1 / 14

ILC-inspired TPC for Tlep ?

ILC-inspired TPC for Tlep ?. Philippe Schwemling. Machine relevant parameters. Circumference : 80 km Number of bunches : 4400 ( @ Z peak ) Bunch spacing : 18.2 m (55 ns). CLIC. ILC. Most demanding : lowest energies (Z peak )

piera
Télécharger la présentation

ILC-inspired TPC for Tlep ?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ILC-inspired TPC for Tlep ? Philippe Schwemling

  2. Machine relevant parameters • Circumference : 80 km • Number of bunches : 4400 (@ Z peak) • Bunchspacing : 18.2 m (55 ns)

  3. CLIC ILC Most demanding : lowestenergies (Z peak) Rates : 16.8 kHZhadronic Z decays (1 every 60 μs avg, or 1 every 1091 BC) 33,6 kHz Bhabhas (1 every 120 μs avg, or 1 every2182 BC)

  4. Whyconsider a TPC atTlep ? • Large (continuous) tracking volume atreasonableprice. • StrongpastexperiencewithTPCs (LEP) • Verylowmaterial budget (typically 0.05 X0 in r, up to 0.25 X0 includingendplates) • Continuoustrackingeases reconstruction of non-pointingtracks : • Physics signatures • PFA • dE/dx measurement (5% resolution)

  5. ILD TPC parameters • R internal : 229 mm • R out : 1808 mm • Z length : 2×2350 mm • Drift gas : Ar CF4(3%) isobutane (2%) • B=4 T • E = 350 V/cm (Arxiv 1006.3220v1) • Otherdata extractedfrom ILC TDR

  6. Gasproperties (Arxiv 1008.5068v2) Dt=50 μm/cm ≈800 μm (Comparable to ILD announced 2-hit r-ϕresol : 2 mm) W=80 μm/ns  drift time = 25μs (B=4 T, E=350 V/cm)

  7. Putting it all together • Average time betweenhadronicevents : 60 μs • Total drift time (electrons): 25 μs  on average, 0.4 hadroniceventdrifting in the TPC • Probability of eventsmixing in z negligible: 2-hit r-z resolutionis 8 mm, or 90 ns drift time, or 1.5 BC • A ILD inspired TPC withMicromegas position measurement looks viable as a TLep detector.

  8. Cooling and power pulsingconsiderations • ILC TPC end-plate power dissipation : 100 W/m2 (with power pulsing, i.e. 1% of the dissipation at 100% duty cycle) • TLep TPC endplate : 2700 W/m2 (not 10 KW/m2, power pulsing gains factor 27 only) • Most of the power comesfrom the back-end, whereprogresscanbeexpected R&D • FE is 5 mW/channel for 10 mm2/channel (500 W/m2 without power pulsing) • However, power pulsingis a source of complication, especiallycommon mode noise.

  9. Is power pulsing possible ? • There willbe a (not power pulsed) Si trackerinside the TPC • There willalsobe a fast (compared to the TPC) calorimeter. If it has to be power pulsed, canalso complementitwith a small non power-pulsed 4 π trigger layer (Si ? Scintillatingfiber ?) • Si tracker and calorimetercanbeused to trigger the TPC readoutelectronics power. • There is a lot of latency to build the trigger decision (60 μs on average) !

  10. Power pulsing in practice HARDROC chip performance studies 2 μs wouldallow a significant power saving. 25 μs isrelativelyuseless, but is the DAC isabsolutelyneeded ? (used to program the internal trigger threshold)

  11. Evaluation of the duty cycle Picture Takenfrom WenxingWang’sthesis Electronics live time : o (1 μs )+ 2 μs duty cycle canbe about 5-10% (on average) TPC endplate power consumptionwouldimmediately go down to 1000 W/m2

  12. Distorsions due to ions Ion drift time is about 1s  ions from 16 800 successive collisions presentatany time in drift volume May bemanageddifferentlyatTlepthanat ILC : gatingsecondary ions easieratTlep because no need for continuousoperation !

  13. Ion back-flow (cont’d) • Primary ions willbe a problem : • Primaryionization due to about 17 k eventspresentat the same time in the TPC • Calculationsexist for ILC, to betransposed to Tlep. • Track distorsion can in principlebecorrectedsince charge distribution isknown • How wellcanthiswork ?  Simulations • Note : ILC momentumresolution performance needdominated by hZ reconstruction. • Is such performance needed for physicsat the Z pole ?

  14. Conclusions • Effect of primary ions • To bequantified • If needed, performance of corrections to bestudied • Some R&D needed to minimize power consumption • Detector performance needed for Z-pole physicsmayberevisited. • Strongexisting detector expertise on TPCsat Saclay (and elsewhere) • A TPC for TLepis an attractive option !

More Related