HEC strange signals 1 09 Feb 2012 E.Ladygin Status of HEC spikes study in Protvino E.Ladygin, M.Kazarinov, A.Kozelov

HEC strange signals 2 Setup parameters: –ADC frequency = 250MHz –Amplifier input impedance = 50 Ohm –Gain of amplifier = 50 V/V –Trigger threshold of ADC = 39mV –Threshold recalculated to input = 15.6uA

09 Feb 2012 E.LadyginHEC strange signals 3 Tests are done: test of Pad Board with new HEC hexcel mat, which was keeping in good conditions at Dubna (Runs ) test of Pad Board with new HEC hexcel mat, which was keeping in good conditions at Dubna (Runs ) test of new HEC hexcel mat between two copper plates (Runs ) test of new HEC hexcel mat between two copper plates (Runs ) test of Pad Board between two new HEC hexcel mats in vacuum camera (pumping without baking) : test of Pad Board between two new HEC hexcel mats in vacuum camera (pumping without baking) : –Run 203 ->1 step (before pumping) –Run 205 ->2 step (short pumping ~30min) –Run 207 ->3 step (pumping ~24 h) –Run 208 ->4 step (pumping ~24+18 h) –Run 209 ->5 step (pumping ~ h)

09 Feb 2012 E.LadyginHEC strange signals 4 Signals in time (Runs ) (humidity=~30-40%, estimated, not measured) Pad Board with new hexcel mat

09 Feb 2012 E.LadyginHEC strange signals 5 Signals frequency (Runs ) Pad Board with new hexcel mat

09 Feb 2012 E.LadyginHEC strange signals 6 Signals amplitude (Runs ) Pad Board with new hexcel mat Two peaks

09 Feb 2012 E.LadyginHEC strange signals 7 Setup (Runs ) (humidity=~20%, still not measured) Hexcel mat between copper plates Teflon 5mm Hexcel Metal support Copper pad HV Gain=50 50

09 Feb 2012 E.LadyginHEC strange signals 8 Signals in time (Runs ) Hexcel mat between copper plates Stop run in 3 hours Five negative pulses with ~ an hour time step ??? My full misunderstanding

09 Feb 2012 E.LadyginHEC strange signals 9 Signals frequency (Runs ) Hexcel mat between copper plates

09 Feb 2012 E.LadyginHEC strange signals 10 Signals amplitude (Runs ) Hexcel mat between copper plates

09 Feb 2012 E.LadyginHEC strange signals 11 Pad Board between two HEC hexcel mats in vacuum camera In order to see signals from beginning and behaviour during removing water/humidity was decided to put water to hexcel (few seconds in water steam) In order to see signals from beginning and behaviour during removing water/humidity was decided to put water to hexcel (few seconds in water steam) Study of signals during pumping was not possible in my setup because HV trips appear Study of signals during pumping was not possible in my setup because HV trips appear Therefore : pumping -> filling by nitrogen -> measuring -> pumping …. Therefore : pumping -> filling by nitrogen -> measuring -> pumping ….

09 Feb 2012 E.LadyginHEC strange signals 12 Setup Vacuum camera Amplifier LV PS HV PS

09 Feb 2012 E.LadyginHEC strange signals 13 Pad Board between two HEC hexcel mats in vacuum camera (1 step: before pumping ) Signals in time (Run 203) Few positive pulses at the beginning

09 Feb 2012 E.LadyginHEC strange signals 14 Pad Board between two HEC hexcel mats in vacuum camera (1 step: before pumping ) Frequency (Run 203) Time gap ~30min (???)

09 Feb 2012 E.LadyginHEC strange signals 15 Pad Board between two HEC hexcel mats in vacuum camera (1 step: before pumping ) Amplitudes (Run 203) No peaks

09 Feb 2012 E.LadyginHEC strange signals 16 Pad Board between two HEC hexcel mats in vacuum camera (2 step: 3 times short pumping-filling by N ) Signal in time (Run 205) 1 positive signal

09 Feb 2012 E.LadyginHEC strange signals 17 Pad Board between two HEC hexcel mats in vacuum camera (2 step: 3 times short pumping-filling by N ) Examples of signals (run 205) # event A, mV More examples see in add slides

09 Feb 2012 E.LadyginHEC strange signals 18 Pad Board between two HEC hexcel mats in vacuum camera (2 step: 3 times short pumping-filling by N ) Frequency (Run 205)

09 Feb 2012 E.LadyginHEC strange signals 19 Pad Board between two HEC hexcel mats in vacuum camera (2 step: 3 times short pumping-filling by N ) Amplitude (Run 205)

09 Feb 2012 E.LadyginHEC strange signals 20 Pad Board between two HEC hexcel mats in vacuum camera (3 step: long time pumping ~24h ) Signals, amplitude, frequency (run207)

09 Feb 2012 E.LadyginHEC strange signals 21 Pad Board between two HEC hexcel mats in vacuum camera (4 step: pumping ~24+18 h ) Signals, amplitude, frequency (run208)

