The calorimetry at the future e+ e- linear collider

The physics programme for a coming electron linear collider is dominated by events with final states containing many jets. We develop in this paper the opinion that the best approach is to optimise the independent measurement of the tracks in the tracker, the photons in the electromagnetic calorimeter and the neutral hadrons in the camorimetry, together with a good lepton identification. This can be achieved with a high granularity calorimetry providing particle separation, through an efficient energy flow algorithm.Comment: 7 pages, 6 Postscript figures, to appear in the Proceedings of the APS / DPF / DPB Summer Study on the Future of Particle Physics (Snowmass 2001), Snowmass, Colorado, 30 Jun - 21 Jul 200

GARLIC: GAmma Reconstruction at a LInear Collider experiment

The precise measurement of hadronic jet energy is crucial to maximise the physics reach of a future Linear Collider. An important ingredient required to achieve this is the efficient identification of photons within hadronic showers. One configuration of the ILD detector concept employs a highly granular silicon-tungsten sampling calorimeter to identify and measure photons, and the GARLIC algorithm described in this paper has been developed to identify photons in such a calorimeter. We describe the algorithm and characterise its performance using events fully simulated in a model of the ILD detector

Improving the Jet Reconstruction with the Particle Flow Method; an Introduction

To be published in the CALOR04 conference proceedings, Perugia April 2004At the future electron-positron TeV linear collider, the reachable physics will be strongly dependent on the detector capability to reconstruct high energy jets in multi-jet environment. At LEP, SLD experiments, a technique combining charged tracks and calorimetric information has been used to improve the jet energy/direction reconstruction. Starting from this experience, it has been proposed to go from partial individual particle reconstruction to complete (or full) individual reconstruction. Different studies have shown that the reachable resolution is far beyond any realistic hope from calorimetric-only measurement

Fractal Dimension of Particle Showers Measured in a Highly Granular Calorimeter

We explore the fractal nature of particle showers using Monte-Carlo simulation. We define the fractal dimension of showers measured in a high granularity calorimeter designed for a future lepton collider. The shower fractal dimension reveals detailed information of the spatial configuration of the shower. %the information hidden in the details of shower spatial configuration, It is found to be characteristic of the type of interaction and highly sensitive to the nature of the incident particle. Using the shower fractal dimension, we demonstrate a particle identification algorithm that can efficiently separate electromagnetic showers, hadronic showers and non-showering tracks. We also find a logarithmic dependence of the shower fractal dimension on the particle energy.Comment: 4 pages, 5 figure

Constraints on Climate Sensitivity from Space-Based Measurements of Low-Cloud Reflection

Physical uncertainties in global-warming projections are dominated by uncertainties about how the fraction of incoming shortwave radiation that clouds reflect will change as greenhouse gas concentrations rise. Differences in the shortwave reflection by low clouds over tropical oceans alone account for more than half of the variance of the equilibrium climate sensitivity (ECS) among climate models, which ranges from 2.1 to 4.7 K. Space-based measurements now provide an opportunity to assess how well models reproduce temporal variations of this shortwave reflection on seasonal to interannual time scales. Here such space-based measurements are used to show that shortwave reflection by low clouds over tropical oceans decreases robustly when the underlying surface warms, for example, by −(0.96 ± 0.22)% K^(−1) (90% confidence level) for deseasonalized variations. Additionally, the temporal covariance of low-cloud reflection with temperature in historical simulations with current climate models correlates strongly (r = −0.67) with the models’ ECS. Therefore, measurements of temporal low-cloud variations can be used to constrain ECS estimates based on climate models. An information-theoretic weighting of climate models by how well they reproduce the measured deseasonalized covariance of shortwave cloud reflection with temperature yields a most likely ECS estimate around 4.0 K; an ECS below 2.3 K becomes very unlikely (90% confidence)

Factors influencing the Quality of the Coach-Athlete Relationship During the Specialisation Phase in Female Football

