M. Lindgren

The CDF Plug Upgrade Electromagnetic Calorimeter: Test Beam Results

Abstract The CDF Plug Upgrade calorimeter, which fully exploits the tile–fiber technique, was tested at the Fermilab meson beamline. The calorimeter was exposed to positron, positively charged pion and positive muon beams with energies in the range of 5– 230 GeV . The energy resolution of the electromagnetic calorimeter to the positron beam is consistent with the design value of 16%/ E ⊕1% , where E is the energy in units of GeV and ⊕ represents sum in quadrature. The non-linearity for positrons is studied in an energy range of 11– 181 GeV . It is important to incorporate the response of the preshower detector, the first layer of the electromagnetic calorimeter which is readout separately, into that of the calorimeter to reduce the non-linearity to 1% or less. The energy scale is about 1.46 pC / GeV with HAMAMATSU R4125 operated typically at a gain of 2.5×10 4 . The response non-uniformity over the surface of a tower of the electromagnetic calorimeter is found to be about 2% with 57 GeV positrons. Studies of several detailed detector characteristics are also presented.

SHOWER MAXIMUM DETECTOR FOR THE CDF PLUG UPGRADE CALORIMETER

Abstract We describe a detector designed to measure the position of electrons and photons in the new CDF Plug Upgrade Calorimeter. The detector comprises 6400 individual scintillator strips placed at the shower maximum location of the electromagnetic calorimeter section and coupled to wave-length-shifting fibers read-out by multi-anode photomultipliers. We describe the design criteria, the R&D studies that led to the choice of scintillator and fiber, the mechanical assembly, and the quality control tests during production and assembly of the detector elements.

A High speed, wide dynamic range digitizer circuit for photomultiplier tubes

Abstract A circuit has been designed for digitizing PMT signals over a wide dynamic range (17–18 bits) with 8 bits of resolution at rates up to 53 MHz. Output from the circuit is in a floating point format with a 4 bit exponent and an 8 bit mantissa. The heart of the circuit is a full custom integrated circuit called the QIE (Charge Integrator and Encoder). The design of the QIE and associated circuitry reported here permits operation over a 17 bit dynamic range. Test results of a multirange device are presented for the first time.

Intercalibration of the longitudinal segments of a calorimeter system

Three different methods of setting the hadronic energy scale of a longitudinally segmented calorimeter system are compared with each other. The merits of these methods have been studied with testbeam data from the CDF Plug Upgrade Calorimeter. It turns out that one of the (commonly used) calibration methods introduces a number of undesirable side effects, such as an increased hadronic signal nonlinearity and trigger biases resulting from the fact that the reconstructed energy of hadrons depends on the starting point of their showers. These problems can be avoided when a different calibration method is used. The results of this study are applied to determine the e/h values of the calorimeter and its segments.

A scintillating fiber detector for electron and photon identification at high luminosity colliders

Abstract We report on the construction and first operating experience of a novel detector designed to measure with high accuracy the spatial position of charged particle trajectories and of electromagnetic showers from electrons or photons. This position detector was constructed of two layers of 2 mm thick scintillating fibers with a 15° angle between layers. The photon readout used a newly developed multianode photomultiplier. The device was inserted in a prototype electromagnetic calorimeter for the CDF collaboration and studied at a Fermilab test beam facility. The position detector yielded a spatial resolution for electromagnetic showers of 400 μm for 100 GeV electrons.

Tests of a third generation multianode phototube

Abstract We report on results of tests of the 16-channel Hamamatsu R5900-M16 photomultiplier tube for gain uniformity and stability, pixel uniformity, linearity, cross-talk, and quantum efficiency. These parameters are essential to our application; i.e., the read out of signals which are generated by the passage of ionizing particles through the scintillating strips of an electromagnetic shower maximum detector and which are carried to the photodetector by optical fibers. In all respects the R5900-M16 tube performance is found to be superior to that of earlier generations of multianode photomultiplier tubes.

A preshower detector for the CDF Plug Upgrade: test beam results

A preshower detector consisting of plastic scintillating plates with optical-fiber readout was tested at the Fermilab meson beamline. The detector was placed at a depth of about 1.5X0, followed by an electromagnetic and hadronic calorimeter, and exposed to positron, positively charged pion and positive muon beams with energies in the range of 5–227 GeV. Multianode phototubes, HAMAMATSU R5900-M16, were used for the photon readout. The efficiency for detecting two minimum ionizing particles with noise occupancy of <1% was 90–100% for gains of (1–4)×105. It was also found that by requiring an appropriately large signal in the preshower detector, the rate of charged pions depositing a large fraction of energy in the electromagnetic calorimeter could be reduced by a factor of 1.4–2.0 (1.4–2.8) while keeping 95% (90%) efficiency for positrons.

New limit on CPT violation

A search for antiproton decay has been made at the Fermilab Antiproton Accumulator. Limits are placed on fifteen antiproton decay modes. The results are used to place limits on the characteristic mass scale m(X) that could be associated with CPT violation accompanied by baryon number violation.

SMQIE: a charge integrator and encoder chip for the CDF Run II Shower Max detector

The Technical Design Report for the CDF II Detector calls for the development of an imbedded two-dimensional position sensitive detector sandwiched inside the electromagnetic calorimeter and placed at the shower maximum. The purpose of this detector is to aid in the identification of electrons and photons, to separate photons from /spl pi//sup 0/s, and to help identify electromagnetic showers. This detector is called the Shower Max. In order to achieve CDFs goals for resolution, timing, power and economy, as well as to fit into the available space, a full-custom integrated circuit was required for the project the SMQIE. The SMQIE has been fabricated in a 1.2 /spl mu/m CMOS process using vertical NPN transistors in critical areas. It operates without deadtime. Its QIEs have eight ranges and an overall dynamic range of 13 bits. Its FADCs have a 5-bit resolution with a nominal LSB of 31.25 mV. Its Level 1 Trigger delays are 42 beam crossings or approximately 5.5 /spl mu/s. Its data buffers hold up to four events, each of which can consist of four time slices. Finally, the chip accepts a maximum input charge up to 150 pC with a minimum resolution of 15 fC.

Search for muonic decays of the antiproton at the Fermilab Antiproton Accumulator

A search for antiproton decay has been made at the Fermilab Antiproton Accumulator. Limits are placed on six antiproton decay modes which contain a final-state muon. At the 90% C.L. we find that tau/B(mu gamma) > 5.0 x 10^4 yr, tau/B(mu pi0) > 4.8 x 10^4 yr, tau/B(mu eta) > 7.9 x 10^3 yr, tau/B(mu gamma gamma) > 2.3 x 10^4 yr, tau/B(mu K0S > 4.3 x 10^3 yr, and tau/B(mu K0L) > 6.5 x 10^3 yr.