TRT workshop Argon Xenon mix stability Kramarenko Viktor Vorobev Konstantin 10/12/2015

TRT workshop Research program 1.Gas amplification. 2.Point of discharge. 3.Maximally possible safe mode under varied conditions: the displacement of signal wire, γ irradiation, α particles. 4.Long-term work with real TRT module, under the irradiation. Table of the gases was investigated: C o m p o n e n t p e r c e n t a g e Ar CO O2O2 031 Component percentage Xe70 CO O2O /12/2015

TRT workshop Setup for investigations gas gain and safety margin on single straw CAEN HV Gas Attenu ator Amplif ier Dual discrimin ator Dual counter Preamp Fe 55 /Am 241 Low level threshold High level threshold 61k 1k Gas gain = I × w / (N Low threshold × ‹E› × q) w for Ar ~ 27 eV; for Хе ~ 24 eV; q – 1.6* ; Bending straw – 400um wire eccentricity 10/12/2015

TRT workshop Gas gain for straight straw Ar and Xe mix 10/12/2015

TRT workshop High Voltage for gas gain. Summary result for straight straw Argon HV% O2Gas mix 15120Ar - 60/ Ar - 60/39/ Ar - 60/37/ / /29/ /27/ Ar - 80/ Ar - 80/19/ Ar - 80/17/3 Xenon /28.8/ /26.9/ /26.8/2.4 10/12/2015

TRT workshop Setup for the discharge point study for single straw CAEN HV Gas Attenu ator Amplif ier Dual discrimin ator Dual counter Pream p Fe 55 /Am 241 Low level threshold High level threshold 61k 1k 10/12/2015

TRT workshop Barrel type 2 №13, 520 straw Gas Ar and Xe mix with close gas system. Two X-ray 40 kV, 5 uA Current of ionisation 22 – 70 nA/cm straw for GG ~ Trip of each HV unit 1mA on 128 straw, work current 0.7uA for H/V unit X-rays 40kV CAENNCAENN CAENNCAENN CAENNCAENN CAENNCAENN Barrel Setup for investigation safety margin on real TRT unit 10/12/2015

TRT workshop Discharge point for Ar mix single straw Safety margin for Ar mix with 1 – 2% O 2. Bend straw Straight straw 10/12/2015

TRT workshop Ar mix. Instability of Ar gas mix 70/30 without O 2 Argon long time measurement with BARREL Insufficient level of safety margin 10/12/2015 Barrel Ar Long-term test For each gas mix > 100 hours under 40keV X-rays

TRT workshop Gas gain and discharge issues for Xe Xe Safe margin Insufficient level of safety margin 10/12/2015 Barrel Xe Long-term test For each gas mix > 100 hours under 40keV X-rays

TRT workshop Safety margin summary for Ar and Xe mix Gas mix Gas gain Discharge point bend straw Discharge point bend straw alfa Safety margin bend straw Safety margin bend straw alfa 25000VVVV 80%Ar+17%+3%O %Ar+19%+1%O %Ar+20%O %Ar+22%+3%O2 75%Ar+24%+1%O %Ar+25%O %Ar+27%+3%O %Ar+29%+1%O %Ar+30%O %Ar+32%+3%O %Ar+34%+1%O %Ar+35%O %Ar+37%+3%O %Ar+39%+1%O %Ar+40%O %Xe+26.8%+2.4%O %Xe+26%+0.9%O %Xe+28.8%+0.5%O /12/2015

TRT workshop Conclusion AR mixtures 60-80% with oxygen content more than 1% are stable from the point of view of safety and stable long-term work under the conditions of high luminosity ATLAS. This statement is correct for the working gas gain. Of course, work with the large gas gain reduces safety margin level. 10/12/2015