of model results with an air quality monitor located in the vicinity of the airport found that normalized mean bias ranges from −77.5% to 6.2% and normalized mean error ranges from 40.4% to 77.5%, varying by species. Aircraft influence average PM2.5 concentrations by up to 0.232 μg m−3 near the airport and by 0.001–0.007 μg m−3 throughout the Atlanta metro area. The plume-in-grid process increases concentrations of secondary PM pollutants by 0.005–0.020 μg m−3 (compared to the traditional grid-based treatment) but reduces the concentration of non-reactive primary PM pollutants by up to 0.010 μg m−3, with changes concentrated near the airport. Examination of subgrid-scale results indicates that median aircraft contribution to grid cells is higher than median puff concentration in the airport's grid cell and outside of a 20 km × 20 km square area centered on the airport, while in a 12 km × 12 km square ring centered on the airport, puffs have median concentrations over an order of magnitude higher than aircraft contribution to the grid cells. Maximum puff impacts are seen within the 12 km × 12 km ring, not in the airport's own grid cell, while maximum grid cell impacts occur within the airport's grid cell. Twenty-one (21)% of all aircraft-related puffs from the Atlanta airport have at least 0.1 μg m−3 PM2.5 concentrations. Near the airport, median daily puff concentrations vary between 0.017 and 0.134 μg m−3 (0.05 and 0.35 μg m−3 at ground level), while maximum daily puff concentrations vary between 6.1 and 42.1 μg m−3 (7.5 and 42.1 μg m−3 at ground level) during the 2-month period. In contrast, median daily aircraft contribution to grid concentrations varies between 0.015 and 0.091 μg m−3 (0.09 and 0.40 μg m−3 at ground level), while the maximum varies between 0.75 and 2.55 μg m−3 (0.75 and 2.0 μg m−3 at ground level). Future researchers may consider using a plume-in-grid process, such as the one used here, to understand the impacts of aircraft emissions at other airports, for proposed future airports, for airport expansion projects under various future scenarios, and for other national-scale studies specifically when the maximum impacts at fine scales are of interest.

scholarly journals Effect of ionospheric depth on the ionospheric feedback instability: cutoff and subsequent <I>E</I><sub>||</sub> modes

2010 ◽  
Vol 28 (9) ◽  
pp. 1777-1794 ◽  
Author(s):  
R. Cosgrove ◽  
R. Doe
Keyword(s):  
Growth Rate ◽  
Electric Fields ◽  
Finite Thickness ◽  
Higher Order ◽  
Plasma Structure ◽  
Higher Order Modes ◽  
Order Of Magnitude ◽  
E Region ◽  
The One ◽  
Two Fluid

Abstract. The ionospheric feedback instability (IFI), which involves feedback between ionospheric modifications and waves reflected off the magnetosphere, has up to this point been analyzed in terms of field line integrated (FLI) ionospheric quantities, that is, with the assumption that the ionospheric thickness can be ignored. In this work we test this assumption by solving the two-fluid equations for a representative ionospheric slab of finite thickness. We find that the results are for the most part incompatible with a description in terms of FLI quantities, and that their use can easily lead to an order of magnitude overestimation of the growth rate. This occurs because the first eigenmode, which is the one compatible with an FLI description, is cutoff above a certain frequency, leaving only higher order modes with wavelengths along B that are subsumed by the slab. Taking the results at face value, the parallel electric fields associated with the higher order modes are a possible contributor to electron heating and plasma structure in the E-region ionosphere.

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