PADI status Mircea Ciobanu 11 th CBM Collaboration Meeting February 26-29, 2007, GSI FEE1 PADI

Outline  Status of the PADI: - electrical measured parameters - results in the beam test for rate evaluation - preparations for beam test of  - preparations for beam test of  t  What to do next  Summary and Outlook

Measurement phase of PADI Electrical measurementsElectrical measurements Measurements together TACQUILA3Measurements together TACQUILA3 Connection with a Diamond Detector to test inConnection with a Diamond Detector to test in beam the rate capability and the stability of the system in real conditions. Design phase of PADI Comparison NINO_FEE - FEE3Comparison NINO_FEE - FEE3 Simulations for new Preamplifier Discriminator PADISimulations for new Preamplifier Discriminator PADI

The PADI together with a SC Diamond (4 pixels) detector PADI test PCB LVDS-PECL Converter PCB Interface PCB +5V,GND,THRconnections Time Output's LAN-K5 cable ~2.1m ~2.1mConnection's with with SC Diamond Pixel Detector

Rate Histogram for 110 spills (the beam has a fixed position) Integral number of counts : of counts : pixel # x10 6 pixel # x10 6 pixel # x10 6 average: x10 6 individual error ~ +/- 0.2% September , 2007 Dresden

 Summary of tests The PADI design was successful tested, all channels are operational. The PADI design was successful tested, all channels are operational. The connection of PADI with our TAQUILA3 Data Acquisition system works properly. The first results indicate:   Time [ps]< 10   Gain ~ 60   Bandwidth [MHz]~ 180   Linear range [mV]~ -5 to 5   CTRR [dB]~   CMRR [dB]> 40   Input impedance [  ]~   Power [mW/Ch]~ 31   The PADI design was successful tested, together with a 4 pixels SC diamond detector. The system was stable in under beam conditions.   The AC transmission measurements shows a possible instability of the PADI preamplifier cell.   The connection of PADI with the detector is critical: the line used should have a flat frequency characteristic of the impedance to avoid particularly resonances.   If the input signal is near the threshold limit, the discriminated output signal has a very low width (~1ns). We have tried to transport such signals through a 110  twisted pair LAN-K5 cable and the channel rate limit was 1.5 x 10 8 hits/s.

Technological details for the direct bonding of the PADI ASIC on the pcb. In the FOPI new START system we will test two variants: in air bond-wires with mechanical protection and Glob Top (epoxi compound) protection.

The next step: Redesign of PADI We started from the NINO1-CERN ASIC schematics used for the ALICE ToF. For a simple comparison between time over threshold and Q measurement for WALK correction, we have added an supplementary buffer block to obtain both information's: time and energy. The whole design was matched for CMOS 0.18  m technology. We started from the NINO1-CERN ASIC schematics used for the ALICE ToF. For a simple comparison between time over threshold and Q measurement for WALK correction, we have added an supplementary buffer block to obtain both information's: time and energy. The whole design was matched for CMOS 0.18  m technology.  Very high time resolution  Cope with pads and strips RPC's  Higher Integration  Lower Power consumption  Lower price per channel PADI Design goals Redesign goals 1. Four channels instead of three. 2. The increase of closed loop stability. 3. The increase of bandwidth of the preamplifier cell. The redesign work can be finished at the end of May and the layout at the end of July.

Preamplifier: AC equivalent diagram  t ~√Nd /(As*√BW) September 20-22, 2006 Strasbourg

Outlook  To make tests together with the standard RPC detector.  We are ready to connect the PADI test plate with the new generation of TAC.  It is the necessary to evaluate QDC versus ToT methods for charge evaluation before the redesign of PADI!  To redesign PADI for a 4 channel variant, and to take into account the following: - Special simulations of the system stability to be above the suspicious of instability. - The increase of PADI preamplifier - discriminator actual bandwidth is a hard task, but we will try to evaluate the limit of the used architecture. We will focus on the reduction of the parasitic capacitances present at the preamplifier input and output ports which in this moment dominates.

We acknowledge the support of the European Community- We acknowledge the support of the European Community- Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (HadronPhysics, contract number RII3-CT ).