1. Light and charge collection with a new Micromegas-TPC Light and charge collection with a new Micromegas-TPC Leila Ounalli Neuchâtel University CHIPP workshop on Detector R&D 11-12 June- University of Genova Ionisation Scintillation

2. 2 A 2 2/1  1 0   T  0 2 2 0 0 0,  m M g g MZEG F V GT Double beta decay and the Standard Model (SM) 122):(,)(,)  AZAZee ee   - e d(n)u(p) - d(n) u(p) e e W W e d(n)u(p) e - e W d(n) u(p) W e - e If ββ0 exists: Neutrinos are Majorana type

4. The EXO detector

5. Why we need a good energy resolution? Arbitrary units Réaliste Optimiste 2.48 Q ββ [Mev] Realistic Optimistic

6.  = 3.3% @ 2.48 MeV EXO: a strong anti-correlation observed between scintillation and ionization signals Combing both Scint & ioniz  ) S+I = 1.7 % Ionization only  ) I = 4.8 % Scintillation only  ) S = 10.3 %

7. Micromegas « Compact » The Micromegas-TPC The Micromegas-TPC 1mm spacers Woven wires http://www.bopp.ch/ (gamma, RX, UV …) e- Cathode Grid Amplification (> 50  m) Micromesh E d ~ 200V/cm E a ~ 40-100kV/cm Anode Conversion + Drift

8. The Neuchâtel mini-TPC prototype miniTPC(10X20cm) The source position. max of count @ d C-g =18cm E drift The drift electric field: E d = 200 V.cm -1.bar -1 The gap dimension (d grid-anode ): (75-100-250 µm) High pressure + low voltages The quencher choice and %: - Xe + (CF 4, isobutene): double beta decay - CF 4 + (Xe, Ar): solar @ low E

9. A higher pressure requires a larger gap 10 4 @ 4 bar 75 µm Gas:P10, E d =200 V.cm -1.atm -1 P={1(black), 2(red), 3(green), 4(blue)} atm 250 µm

10. How to improve the charge collection in Xe? A small CF4 addition is sufficient

11. increases the electron drift velocity in Xe. CF 4 is the best additive for Xe CF 4 addition: reduces longitudinal and transversal diffusions. ← improves the charge collection. P: 1.00 atm, E d =200 V.cm -1.atm -1, Gap: 100 µm ■ Xe-CF 4 (2, 5, 10, 50%) ▲ Xe-isobutene (2%) CF4 is cheap, easy to use, and does not absorb light (t 0 possible)

12. The new Micromegas-TPC for charge & light collection The new Micromegas-TPC for charge & light collection Woven wires http://www.bopp.ch/ Gap 250 μm Cathode Charge read out Light read out Primary ionization (t 0 )

13. Advantages of the new device measure the light emitted by ionization. measure the light emitted by ionization. the anti-correlation Charge-Light. the anti-correlation Charge-Light. Better identification of particles and good determination of the energy deposition localization. Better identification of particles and good determination of the energy deposition localization. A well sealed feedthrough

14. I0I0 I1I1

15. Research & development Continue..