J.D. Dowell

Performance of a uranium/tetramethylpentane electromagnetic calorimeter

Abstract A calorimeter, consisting of uranium plates and thin liquid ionization chambers filled with tetramethylpentane (TMP) at room temperature, has been tested using electrons between 10 and 70 GeV. The essential characteristics of the liquid are discussed, including measurements of the free electron lifetime. Results on uniformity, linearity and energy resolution are described and some information on the response to hadrons has been obtained. A single TMP box containing four electrodes and a TMP position detector for electromagnetic showers have also been tested.

Multifractal analysis of minimum bias events in\(\sqrt s \) = 630 GeV\(\bar p\)p collisions

A search for multifractal structures, in analogy with multifractal theories, is performed on UA1 minimum bias events. A downward concave multifractal spectral function,f(α) (where α is the Lipschitz-Hölder exponent), indicates that there are self-similar cascading processes, governing the evolution from the quark to the hadron level, in the final states of hadronic interactions.f(α) is an accurate measure of the bin to bin fluctuations of any observable. It is shown that the most sensitive comparison between data and the Monte Carlo models, GENCL and PYTHIA 4.8 can be made usingf(α). It is found that these models do not fully reproduce the behaviour of the data.

The H1 SPACAL time-to-digital converter system

This paper describes a pipelined 1400-channel Time-to-Digital Converter (TDC) system for the H1 Scintillating Fibre Calorimeter, which will soon be installed in the H1 experiment at DESY. The main task of the TDC system is to determine the time of arrival of energy depositions, and send this information from bunch crossings that satisfy the event trigger into the H1 data acquisition system. In addition, the TDC system must monitor the timing trigger, which vetoes bunch crossings that contain too much background energy. Products of the interaction are separated from background on the basis of their different times of arrival with respect to the bunch crossing clock. For this monitoring the TDC system uses automatic on-board histogramming hardware that produces a family of histograms for each of 1400 channels. The TDC function is performed by the TMC1004 ASIC. The system digitises over a range of 32 ns per bunch crossing with 1ns bins and a precision of 1ns. Because of the way the TMC1004 is designed, it is possible to vary the size of the bins between 0.6 ns and 3 ns by trading off measurement range for bin size. The system occupies two 9U VME crates.<<ETX>>