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MB studies at Very High Energy Hadron Collider. A jump into the Future !. VLHC the Very Large Hadron Collider. Concept: 2 stages project Stage 1: Build a BIG TUNNEL, fill with a “cheap” 40 TeV machine; Stage 2: Later upgrade it to 200 TeV ; Place: Fermilab (?)
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MB studies at Very High Energy Hadron Collider A jump into the Future !
VLHC the Very Large Hadron Collider
Concept:2 stages project • Stage 1: Build a BIG TUNNEL, fill with a “cheap” 40 TeV machine; • Stage 2: Later upgrade it to 200 TeV; • Place:Fermilab (?) • Take advantage of the space and excellent geology around Fermilab; • Use the avaiable facilities; • When:2020 (?) • TESLA (2013) • Cost (ECB): ~ 4130 M$ (3790 M$ for SSC Y2001$) 2009 US Expenses TESLA/LC 2013 2004 2020 VLHC
Michigan Lake Fermilab Tevatron
MB studies for Detector & Trigger use - Comparison of Pythia and Isajet (E4-WG3 Detectors) • Understand the particle/Energy flux, Multiplicity, PT, <PT>… • Which Rapidity Region we have to cover ? • How well MC Generators do ? (what is your opinion?) • … only then start to think about a VHM Trigger
Total Cross Section PYTHIA 6.129
Total Cross Section “No hard scattering at all; events consist only of beam jets. To represent the total cross section it’s better to use a sample of TWOJET events with lower limit on PT chosen to give a cross section equal to the inelastic cross section or to use a mixture of MINIMUM BIAS and TWOJET events” - ISAJET Manual ISAJET 7.51
Generated 20000 Minimum Bias events at 4 center of mass energies: s= 40,100,175,200 TeV; • Used both Isajet and Pythia Monte Carlo Program • no Detector Simulation (toy or other) taken into account; • considered only charged tracks; • mean PT of the event defined as: • <PT> evaluated considering different cuts on the minimum track PT; • Event particle density:
Rapidity Distributions Pythia 6.129 Arb. Units h
Rapidity Distribution Isajet 7.51 Arb. Units h
Rapidity – Pythia vs Isajet Arb. Units s=40 TeV h
Rapidity – Pythia vs Isajet Arb. Units s=100 TeV h
Rapidity – Pythia vs Isajet Arb. Units s=200 TeV h
PT Distribution of Charged Particles Pythia 6.129
Charged particles <PT> PT> 5.0 GeV/c any PT PT> 1.0 GeV/c Pythia 6.129
Energy Flow Energy Flow, 100 TeV, 1 Event 103 102 101 100 Energy [GeV] -10 -8 -6 -4 -2 0. 2. 4. 6. 8. 10. h Almost all the Energy is in the Forward Region of h
Average Number of Charged Tracks Pythia 6.129 VLHC 100 10 Charged Multiplicity .01 .1 1 10 100 1000 s [TeV] <Multiplicity> = 125 (@ 100 TeV)
Number of tracker “elements” • for 100-200 TeV of CME the expected number of tracks is: Ntrk ~ 50 x 100 = 5x10 3 (interactions per bunch crossing) • For reasonable reconstruction/triggering, occupancy below 1% is needed: NElem ~ 5 x 103 x 102 = 5x105 Elements/Layer • A number of Layer > 20 is needed: NElem ~ 5 x 105 x 2x10= 107 number of tracker “elements”
Number of tracker “elements” • special low luminosity runs are necessary to avoid multiple interactions; • in principle such a tracking system should be able to reach reasonable high values of Z. How trustable are these MC Simulations ?
How well PYTHIA do ? Simulated and Reconstructed inclusive distributions poorly match the Experimental Data (CDF MB @ 1.8 TeV); The shape of the <PT> vs multiplicity correlation is roughly reproduced, But <PT> values are considerably lower than the measured ones.
Conclusions • cross sections and multiplicities changing with energy increase very slowly; • Multiplicity distributions have long non-Gaussian tails; • Most of charged tracks are low momentum: <pT> ~ 0.6 GeV; • @ 100 TeV Pythia predict a mean charged track multiplicity of 125; • All the studied parameters and distributions are used to evaluate the behaviour of the Monte Carlo… we could see surprizes at very high energy.