The ATLAS tau trigger

The ATLAS tau trigger consists of three level trigger systems: the first one (L1) is hardware based and uses FPGAs, while the second (L2) and third levels (EF -Event Filter-) are software based and use commodity computers (2 x Intel Harpertown quad-core 2.5 GHz), running scientific linux 5. In this contribution, we discuss both the physics characteristics of tau leptons and the technical solutions to quick data access and fast algorithms. We show that L1 selects narrow jets in the calorimeter with an overall rejection against QCD jets of 300, whilst L2 and EF (referred together as High Level Trigger -HLT-) use all the detectors with full granularity and apply a typical rejection of 15 within the stringent timing requirements of the LHC. In the HLT there are two complementary approaches: specialized, fast algorithms are used at L2, while more refined and sophisticated algorithms, imported from the offline, are utilized in the EF

New Method for Reconstructing Effective Top Quark Spin

We propose a new method for reconstructing an effective spin direction of a semi-leptonically decayed top quark. The method is simple: for instance, it does not require the spin information of the antitop quark in a ttbar event. The reconstructed effective spin is expected to be useful in hadron collider experiments. We demonstrate its usefulness in an analysis of the top decay vertex.Comment: 10 pages, 6 figures; one reference added; version to appear in Phys.Lett.

Search for Anomalous Couplings in Top Decay at Hadron Colliders

We present a quantitative study on sensitivities to the top-decay anomalous couplings, taking into account realistic experimental conditions expected at Tevatron and LHC. A double angular distribution of W and charged lepton in the top decay is analyzed, using ttbar events in the lepton+jets channel. In order to improve sensitivities to the anomalous couplings, we apply two techniques: (1) We use a likelihood fitting method for full kinematical reconstruction of each top event. (2) We develop a new effective spin reconstruction method for leptonically-decayed top quarks; this method does not require spin information of the antitop side. For simplicity, we neglect couplings of right-handed bottom quark as well as CP violating couplings. The 95% C.L. estimated bound on a ratio of anomalous couplings reads -0.81 < f_2/f_1 < -0.70, -0.12<f_2/f_1<0.14 using 1000 reconstructed top events at Tevatron, while -0.74<f_2/f_1<-0.72, -0.01<f_2/f_1<0.01 is expected with 100k reconstructed top events at LHC, where only statistical errors are taken into account. A two-fold ambiguity in the allowed range remains when the number of events exceeds a few hundred.Comment: 21 pages, 15 figure

GR@PPA 2.7 event generator for pppp/ppˉp\bar{p} collisions

The GR@PPA event generator has been updated to version 2.7. This distribution provides event generators for $V$ ($W$ or $Z$) + jets ($\leq$ 4 jets), $VV$ + jets ($\leq$ 2 jets) and QCD multi-jet ($\leq$ 4 jets) production processes at $pp$ and $p\bar{p}$ collisions, in addition to the four bottom quark productions implemented in our previous work (GR@PPA\_4b). Also included are the top-pair and top-pair + jet production processes, where the correlation between the decay products are fully reproduced at the tree level. Namely, processes up to seven-body productions can be simulated, based on ordinary Feynman diagram calculations at the tree level. In this version, the GR@PPA framework and the process dependent matrix-element routines are separately provided. This makes it easier to add further new processes, and allows users to make a choice of processes to implement. This version also has several new features to handle complicated multi-body production processes. A systematic way to combine many subprocesses to a single base-subprocess has been introduced, and a new method has been adopted to calculate the color factors of complicated QCD processes. They speed up the calculation significantly.Comment: 21 pages, no figur

