E. Bartz

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.