1 / 10

Noise in the Readout of ATLAS LAr Calorimeters

s. Noise in the Readout of ATLAS LAr Calorimeters. Summer Student Sessions 13 August 2008 Chew Soo Hoon University Of Malaya, Malaysia (caseycsh@cern.ch) Jan Stark LPSC, Grenoble, France (stark@in2p3.fr). CERN has just announced the start-date for LHC!. 10 September 2008.

chessa
Download Presentation

Noise in the Readout of ATLAS LAr Calorimeters

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. s • Noise in the Readout of ATLAS LAr Calorimeters • Summer Student Sessions • 13 August 2008 • Chew SooHoonUniversity Of Malaya, Malaysia (caseycsh@cern.ch) • Jan Stark LPSC, Grenoble, France (stark@in2p3.fr)

  2. CERN has just announced the start-date for LHC! 10 September 2008 Unhappy channels in the ATLAS LAr calorimeters What has been going around or is going around now at ATLAS? One major issue that keeps everyone busy for these few months… Noisy channels in the detectors! S. H. Chew Noise in the Readout of ATLAS LAr Calorimeters

  3. The ATLAS LAr Calorimeters Tile extended barrel Tile barrel LArhadronic end-cap (HEC) LAr electromagnetic end-cap (EMEC) Electromagnetic Calorimeter Barrel,endcap (Pb-LAr) LArelectromagnetic barrel LAr forward (Fcal) Hadronic Calorimeter Endcap (Cu-LAr) Forward Calorimeter Endcap (W, Cu-LAr) LAr is the ‘active’ medium and the Pb, Cu and W are absorbers S. H. Chew Noise in the Readout of ATLAS LAr Calorimeters

  4. There are about 200 k readout channels in the LAr calorimeters… The signals detected by LAr calorimeters are very small (~fCor ~µV)…So, huge amplification is needed. 1 2 The bunch crossing time=25ns • But, the drift time in the LAr gap~ 450 ns 3 Hence, there is a need for the sophisticated electronics creates noises in the readout channels! Special attention is needed to solve this problem. Lists of unhappy channels have been discussing in many meetings. S. H. Chew Noise in the Readout of ATLAS LAr Calorimeters

  5. The LAr Readout Electronics in a Nutshell Ionization signal Shaped signal LAr cell electrodes collect the ionization electrons The CR-RC2 shaping filter shapes the amplified signals in 3 gains The SCA stores the signals samples in analogue format The preamplifier amplifies the current signal The trigger will select the samples to be digitized Front-end board • Front-end board is read with no input signal to detect noise. S. H. Chew Noise in the Readout of ATLAS LAr Calorimeters

  6. An Example of Lists of Unhappy Channels We wrote a program and displayed the rms values for the empty detectors in histograms to hunt for the unhappy channels! S. H. Chew Noise in the Readout of ATLAS LAr Calorimeters

  7. The list we obtained for unhappychannels • Icell layer ietaiphiregionbarrel or ecpos or neg FT slot channel gain pedrms detector • 11060 1 116 19 0 0 0 6 3 52 0 974.349 11.2143 0 • 13202 1 274 17 0 0 0 7 6 18 0 944.784 30.2519 0 • 31093 1 245 60 0 0 0 17 5 117 0 944.236 13.3464 0 • 39679 1 63 50 0 0 0 22 2 127 0 983.196 10.7274 0 • 47604 1 436 42 0 0 0 26 8 116 0 934.201 17.025 0 • 47605 1 437 42 0 0 0 26 8 117 0 916.555 17.8317 0 • 47606 1 438 42 0 0 0 26 8 118 0 934.462 17.6548 0 • 47607 1 439 42 0 0 0 26 8 119 0 951.01 17.2807 0 • 61640 1 264 5 0 0 1 2 6 72 0 967.332 21.1794 0 • 68987 1 379 13 0 0 1 6 7 123 0 934.017 17.2334 0 • 95734 1 310 43 0 0 1 21 6 118 0 965.97 10.401 0 • 113029 1 5 62 0 0 1 31 2 5 0 952.183 14.8943 0 • 145444 1 36 46 2 1 0 19 2 36 0 986.41 10.5099 0 • 153767 1 31 34 3 1 0 24 5 39 0 968.51 11.6612 0 • 178351 1 63 36 4 1 1 14 7 47 0 992.54 11.8433 0 • 184619 1 59 44 4 1 1 18 7 43 0 945.703 14.459 0 • 315531 3 4 29 0 1 0 3 7 11 1 947.216 11.1312 1 • 315570 2 7 31 0 1 0 3 7 50 1 991.372 12.198 1 • 326890 2 2 1 0 1 0 10 6 106 1 949.995 13.4252 1 • 336547 3 6 63 0 1 0 16 7 35 1 992.161 45.2964 1 • 336551 3 6 62 0 1 0 16 7 39 1 973.108 10.9021 1 • 336563 3 7 63 0 1 0 16 7 51 1 1012.84 18.8718 1 • 336655 3 4 52 0 1 0 16 8 15 1 988.347 10.6762 1 • 346250 2 4 37 0 1 0 22 8 10 1 944.161 13.5916 1 • 346266 2 5 37 0 1 0 22 8 26 1 952.744 16.1664 1 • 346302 2 7 36 0 1 0 22 8 62 1 980.425 12.5365 1 • 355842 2 4 8 0 1 1 3 8 2 1 1001.42 16.2463 1 • It agrees well with the list obtained in the meeting! S. H. Chew Noise in the Readout of ATLAS LAr Calorimeters

  8. To determine why the channels are unhappy… So, we wrote another program and obtained the plots. Number of events ADC counts Number of events Number of events two humps??? ADC counts ADC counts S. H. Chew Noise in the Readout of ATLAS LAr Calorimeters

  9. Again, we wrote another program to display the noise signal in the empty detectors Look for the noise frequency which has the same pulse pattern… The normal noise signal 10 MHz ADC counts ADC counts 30 MHz The abnormal noise signal (from the plot which has two humps) ADC counts Number of samples ADC counts Number of samples Number of samples Number of samples 19.2 MHz ADC counts Number of samples S. H. Chew Noise in the Readout of ATLAS LAr Calorimeters

  10. Conclusions • We suspected the noise is resulted from the power supply which has a frequency of ~19.2 MHz. • But, according to the electronics experts, the noise comes from the input clock somewhere in the electronics. • The answer is yet to be found out… S. H. Chew Noise in the Readout of ATLAS LAr Calorimeters

More Related