Topology Dependence of Event Properties in Hadronic Z Decays

Three-jet events are studied for different event topologies. Experimental evidence is presented that the multiplicities of quark and gluon jets depend both on the jet energy and on the angles between the jets

The Beetle Reference Manual - chip version 1.3, 1.4 and 1.5

This paper details the electrical specifications, operating conditions and port definitions of the readout chips Beetle 1.3, 1.4 and 1.5. The chip is developed for the LHCb experiment and fulfils the requirements of the silicon vertex detector (VELO, PUS), the silicon tracker and the RICH detectors in case of multi-anode photomultiplier readout. It integrates 128 channels with low-noise charge-sensitive preamplifiers and shapers. The pulse shape can be chosen such that it complies with LHCb specifications: a peaking time of 25 ns with a remainder of the peak voltage after 25 ns of less than 30%. A comparator per channel with configurable polarity provides a binary signal. Four adjacent comparator channels are being ORed and brought off chip via LVDS ports. Either the shaper or comparator output is sampled with the LHC bunch-crossing frequency of 40 MHz into an analogue pipeline. This ring buffer has a programmable latency of max. 160 sampling intervals and an integrated derandomising buffer of 16 stages. For analogue readout data is multiplexed with up to 40 MHz onto 1 or 4 ports. A binary readout mode operates at up to 80 MHz output rate on two ports. Current drivers bring the serialised data off chip. The chip can accept trigger rates up to 1.1 MHz to perform a dead-timeless readout within 900 ns per trigger. For t estab ility and calibration purposes, a charge injector with adjustable pulse height is implemented. The bias settings and various other parameters can b

An improved theoretical prediction for the 2-jet rate in e+e- annihilation

We show that an Ansatz to resum all leading and next-to-leading logarithms in the theoretical prediction for the 2-jet rate in e+e- -> hadrons, where jets are defined with the k_t-algorithm, is consistent with a full O(alpha_s^2) calculation done by Monte Carlo integration. From the asymptotic behaviour of the full O(alpha_s^2) calculation we extract the subleading coefficient G_21 and the constant C_2

The Beetle Reference Manual: chip version 1.2

This paper details the electrical specifications, operating conditions and port definitions of the readout chip Beetle 1.2. The chip is developed for the LHCb experiment and fulfils the requirements of the silicon vertex detector (VELO, VETO), the silicon tracker and the RICH detector in case of multi-anode photomultiplier readout. It integrates 128 channels with low-noise charge-sensitive preamplifiers and shapers. The pulse shape can be chosen such that it complies with LHCb specifications: a peaking time of 25 ns with a remainder of the peak voltage after 25 ns of less than 30%. A comparator per channel with configurable polarity provides a binary signal. Four adjacent comparator channels are being ORed and brought off chip via LVDS ports. Either the shaper or comparator output is sampled with the LHC-bunch-crossing frequency of 40 MHz into an analog pipeline. This ring buffer has a programmable latency of max. 160 sampling intervals and an integrated derandomising buffer of 16 stages. For analog readout data is multiplexed with up to 40 MHz onto 1 or 4 ports. A binary readout mode operates at up to 80 MHz output rate on two ports. Current drivers bring the serialised data off chip. The chip can accept trigger rates of up to 1.1 MHz to perform a dead-timeless readout within 900 ns per trigger. For te stabi lity and calibration purposes, a charge injector with adjustable pulse height is implemented. The bias settings and various other parameters can be controlled via a standard I2C-interface. Appropriate design measures have been taken to ensure the radiation hardness against total ionising dose effects in excess of 10 Mrad. A robustness against Single Event Upset is achieved by redundant logic

Sub-TeV hadronic interaction model differences and their impact on air showers

In the sub-TeV regime, the most widely used hadronic interaction models disagree significantly in their predictions of particle spectra from cosmic ray induced air showers. We investigate the nature and impact of model uncertainties, focussing on air shower primaries with energies around the transition between high and low energy hadronic interaction models, where the dissimilarities are largest and which constitute the bulk of the interactions in air showers.Comment: Proceedings of the 51 International Symposium on Multiparticle Dynamics (ISMD2022

Galactic Gamma Halo by Heavy Neutrino annihilations?

The diffused gamma halo around our Galaxy recently discovered by EGRET could be produced by annihilations of relic neutrinos N (of fourth generation), whose mass is within a narrow range (Mz /2 < M < Mz). Neutrino annihilations in the halo may lead to either ultrarelativistic electron pairs whose inverse Compton Scattering on infrared or optical galactic photons could be the source of the observed GeV gamma rays, or to prompt 100 MeV- 1 GeV photons (due to neutral pion secondaries) born by N - anti N --> Z--> quark pairs reactions. The consequent gamma flux (10 ^(-7)- 10^(-6) cm ^(-2) s^(-1) sr^(-1)) is well comparable to the EGRET observed one and it is also compatible with the narrow window of neutrino mass : 45 GeV < M < 50 GeV recently required to explain the underground DAMA signals. The presence of heavy neutrinos of fourth generation do not contribute much to solve the dark matter problem of the Universe, but it may be easily detectable by outcoming LEP II data.Comment: 16 pages, Latex text,in press in Astroparticle Physics 199

Forward Physics at the LHC (Elba 2010)

The papers review the main theoretical and experimental aspects of the Forward Physics at the Large Hadron Collider