The Coach-Athlete Relationship (CAR) is a dynamic and dyadic relationship formed between athlete and coach that is supportive of enhanced levels of coaching effectiveness, athlete wellbeing and sport performance. However, a paucity of research exists that has explored coach and athlete perceptions of effective CARs across developmental stages in female sport. Following ethical approval, female footballers (n = 18) and high-performance football coaches (n = 6) in specialisation phase age groups (U12, U14, U16), on the FA female talent pathway, completed the coach or athlete version of the coach-athlete relationship questionnaire (CART-Q), and qualitative open-ended questions exploring coach-athlete perceptions of effective CARs. CART-Q scores were directly compared across specialisation phase age groups; responses to open-ended questions were thematically analysed using a constant comparison method and presented as direct textual quotations. The findings indicated: positive trends (complimentarity; co-orientation), stable trend (commitment), and unstable trend (closeness) for CART-Q scores across age groups. Significantly, closeness scores (U16) were lower in comparison with all other age groups. Furthermore, qualitative responses identified that perceptions of CAR supportive conditions varied across age-groups: establishing ‘trust’ and an ‘open dialogue’ emerged as common themes for all age groups; ‘feeling listened to’ emerged as a common theme in the U16 age group only. Findings suggest that gender and athlete developmental-stage represent influential criteria determining perceived CAR effectiveness in sport. It is recommended that future research is grounded in the context of female sport, and that applied practitioners fully consider the influence of developmental and psychological differences

Measuring the Higgs Branching Fraction into two Photons at Future Linear \ee Colliders

We examine the prospects for measuring the \gaga branching fraction of a Standard Model-like Higgs boson with a mass of 120 GeV at the future TESLA linear \ee collider, assuming an integrated luminosity of 1 ab$^{-1}$ and center-of-mass energies of 350 GeV and 500 GeV. The Higgs boson is produced in association with a fermion pair via the Higgsstrahlung process \ee $\to ZH$, with $Z \to$ \qq or \nn, or the WW fusion reaction $e^+e^- \to \nu_e \bar{\nu_e} H$. A relative uncertainty on BF(\hgg) of~16% can be achieved in unpolarized \ee collisions at $\sqrt{s}$=~500 GeV, while for $\sqrt{s}$=~350 GeV the expected precision is slightly poorer. With appropriate initial state polarizations $\Delta$BF(\hgg)/BF(\hgg) can be improved to 10%. If this measurement is combined with the expected error for the total Higgs width, a precision of 10% on the \gaga Higgs boson partial width appears feasible.Comment: 14 pages, 5 figure

Knowledge-based design of reagentless fluorescent biosensors from a designed ankyrin repeat protein

Designed ankyrin repeat proteins (DARPins) can be selected from combinatorial libraries to bind any target antigen. They show high levels of recombinant expression, solubility and stability, and contain no cysteine residue. The possibility of obtaining, from any DARPin and at high yields, fluorescent conjugates which respond to the binding of the antigen by a variation of fluorescence, would have numerous applications in micro- and nano-analytical sciences. This possibility was explored with Off7, a DARPin directed against the maltose binding protein (MalE) from Escherichia coli, with known crystal structure of the complex. Eight residues of Off7, whose solvent accessible surface area varies on association with the antigen but which are not in direct contact with the antigen, were individually mutated into cysteine and then chemically coupled with a fluorophore. The conjugates were ranked according to their relative sensitivities. All of them showed an increase in their fluorescence intensity on antigen binding by >1.7-fold. The best conjugate retained the same affinity as the parental DARPin. Its signal increased linearly and specifically with the concentration of antigen, up to 15-fold in buffer and 3-fold in serum when fully saturated, the difference being mainly due to the absorption of light by serum. Its lower limit of detection was equal to 0.3 nM with a standard spectrofluorometer. Titrations with potassium iodide indicated that the fluorescence variation was due to a shielding of the fluorescent group from the solvent by the antigen. These results suggest rules for the design of reagentless fluorescent biosensors from any DARPi