TOTEM Collaboration Meeting June 2007 Total Cross Section, Elastic Scattering and Diffraction Dissociation at the LHC GEM and VFAT: H8 Test results Half Equipped Detector NoiseTest T2 Hybrids Noise Results H8 System Special thanks to Gueorgui, Emilio and Frederic that give us the possibility to acquire some data during the last test weeks! TOTEM Collaboration Meeting June 2007

TOTEM Collaboration Meeting June 2007 Noise Tools THRESHOLD SCAN: Fast and full channel qualitative analysis PULSE CALIBRATION SCAN: Quantitative analysis The new fitting procedure works better than the previous one. Thanks! During the February tests we verified for pads that a measure of the MEAN Y and RMS Y of all channel output of the threshold scan nearly reflects the behavior of the single channel pulse calibration scan. TRIGGER S BIT Very fast analysis In the last test weeks we used mainly Threshold and the S BIT tools for the crash probability during the acquisition TOTEM Collaboration Meeting June 2007

Threshold Scan Results Half Equipped Detector Threshold Scan Results We equipped a TripleGEM with 2 VFAT for Strips and 7 for pads. We didn’t connect the HV to the chamber in all the following tests. * We changed this VFAT for readout problems (no sense output) Pads DVth 5%~[5-30] Int Strips DVth 5%~20 Ext Strips DVth 5%~35 We have obtained this lowest noise situation: -shielding the chamber. -shielding the strips VFAT-TB cables. -making a direct gnd connection between strips Hybrid gnd and Chamber gnd We tried also, without any improvement, to: -shielding the HV distribution board -connecting to gnd the last gem foil VFAT in the middle: It has VFATs on strips in one side and 50 ohm termination in the other side TOTEM Collaboration Meeting June 2007

Threshold Meaning for GEMs… From: FEDCTOT05_Specification 0.045fC ~ 280 electrons MIP: first ionization cluster We have then: Vth=30 -> ~8.4k electrons Vth=50 -> ~14k electrons Dynamical Range = 256 -> ~72kel. m 10Gev in Ar-CO2 (70-30) @ stp Mean ~ 27 Most Probable Value ~ 13 RMS ~ 30 30 As an example, to have this working range we need a TripleGem Gain of 1.2k (if I didn’t stupid mistakes !?!) 250 50 TripleGEM GAIN Effects TOTEM Collaboration Meeting June 2007

Low Voltage Power Supply Readout Configuration: Only one VFAT in pad sector PS12 Mean y @ 5% RMS y Signal Range 5% [A] CAEN FLOATING POWER SUPPLY (+5V, +2.5V, +2.5V) 13.96 5.15 10-25 [B] CAEN FLOATING POWER SUPPLY (only 5V, 2.5V supplied from Regulators on TB) 12.69 7.63 10-35 [C] LOCAL LOW VOLTAGE PS (only 5V , 2.5V supplied from Regulators on TB) GND connected to Table GND 12.43 6.2 [A] [B] [C] [5%] [1%] [A] [B] [C] Be careful because there are different scale. (I’m sorry..) We leave this local power supply because we were interested to study the half equipped detector with this one. Managing on the chamber (for example with shields) we restore a good level of noise We achieved a good configuration with the local power supply, but it seems that having the three power supply lines separated could be better (from pulse calibration scan outputs). TOTEM Collaboration Meeting June 2007

TOTEM Collaboration Meeting June 2007 Shielding Test Over Strips Connection The first Shielding tests were made on partial equipped detector looking at the S1 Bit and collecting then some Threshold and Calibration Scan Sigma Erf Fit behavior for partial equipped detector (2/3 VFTAs) BACK [A]: Without Shields VFAT on Pads (PS12) and Ext Strips (SS03) [B]: With Chamber’s Shields VFAT on Pads (PS12) and Ext Strips (SS03) [C]: With Chamber’s and VFAT-TB cables’ Shields VFAT on Pads (PS12) , Ext Strips (SS03) and Int Strips (SS04) [A] [B] [C] To obtain a good level of noise we have: Shielded the chamber (Top and Rear) Shielded the VFAT-TB Cables PADS EXT STRIPS INT STRIPS TOP Over Strips Connection To obtain the best noise level, with the half equipped detector, we added also a shield over the connectors zone. WE HAVE A LOT OF NOISE REDUCTION SHIELDING THE CHAMBER, BUT TO DEFINE WHICH SHIELD IS REALLY USEFUL WE NEED TO WORK IN A MORE CLEAN CONDITION….see VFAT-TB cables effects. TOTEM Collaboration Meeting June 2007

HALF EQUIPPED DETECTOR Noise Test Observations Changing the threshold of VFATs that are not scanned, you see effects on the scanned VFAT. Not Scanned VFAT Threshold: Pads=50 Strips=50 Not Scanned VFAT Threshold: Pads=30 Strips=50 Threshold Scan on External Strips We can see this injection of noise from the scanned VFAT into the other strips/pads looking at the cumulative plots Pads [Th=50] Threshold Scan on External Strips Internal Strips [Th=50] Large Pads under External Strips TOTEM Collaboration Meeting June 2007

HALF EQUIPPED DETECTOR Noise Test Observations STRIPS THRESHOLD SCAN We found for strips situation in wich all channels seem to move nearly together. External Strips TOTEM Collaboration Meeting June 2007

