Mark Thomson University of Cambridge  LoI loose ends  New physics studies?  What next... Future Plans… This talk:

TILC09, Tsukuba, 21/04/2009Mark Thomson2  LoI Debrief  Generally ILD physics/optimisation studies rather successful  However a few loose ends: Backgrounds:  A great deal of progress on understanding backgrounds…  Reconstruction software  Nevertheless, the TPC studies are very impressive  Silicon tracking studies made major progress, but (in my opinion) raised a number of questions Physics:  Still differences between analyses used by ILD and SiD which aren’t understood  In particular, Higgs BRs from qqcc  Some very nice studies, but what should we do with them ? In the next few slides, a few ideas to hopefully prompt discussion regarding future directions…  The LoI process, pushed ILD forwards very rapidly  Should try not to lose too much momentum…

TILC09, Tsukuba, 21/04/2009Mark Thomson3  Large fraction of hits from low energy electrons/positrons from photon conversions  Form tight helices, “micro-curlers”, along length of TPC  Background concentrated on relatively few TPC readout pads  Developed PatRec software to identify and remove “micro-curlers” 150 BXs of pair background TPC Background

TILC09, Tsukuba, 21/04/2009Mark Thomson4 Top (p T >1 GeV)Background Raw hits ~8,600 ~265,000 After ~8,500 ~3,000  Effective removal of large fraction of background hits  By eye – clear that this should be no problem for PatRec

TILC09, Tsukuba, 21/04/2009Mark Thomson5  Superimpose 150 BXs TPC background on  For 100 events, NO loss in track-finding efficiency observed  Similar story for 3x nominal background  Believe this is a clear demonstration of the robustness of a TPC operating in ILC beam conditions

TILC09, Tsukuba, 21/04/2009Mark Thomson6 Background: VTX  Background in VTX detector complicated by assumptions for Si pixel readout rate  IF one assumes single BX tagging capability then background is not an issue  For ILD studies “conservatively” assume 30  s / 125  s integration times for VTX layers (0,1) and (2,3,4,5) respectively  Therefore VTX integrates over 83/333 BXs  Superimpose on fully-hadronic top-pair events at 500 GeV 200,000 background hits per event !  Also consider finite cluster size of background hits (~10 pixels)  Significantly increases occupancy layer Occ % % % % % %

TILC09, Tsukuba, 21/04/2009Mark Thomson7 Background: VTX - fake tracks  Combinatorics produce fake “ghost” tracks  In addition to some real electron/positron background tracks  Large combinatoric background challenges pattern recognition  Reconfigured current algorithm (not ideal)  From 83/333 BXs overlayed on : reconstruct ~34 “ghost” tracks/event (~1/3 are genuine)  Rejected by requiring at least 1 SIT hit or >10 TPC associated hits 34/event 1/event Left with ~0.5 GeV per event (mixture of real tracks/combinatorics)

TILC09, Tsukuba, 21/04/2009Mark Thomson8 Personal view  TPC studies look pretty solid  The VTX studies assumed integration times of 83/333 BXs (31/125  s)  To get background level down to acceptable level assumed single BX-tagging capability in SIT and in TPC  Occupancies in inner layers are high for nominal ILC background i.e. 2-3 %  With assumed integration times, safety factor not great, i.e. for 10 x current background probably lose inner layers Issue of time-stamping in ILD needs more consideration Comments ? I believe:

TILC09, Tsukuba, 21/04/2009Mark Thomson9  Physics  Should think carefully about what to do with current physics studies  There are a number of individual publication being pursued (this is good)  But I would like to raise the possibility of a more general ILD physics publication addressing a couple of bigger issues..  How about a combined ILD physics paper ? e.g. comparing reach for different polarisations none 80% e - 80% e - ; 30 % e + 80% e - ; 60 % e + different luminosity spectra RDR low-p …  The text describing the analyses (at an appropriate level exists)  All results could be obtained by reweighting current samples  Such a publication would be timely; these are relevant questions for the design of the ILC Is this worth pursuing ?

TILC09, Tsukuba, 21/04/2009Mark Thomson10 Physics at 1 TeV  The question of ILD performance at 1 TeV is bound to come up  Should we be thinking about this now ?  What would this mean:  preparing stdHep files  simulation of some processes ? Comments ?

TILC09, Tsukuba, 21/04/2009Mark Thomson11  Optimisation Plans  To date concentrated on global optimisation  Now need to focus on more sub-detector specific issues  These fall into two categories: alternate technologies, e.g. DHCAL, Scint-W ECAL sub-detector “global” issues e.g. does the thickness of the TPC end-plate really matter ? … add your favourites here … Comments ?  We need to start to construct a list of questions we want to answer  Propose that each sub-detector group comes up with a list of such question (via EB reps)  We can then try and prioritise/make more concrete plans

TILC09, Tsukuba, 21/04/2009Mark Thomson12 That’s all