Results from Radiation Tests.

blue_ball.gif Introduction.

The nominal luminosity of LHC, 10**34 cm**-2*sec**-1, combined together with the 7 TeV beam energy will create a very hostile radiation environment in the detector experimental hall. The radiation tolerance and reliability of electronics are important issues for the CMS electronics (see Ref.1 and tutorials tut1-3 in Ref.2) including the endcap muon CSC front-end electronics.
For reminding - the neutron fluence and total ionizing dose (TID) corresponding to 10 year LHC operation at full luminosity (10 years =5*10**7 s at luminosity L = 10**34) are 6.2*10**11 n/cm**2 and 1.78 krad in ME1/1 (for En > 100 keV). This is an extreme case. For all other chambers the levels of radiation are less by at least an order of magnitude (see a test plan). For comparison the total ionizing dose resulting from the 60 MeV protons is 14 krad for the fluence of 10**11 p/cm**2. Irradiating with protons of energy in the 60 MeV to 200 MeV range is considered as a practical and effective method for testing the electronics for total dose effect (see details in the test plan and references therein).
The parameters of the EMU CSC anode front end boards vs TID have been measured in the 63 MeV proton beam at the UC Davis. A few unpowered boards also were irradiated by the neutrons in the reactor at OSU. The goal (see T.Y.Ling's talk at FNAL and Florida) was to test everything to 3 times the ME1/1 dose including also such effects as Displacement, SEU (Single Event Upset) and SEL (Single Event Latch-up) at the fluence equivalent to the neutron fluence of 2x10**12 n/cm**2 and TID effect at 5 krad. Though we only have to look for changes in the gain, noise, threshold and timing up to 5 krad we also looked for latch-up at high doses (60-70 krad).

blue_ball.gif Tests with 63 MeV protons at the UC Davis.
- March 2000 (Boards with chips CMP16E, Static Parameters only) - Results.
- June 2000 (Boards with chips CMP16F, Threshold, Gain, Slewing Time etc) - Results.

blue_ball.gif Tests with neutrons at the OSU.
- July 2000 - Results.
- October 2000 - Results.

blue_ball.gif Conclusion.

- anode front-end electronics survives the TID up to 65-70 krad and up to 1.8*10**12 n/cm**2 of neutron fluence;
- no latch-up or spikes have been observed;
- the dynamic parameters (gain, discriminator offset) are much more sensitive to a radiation than the static parameters (voltage and current draw) and they are not affected by the TID of 5 krad and beyond.

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Last modified: Thu Aug 17 14:00:00 CST 2000