B. Harrop

The silicon vertex detector for the super B factory

The silicon vertex detector (SVD2) of the Belle experiment at KEK (Tsukuba, Japan) is currently close to its limits in terms of the occupancy of the innermost layer and the readout dead time. In order to cope with further increase in luminosity, different levels of upgrades are proposed: small improvements are possible in the short term by tuning the current system at the cost of signal-to-noise and crosstalk. In 2007, the two inner layers of the SVD2 will be replaced by similar detectors with faster readout electronics (SVD2.5) and in the long term, a major upgrade of the full silicon vertex detector (SVD3) is envisaged for the KEK Super B Factory. These upgrade scenarios will be discussed in detail from the hardware point of view along with the options under study.

Studies of PLT-type single-crystal diamond pixel detectors

The Pixel Luminosity Telescope (PLT) is a dedicated luminosity monitor, presently under construction and planned for installation during the next CMS opening, for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC). It measures the particle flux in an array of sixteen telescopes each consisting of three layers of pixel diamond detectors. The PLTs single-crystal CVD diamonds are bump-bonded to the PSI46 pixel readout chip - the same readout chip used in the silicon pixel system in CMS. Final hardware and software components have been assembled at CERN. The performance with has been measured this year in beams at the CERN PS, as well as the test beam facility at Fermilab. With respect to charged particle tracking, we also measured the Lorentz angle in a magnetic field at the CERN SPS. We present the results of these studies for the final system.

Resolution studies of single-crystal CVD diamond

The Pixel Luminosity Telescope (PLT) is a dedicated luminosity monitor, presently under construction, for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC). It measures the particle flux in three layers of pixel diamond detectors that are aligned precisely with respect to each other and the beam direction, utilizing simultaneously performed particle track position measurements. The PLTs single-crystal CVD diamonds are bump-bonded to the PSI46 pixel readout chip — the same readout chip used in the silicon pixel system in CMS. Single-crystal CVD diamond pixel detectors have many attributes that make them desirable for use in charged particle tracking in radiation hostile environments such as the LHC. They are expected to withstand the radiation near the beam pipe over several years at full LHC luminosity with a modest loss of pulse height and no increase of leakage currents. In order to further characterize the applicability of diamond technology to charged particle tracking, the intrinsic spatial resolution of single-crystal CVD diamonds was measured using a high resolution beam telescope developed at the University of Zurich. We present the results of these studies.

Diamond detectors for radiation and luminosity measurements in CMS

The Beam Conditions Monitor (BCM) provides fast, relative measurements of particle fluxes for use in the safety systems of CMS. It uses a set of Chemical Vapor Deposited (CVD) diamond diodes. Sudden, order of magnitude changes in the BCM readout issue non-maskable LHC beam aborts. Dangerous irradiation trends on longer timescales translate into automatic detector interlocks and injection inhibit. Operators in the LHC beam and CMS detector control room obtain and display real time (1Hz) readout of flux measurements from the BCM subsystem. The beam radiation monitoring system also provides an independent measurement of the beam luminosity. The next generation luminosity detector, called the Pixel Luminosity Telescope (PLT), is based on pixelated monocrystalline diamond detectors. They provide a fast occupancy information and allow particle tracking near the interaction point to distinguish trajectories originating from the proton-proton collision point and those parallel to the beam pipe. We present the use case of diamond detectors for beam radiation monitoring in CMS and first measurements of 150 GeV/c π+ particle tracks in three layers of pixelated diamond detectors. The PLT after installation in 2010 will be the largest utilization of diamond instrumentation in High Energy Physics.

Level-1 silicon vertex detector trigger at Belle

We present a newly developed fast trigger system that uses the silicon vertex detector (SVD) for the Belle experiment at the KEKB energy-asymmetric e/sup +/e/sup -/ collider. It is designed to issue the trigger with a latency of 1.85 /spl mu/s for the Belle central trigger system (GDL). The primary purpose of the SVD trigger is to reduce beam-induced background events by requiring tracks that come from the interaction point. The system receives trigger signals from VA1TA front-end integrated circuits, which read out signals on the silicon-strips. SVD tracks are constructed with them in combination with the trigger information of the central drift chamber (CDC), which is located outside the SVD. Performance of the SVD trigger is evaluated with collision data.

The Belle L1.5 trigger

During the summer shutdown of 2003 the new silicon vertex detector SVD2 was installed in Belle at the KEK-B factory in Tsukuba, Japan and started to take data in October 2003. It provides important improvements in the tracking capabilities and adds new trigger functionality. In addition a new hardware trigger level 1.5 was designed and installed that takes advantage of the digitized SVD hit data. The improvement in the Belle trigger system is important to deal with the increasing luminosity and higher beam currents of the KEK-B collider. The design of the level 1.5 trigger system is reviewed and results from the data taking are presented.