Speaker
Description
Summary
The PANDA experiment will make use of antiproton cooled beams of unprecedented quality, that will become available at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, featuring up to 2•10^11 antiprotons and momentum between 1.5 – 15 GeV/c.
To handle forward particle distribution due to the Lorentz boost, the apparatus is arranged in an asymmetric layout around the interaction point between antiprotons and pellet or gas jet target.
This peculiarity requires a tracking detector with a forward design and in particular an innermost Micro Vertex Detector (MVD) based on silicon devices with an innovative design in an unusual geometry. The material budget of this silicon tracker has to be minimized in view of particle momenta ranging from few hundreds of MeV/c up to several GeV/c. Besides high interaction rate asks for fast data readout being PANDA without low-level trigger selection and particle identification is planned over the full range of energies.
To cope with these requirements MVD includes four cylindrical layers in the region around the interaction point, the barrels, and six planar layers in the forward region, the disks, equipped with silicon detectors: hybrid pixel detectors in the innermost layers and double sided micro strip in the outermost layers.
In particular the mechanics integration is a challenge due to the compact volume of the MVD.
First hybrid pixel prototypes based on thinned epitaxial silicon sensors have been developed as a detector technology capable to sustain the expected radiation levels at room temperature.
Besides the handling of high data rate in a triggerless mode suggested a new non-triggered readout ASIC, for the hybrid pixel detector, that has been developed in 130 nm CMOS technology. This one provides time information via a time stamp synchronous with the 155.5 MHz global clock signal and energy information via the Time over Threshold technique. High speed serial links and early electrical to optical conversion are adopted to reduce the amount of cables and material.
Besides to cope with the limited material budget request new aluminium strips are developed for data transmission and specific busses design are under study.
Thermal power produced by the dedicated electronics, evaluated as
~ 1 W/cm^2 is removed by a water cooling system operating below atmospheric pressure mode.
For the cooling system design a material with low density, high thermal conductivity, low thermal expansion coefficient, easily machined, feasible to glue, stable at different temperatures and radiation resistant has been searched. The material which answer to all these requirements is the carbon foam: his open pore structure graphite combined with a dense graphite matrix produces a material with high thermal properties and low density. The material properties, mechanical and thermal, were studied for radiation hardness.
Besides, this material acts as mechanics support too for the pixel disks.
References:
-D. Calvo on behalf of the PANDA MVD Collaboration:
Triggerless and low mass Micro Vertex Detector for the PANDA experiment.
Nuclear Physics B (Proc. Suppl.) 215 (2011) 192-194
-D. Calvo, S. Coli, G. Giraudo, R. Wheadon and L. Zotti:
Thermal performance of carbon foams used as heat sink for the pixel MVD PANDA.
JINST 2011 6 C12015http://iopscience.iop.org/1748-0221/6/12/C12015
-D. Calvo, P. De Remigis, M. Mignone, T. Quagli, R. Wheadon,
Low mass aluminium microstrips for data transmission in the Micro Vertex Detector of the Panda experiment, , Topical Workshop on Electronics for Particle Physics (TWEPP) 2011, Wien, September 26-30. 2011
-Technocal Design Report for the PANDA Micro Vertex Detector, http://panda-wiki.gsi.de/pub/Mvd/TalkOrPaperDrafts/panda_tdr_mvd.pdf