09 Feb 2012 E.LadyginHEC strange signals 22 Pad Board between two HEC hexcel mats in vacuum camera (5 step: pumping ~ h ) Signals, amplitude, frequency (Run 209 is ongoing) Frequency : – –11 events in h – –2 events in h – –1 event in h

09 Feb 2012 E.LadyginHEC strange signals 23 Pad Board between two HEC hexcel mats in vacuum camera Median frequency (Freq) in runs vs vacuum time (Tv)

09 Feb 2012 E.LadyginHEC strange signals 24 Hexcel with contact to a surface initiates spikes Hexcel with contact to a surface initiates spikes Hexcel with contact to HRC is “working“ much “better” Hexcel with contact to HRC is “working“ much “better” Shapes of signals are similar to ATLAS and PSPICE model which was shown last year Shapes of signals are similar to ATLAS and PSPICE model which was shown last year Removing a water from hexcel by vacuum without baking : Removing a water from hexcel by vacuum without baking : – decreases the rate of spikes (in 20 times/30h in my setup), –first view -> it does not change the shapes (?), –Amplitude (? ->low statistic, it seems to be go down ). How much time is needed to dry ATLAS? ~ times more? How much time is needed to dry ATLAS? ~ times more? Next steps ? Next steps ? Conclusion:

09 Feb 2012 E.LadyginHEC strange signals 25 Where are electrons collecting before a discharging? Where are electrons collecting before a discharging? –At the island in HRC (left)? –Inside or on surface of HEXCEL (right)? Questions for a discussion: Spark through a glue Spark through a gap HRC (+HV) HEXCEL cell wall (as conductance) HRC (GND) - -

09 Feb 2012 E.LadyginHEC strange signals 26 In both cases HEXCEL is working as conductance In both cases HEXCEL is working as conductance Conductance depends from humidity Conductance depends from humidity First case is understood, electrons can collect on island First case is understood, electrons can collect on island Second case ??? On surface, inside…. Second case ??? On surface, inside…. Questions for a discussion:

09 Feb 2012 E.LadyginHEC strange signals 27 More examples of signal shapes (No comments) More slides

09 Feb 2012 E.LadyginHEC strange signals 28 Examples of signals run203 A, mV # sample A, mV

09 Feb 2012 E.LadyginHEC strange signals 29 Examples of signals run205 # event A, mV

09 Feb 2012 E.LadyginHEC strange signals 30 # sample A, mV Examples of signals run205

09 Feb 2012 E.LadyginHEC strange signals 31 # sample A, mV Examples of signals run205

09 Feb 2012 E.LadyginHEC strange signals 32 Examples of signals run208 Ev 143 Ev 370 A, mV # sample

09 Feb 2012 E.LadyginHEC strange signals 33 Answer to Peter concerning Cu+Hexcel rate But i am still worried about the extreme low rate of your hexcel+Cu: it looks like you are here almost down to 0! You never had such a low rate before - as far as i can see. So there has to be a dramatic decline of hecspikes when going to very low humidity values. It would be nice to see the whole range for this transition... as you do now with the vacuum chamber! >>Really I did before only two tests with Cu+Hex: in last March (no signals, but it was very short test, But i am still worried about the extreme low rate of your hexcel+Cu: it looks like you are here almost down to 0! You never had such a low rate before - as far as i can see. So there has to be a dramatic decline of hecspikes when going to very low humidity values. It would be nice to see the whole range for this transition... as you do now with the vacuum chamber! >>Really I did before only two tests with Cu+Hex: in last March (no signals, but it was very short test, >>because we were sure, they should not be) and in August (we got a more/less high rate ). >>because we were sure, they should not be) and in August (we got a more/less high rate ). >>MK and me decided, that it completely depends from humidity. Humidity was very high in August. >>MK and me decided, that it completely depends from humidity. Humidity was very high in August. >> Last Cu-test in January, which I show now, happened during the changing of outside temperature, >> Last Cu-test in January, which I show now, happened during the changing of outside temperature, >>from plus/zero to strong minus. Humidity goes down, and, I think, I lost signals in 4 days due to >>from plus/zero to strong minus. Humidity goes down, and, I think, I lost signals in 4 days due to >>humidity. >>humidity. >>Now I have a hygrometer, and it shows ~8%. Outside temperature = -20C, inside =+25C. >>Now I have a hygrometer, and it shows ~8%. Outside temperature = -20C, inside =+25C. >>As I want to show in run209, but Run209 is still going to have a statistic, the rate is very low >>As I want to show in run209, but Run209 is still going to have a statistic, the rate is very low >>now (for now it's 10 events/24h).. >>now (for now it's 10 events/24h).. >>About rate goes to 0. Mikhail calculated, that we should wait few years to get on such >>About rate goes to 0. Mikhail calculated, that we should wait few years to get on such >>small area (5x5cm) a pulse comparison to ATLAS rate....!!!! Maybe we get never 0, if we have >>small area (5x5cm) a pulse comparison to ATLAS rate....!!!! Maybe we get never 0, if we have >>islands (?). >>islands (?).

09 Feb 2012 E.LadyginHEC strange signals 34 Answer to Peter about pressure/load on hexcel with PadBoard Run 160 No load Load ~100g No load Load ~100g No load Load ~100g