Some example of VFAT-TB cable connection (moving, replacing) effects THRESHOLD SCAN ON THE EXTERNAL STRIPS EXTERNAL STRIP CUMULATIVE NOISE PADS CUMULATIVE NOISE INTERNAL STRIP CUMULATIVE NOISE Run 200551 We change one VFAT on Pads and we move Vfat-TB Cables HALF EQUIPPED DETECTOR Run 200559 We change the twisted Vfat-TB Cable for strips with the green one Run 200567 A next step could be to make all these noise studies in a more clear and simple situation than in the “aquarium” (on a table for example, where should be easiest the control of gnd, cable, etc etc). TOTEM Collaboration Meeting June 2007

VFAT POWER SUPPLY MONITORING AVDD 2.5V Analog S1 DVDD 2.5V Digital ~ 5% of variation in an/dig power supply lines We tried to supply the chip with bigger cables directly from the TB, without any improvement. We change also the local power supply with the CAEN Floating one, but we found the same behaviour. TOTEM Collaboration Meeting June 2007

TOTEM Collaboration Meeting June 2007 Half Equipped Detector Number of Channel ON Only one Pads Sector On (Threshold scan on Pads) Pads [fixed Threshold 50] (we have a lot of noise in the pads in correspondence with the ext strips) Only one Strips Sector On (Threshold scan on Strips) Internal strips [fixed Threshold 50] Only One Pads and One Strips On (Threshold scan on Strips) Threshold scan on External strips The histograms are relative to 1k of events TOTEM Collaboration Meeting June 2007

TOTEM Collaboration Meeting June 2007 Half Equipped Detector: External Strips Threshold Scan – Scan Evolution Only 1 2 3 TOTEM Collaboration Meeting June 2007

TOTEM Collaboration Meeting June 2007 Hybrids TEST: Comparison between hybrids V2 with and without separate An. and Dig. GND DIGITAL AND ANALOG GND CONNECTION ON THE CHIP VFAT NOT PLUGGED ON GEM: Results from Pulse Calibration Scan: -Digital/Analog GND CONNECTED on the chip Sigma of the ERF fit between 4 and 6 -Digital/Analog GND NOT CONNECTED on the chip Sigma of the ERF fit between 1.5 and 2 These results are in contrast with the VFAT test results obtained in lab. Possible explanation of this inconsistency could be: -Different GND Configuration (The various GND configuration are listed in the following pages). The GND configuration in the test beam zone it is not so good as could be in lab. -Different Cable length between VFAT and Transition Board -… VFAT PLUGGED ON GEM: No evident benefits on having the Digital/Analog GND NOT CONNECTED on the chip (in some configuration seems also to be worse). Anyway, we don’t have an accurate investigation on this point because we have understood that the final hybrid should be, without any chance of modification, with An-Dig Connected. TOTEM Collaboration Meeting June 2007

TOTEM Collaboration Meeting June 2007 H8 System – I2C FEC errors code: 250,210,.. Normally we have found difference between write and read like … 0 1 0 0 … … 0 0 1 1 … write read Frederic put a patch that permit to us to use GUIDebugger and VFATDebugger. It could be better if we could also upgrade the acquisition Software in the same way, i.e. to try again (and not crash) for n times if it find these kind of errors. Control Loop: Problems disappeared when Geourgui swapped the two DOH FEC GREEN LED forever!! TOTEM Collaboration Meeting June 2007

ZERO DATA FILES (only for the monitor!) H8 System ZERO DATA FILES To run again : /home/xdaq/daqkit/TriDAS/daq/itools/packages/fedkit/fedkit_dump_receiver.orig -r 0 -l 0 Sucessfully opened a FEDkit receiver with FPGA version 0x3f00002a Failed while trying to set receive pattern. Reverting to default. K 0x50c800c700c600c5 . 0x000000000000f7f7 . 0x0000000000000000 . 0x000000000000022b Data File Start with the right header Monitor Output OK! To run again : /home/xdaq/daqkit/TriDAS/daq/itools/packages/fedkit/fedkit_dump_receiver.orig -r 0 -l 0 Sucessfully opened a FEDkit receiver with FPGA version 0x3f00002a Failed while trying to set receive pattern. Reverting to default. . 0x000000000000f7f7 . 0x0000000000000000 K 0x50c800c700c600c5 Data File Start with the wrong header (for OptoRX buffer problems) Monitor Output ZERO DATA FILES (only for the monitor!) We solve this problem turning off/on the power supply of the optoRx but possible solution cuold be: 1- Ask to the monitor software to search for the right header and packet length 2- Ask to the acquisition software to send a “clear buffer”command before the acquisition start TOTEM Collaboration Meeting June 2007

Possible very first steps to done on noise analysis Refine the gnd configuration in H8. We have to find the Paul’s result for the VFATs not plugged on the detector. Realize a simple and temporary horseshoe card (only for the powering and grounding the VFATs on the detector). We could try to supply the chip without passing from the TB. Repeat some of the tests done in a more clean situation (lab and/or table in H8). We have for example to accurately check: Which shield on the chamber/cables is really useful. The VFAT-TB cables effects, to avoid mistakes in the interpretation of data. TOTEM Collaboration Meeting June 2007