We describe the method of measuring the integrated luminosity of the e+e- collider DAΦNE, the Frascati φ-factory. The measurement is done with the KLOE detector selecting large angle Bhabha ...scattering events and normalizing them to the effective cross section. The e+e-→e+e-(γ) cross section is calculated using different event generators which account for the \(\mathcal{O}(\alpha)\) radiative initial and final state corrections, and the φ resonance contribution. The accuracy of the measurement is 0.6%, where 0.3% comes from systematic errors related to the event counting and 0.5% from theoretical evaluations of the cross section.
Using a sample of over 400 million φ→KSKL decays produced during the years 2001 and 2002 at the DAΦNE e+e- collider, the ratio RSπ=Γ(KS→π+π-(γ))/Γ(KS→π0π0) has been measured with the KLOE detector. ...The result is RSπ=2.2555±0.0012stat±0.0021corr-stat±0.0050syst, which is in good agreement with the previously published result based on the KLOE data sample from the year 2000. The average of the KLOE results is RSπ=2.2549±0.0054, reducing the total error by a factor of three, to 0.25%.
The KLOE TDC is a multichannel common start/stop time-to-digital converter, with 32 channels per chip. The time measurement is done digitally by counting 1GHz clock periods generated by an internal ...Delay Locked Loop (DLL). The circuit has a 500ps resolution over a programmable time window of up to 65μs, and is capable of recording up to 16 rising or falling edges per channel. It has a double-edge resolution of 5ns and is capable of resolving a pulse of 3ns width. The experiment requires that the data read out does not introduce dead time on top of the 2μs digitization time of the calorimeter electronics. A multievent architecture has been implemented to satisfy this requirement. The experimental DAQ chain can read framed and zero suppressed data from the internal buffers at a maximum data throughput of 720Mbit/s while the ASIC is recording new events. The chip has been realized as a full-custom device in 0.5μm CMOS technology, it has been fully tested both in the laboratory and on a test beam, all the specifications are met.
A total of 15 000 channels are being produced for the KLOE experiment.
The tracking detector of the KLOE experiment is a large volume drift chamber designed to identify with high efficiency K/sub L/-K/sub S/ decays produced on the /spl Phi/ resonance at the DA/spl ...Phi/NE factory, for a precise measurement of the CP-symmetry violation parameters. The chamber's readout system is designed to run at a peak luminosity of 10/sup 33/ cm/sup -2/ s/sup -1/, bunch crossing period of 2.7 ns, at an expected trigger rate of 10 KHz, with low deadtime (/spl sim/2%). Each of the 12582 readout channels consists of an on-detector preamplifier and a shaper-discriminator circuit which feeds a custom built integrated TDC. Zero-suppressed data collected by the front-end electronics are sent, through a two-level data concentrator, to an online farm and finally are written to tape. The concentrator system is based on custom design and VME busses, on an FDDI switch and commercial processors. A description of the readout system is presented, together with results from KLOE cosmic rays and commissioning at DA/spl Phi/NE runs.
The ATLAS barrel level-1 muon trigger processes hit information from the resistive plate chamber detector, identifying candidate muon tracks and assigning them to a programmable p/sub T/ range and to ...a unique bunch crossing number. The trigger system uses up to seven detector layers and seeks hit patterns compatible with muon tracks in the bending and nonbending projection. The basic principle of the algorithm is to demand a coincidence of hits in the different chamber layers within a path. The width of the road is related to the p/sub T/ threshold to be applied. The system is split into an on-detector and an off-detector part. The on-detector electronics reduces the information from about 350 k channels to about 400 32-bit data words sent via optical fiber to the so-called sector logic (SL). The off-detector SL electronics collects muon candidates and associates them to detector regions-of-interest of /spl Delta//spl eta//spl times//spl Delta//spl Phi/ of 0.1/spl times/0.1. The core of the on-detector electronics is the coincidence matrix ASIC (CMA), which fulfils both the trigger algorithm and the readout of the RPC detector. Each CMA is able to process and readout 192 RPC strips from as many as four detector layers. In order to keep the full level-1 system latency below 2 /spl mu/s, the CMA has to find candidate muon tracks with a latency of a few 25 ns bunch crossing periods. The readout part of the CMA is able to time tag incoming RPC hits with a time interpolator running at the trigger pipeline frequency of 320 MHz and to send the data to the readout system via a serial link. The design of the trigger system and the performances of the ASIC, based on a CMOS 0.18 /spl mu/m technology, are presented.
We have searched with the KLOE detector for the P and CP violating decay η→π+π− in a sample of 1.55×107η's from the decay ϕ→ηγ of ϕ-mesons produced in e+e− annihilations at DAΦNE. No signal is found. ...We obtain the upper limit BR(η→π+π−)<1.3×10−5 at 90% confidence level.
In order to ensure that the resistive plate chambers used in the ATLAS experiment will not show, during their operation, any abnormal aging effect which could degrade their performances, an aging ...test is being performed at X5-GIF, CERN's gamma irradiation facility. In this paper, the latest results are presented, together with an example of successful damage recovery technique.
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