The ATLAS tau trigger

The ATLAS tau trigger has three levels: the first one (L1) is hardware based and uses FPGAs, while the second (L2) and third levels (EF -Event Filter-) are software based and use commodity computers (2 x Intel Harpertown quad-core 2.5 GHz), running scientific linux 4. In this contribution we discuss both the physics characteristics of tau leptons and the technical solutions to quick data access and fast algorithms. We show that L1 selects narrow jets in the calorimeter with an overall rejection against QCD jets of 300, whilst L2 and EF (referred together as High Level Trigger -HLT-) use all the detectors with full granularity and apply a typical rejection of 15 within the stringent timing requirements of the LHC. In the HLT there are two complementary approaches: specialized, fast algorithms are used at L2, while more refined and sophisticated algorithms, imported from the offline, are utilized in the EF

Integration of GRACE and PYTHIA

We have successfully developed a technique to integrate an automatic event-generator generation system GRACE and a general-purpose event generator framework PYTHIA. The codes generated by GRACE are embedded in PYTHIA in the created event generator program. The embedded codes give information on parton-level hard interactions directly to PYTHIA. The choice of PDF is controlled by the ordinary parameter setting in PYTHIA. This technique enables us to create easy-to-handle event generators for any processes in hadron collisions. Especially, in virtue of large capability of GRACE, we can easily deal with those processes containing many (four or more) partons in the final state, such as multiple heavy particle productions. This project is being carried out as a collaboration between the Japanese Atlas group and the Minami-Tateya group, aiming at developing event generators for Tevatron and LHC experiments

Volume reduction of municipal solid wastes contaminated with radioactive cesium by ferrocyanide coprecipitation technique

Municipal solid wastes (MSW) with elevated concentrations of radioactive cesium (rad-Cs hereafter) have been generated in some areas of Japan in the aftermath of the Fukushima Daiichi Nuclear Power Plant (F1 hereafter) accident. Both recycling and final disposal of the contaminated MSW have become a difficult problem in the affected areas, resulting in accumulation of treated residues in the treatment facilities. The rad-Cs in MSW, especially fly ash, often showed a high leaching rate. Extraction of contaminated MSW with water or hot oxalic acid followed by selective removal of rad-Cs from the extract using ferrocyanide (Fer hereafter) coprecipitation technique could be an ultimate solution for waste volume reduction. The MSW extracts contain various metal components as well as chelating reagents like oxalic acid, and are often very saline. The composition of the extract varies widely depending on waste sources, applied treatment techniques, and rad-Cs extraction method etc. The applicability of the Fer coprecipitation technique had to be tested and validated before it could be applied for actual treatment. In this work, we applied the Fer technique and observed removal of cesium (Cs) from water and oxalic acid extracts (all spiked with rad-Cs tracer or stable Cs) of various MSW samples collected from uncontaminated areas. Finally, the Fer technique was applied on site for removal of rad-Cs in the extracts of contaminated MSW. By modifying coprecipitation conditions according to solution matrix, Cs removal rates of higher than 95 % could be obtained

Kinetic model of thermophilic L-lactate fermentation by Bacillus coagulans combined with real-time PCR quantification.

A simple L-lactate fermentation of organic wastes at pH 5.5 and 55 degrees C under nonsterile conditions using Bacillus coagulans can be suitable for L-lactate fermentation of garbage. A mathematical model that simulated the lactate fermentation characteristics of B. coagulans was developed by focusing on the inhibitory effects of substrate, lactate (product) and NaCl, and bacterial growth. Basic fermentation experiments were performed using simple substrates to derive fundamental parameters of growth rate and inhibition effects. The model was then applied to fermentations using simple substrates and artificial kitchen garbage in order to verify its applicability. Microbial concentration, a key state variable of the model was measured using both real-time polymerase chain reaction (PCR) and traditional methods. The results of these methods were compared for experimental cases in which only soluble substrates were used. B. coagulans concentrations were suitably measured using real-time PCR, even when traditional measurement methods for microbial concentrations cannot be used. The results indicate that the developed model and biomass measurement can be used to evaluate lactate fermentations using both simple and complex substrates. These proposed methods would be useful for developing a new bacterial function-based mathematical model for more complex acid fermentations