1. TRT workshop 25.06.20131 Argon Xenon mix stability Kramarenko Viktor Vorobev Konstantin 10/12/2015

2. TRT workshop 25.06.2013 2 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 Ar807570656080757065608075706560 CO 2 202530354017222732371924393439 O2O2 031 Component percentage Xe70 CO 2 29.52927 O2O2 0.513 10/12/2015

3. TRT workshop 25.06.2013 3 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*10 -19 ; Bending straw – 400um wire eccentricity 10/12/2015

4. TRT workshop 25.06.2013 4 Gas gain for straight straw Ar and Xe mix 10/12/2015

5. TRT workshop 25.06.2013 5 High Voltage for 25000 gas gain. Summary result for straight straw Argon HV% O2Gas mix 15120Ar - 60/40 15401Ar - 60/39/1 15803Ar - 60/37/3 1430070/30 1455170/29/1 1467370/27/3 13300Ar - 80/20 13501Ar - 80/19/1 13653Ar - 80/17/3 Xenon 15550.570.7/28.8/0.49 15650.972.1/26.9/0.9 15702.470.8/26.8/2.4 10/12/2015

6. TRT workshop 25.06.2013 6 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

7. TRT workshop 25.06.2013 7 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 ~ 100000. 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

8. TRT workshop 25.06.2013 8 Discharge point for Ar mix single straw Safety margin for Ar mix with 1 – 2% O 2. Bend straw Straight straw 10/12/2015

9. TRT workshop 25.06.2013 9 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

10. TRT workshop 25.06.2013 10 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

11. TRT workshop 25.06.2013 11 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%O2136515901570225205 80%Ar+19%+1%O2135015701510220160 80%Ar+20%O2133015401490210160 75%Ar+22%+3%O2 75%Ar+24%+1%O2140016301590230190 75%Ar+25%O2138016001570220190 70%Ar+27%+3%O2146717001670233203 70%Ar+29%+1%O2145516801630225175 70%Ar+30%O2143016501640220210 65%Ar+32%+3%O215201760 240 65%Ar+34%+1%O2151017301680220170 65%Ar+35%O2148317001710217227 60%Ar+37%+3%O215801810 230 60%Ar+39%+1%O2154017801760240220 60%Ar+40%O2151217501740238228 70.8%Xe+26.8%+2.4%O2156017701710210150 70.9%Xe+26%+0.9%O2155017201660170110 70.7%Xe+28.8%+0.5%O215601700160014040 10/12/2015

12. TRT workshop 25.06.2013 12 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