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SSD News and Update - October 16th, 2007

Get the latest news and update on the SSD technology presented by Jim Thomas from Lawrence Berkeley National Laboratory. Find out about recent progress, activities, and the need for upgrades to improve performance and reliability.

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SSD News and Update - October 16th, 2007

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  1. SSD News and Update presented by Jim Thomas Lawrence Berkeley National Laboratory October 16th, 2007

  2. The SSD in a Nut Shell • Technology ( 4 cm wafers at 23 cm radius) • 30 m x 750 m resolution at 23 cm radius (compare TPC at 1.5 x 1.5 mm) • Thin – 1% radiation length • Crossed strips at 35 mrad • DAQ rate limited to 200 Hz

  3. The SSD was removed last summer Cooling problems – led to overheating of modules Response: shut down modules on ends to lower heat load Problems were identified during the run

  4. Recent progress and activities • We have access to the old SVT lab … it is now the SSD lab • Thanks to Mike Levine (lab space at BNL is very hard to find) • Nantes test-bench now working at BNL • Did not work on the first trip … the usual sort of soft/hardware issues • Tested each ladder after the run to compare performance • Seven ladders were not operational in run 7 • We can fix 4 of these. Capacitor replacement, and improving the cooling system. (2 from caps, 2 from cooling) • Ladders 6,7,8 we don’t know what is wrong, yet. 6 and 7 were dead in Cu–Cu and were also dead before run 7. Ladder 8 had erratic behavior on the test bench. Data was noisy. Presumably these are true hardware failures. • The other thirteen • 6 ladders behaved normally • 2 ladders are ‘perfect’ • 4 of these ladders had JTAG errors on the Bias return, so forced bias settings, but otherwise were ‘perfect’ • 6 ladders had/have one bad module (otherwise OK) • We assume that the bad modules cannot be replaced so this is our legacy • One ladder had high noise levels during the run. Cause not yet identified. The distribution of bad elements suggests that all four super-modules should go back to Nantes for expert repair.

  5. Level 2 • Level 2 abort did not work during run 7 • L2 test bench set up on the 3rd floor of the South Platform • Use existing RDO boxes and STAR DAQ • No ladder needed; the problem is in the readout, not the data. • L2 repairs • Mike L. had been able to reproduce the error with the test apparatus • Software problem; probably not a hardware problem • It’s a compatibility problem. Mysterious error messages. Error moves around … moved from board to board or fiber to fiber. • Tested RDOs one by one. Switch fibers, etc. • More work required to fully characterize the problem • Confucious says “Looks like two things are wrong at the same …” • Once a repair is achieved … • We need to verify this repair and the other repairs by running the SSD in the upcoming runs

  6. We not only want to run the SSD again but upgrade it, too • It’s a beautiful detector – but it needs to be upgraded to meet the DAQ 1000 era specifications • It will deliver incremental improvements in the reconstructable yield of the strange mesons and baryons • K, , ,  • It will have improved single-track high pT resolution • It will improve the invariant mass resolution for resonances and spectra measurements • It is thin – and so can improve signal to noise ratio for non-photonic electrons • It is essential for the HFT Upgrade (~$16M)

  7. The SSD Improves Mass & Spatial Resolution • Jonathan’s thesis work for Cu-Cu at 200 GeV • Improved DCA resolution • Improved S/N for K0

  8. The SSD Delivers High PT Momentum Resolution • TPC pointing resolution without a vertex constraint • ½ field (blue), full field (red), and full field with the SSD (pink) The SSD doubles the high pT resolution on a track by track basis

  9.  Invariant Mass Resolution • Qinghua’s simulation of high pT lambda’s with and without the SSD

  10. The Upgrade • Upgrade to DAQ 1000 Specs • Control Board • ADC Board • RDO board (not shown) • Si Wafers remain the same • Mechanical structures remain the same • Cooling and conventional systems also need an upgrade to improve reliability

  11. Mike’s dead time calculation • It is desirable to add buffers to the existing readout • Can be done at the FPGA level • 8% dead time at a true rate of 500 Hz, or < 20% at 1 kHz

  12. Conclusion & a request for additional ideas • The Upgrade proposal is due soon. Not yet done. • Mea Culpa • The SSD delivers improved pointing resolution and invariant mass resolution • It can do this on a track by track basis • Without resort to a vertex constraint • It works for single tracks but also in p-p, minBias, and UPC collisions where the vertex is not well defined • It extends our scientific program • In addition to being a essential ingredient for the HFT • Any other good ideas? P.S. Money has to move to France, soon. Not for the upgrade but to show good faith on past debts.

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