4 th international workshop on vhmp, alushta 2 june 2003 carmine elvezio pagliarone a j u m p i n t...

44thth International Workshop on VHMP, International Workshop on VHMP, Alushta 2 June 2003Alushta 2 June 2003 Carmine Carmine Elvezio PagliaroneElvezio Pagliarone

A jump into the

A jump into the

Future !Future !


VLHCVLHCthe Very Large Hadron the Very Large Hadron

ColliderCollider


Concept:Concept: 2 stages project2 stages project

Stage 1: Stage 1: Build a BIG TUNNEL, fill with a “cheap” Build a BIG TUNNEL, fill with a “cheap” 40 40 TeVTeV machine; machine; Stage 2: Stage 2: Later upgrade it to Later upgrade it to 200 TeV200 TeV;;

Place:Place: Fermilab (?)Fermilab (?)

Take advantage of the space and excellent Take advantage of the space and excellent geology geology around Fermilab;around Fermilab; Use the avaiable facilities;Use the avaiable facilities;

When:When: 2020 (?)2020 (?)

TESLA (2013)TESLA (2013)

Cost (ECB): Cost (ECB): ~ 4130 M$ ~ 4130 M$ (3790 M$ for SSC Y2001$)(3790 M$ for SSC Y2001$)

2004

2004

2009

2009

2013

2013

VLHCVLHC

TESLA/LCTESLA/LC

2020

2020

US US ExpensesExpenses


200200


FermilabFermilab

MichiganMichiganLakeLake

TevatronTevatron


why Fermilab ?


MB studies for Detector & Trigger use - Comparison of

Pythia and Isajet(E4-WG3 Detectors)

- Understand the particle/Energy flux, Multiplicity, PUnderstand the particle/Energy flux, Multiplicity, PTT, , <P<PTT>…>…- Which Rapidity Region we have to cover ?Which Rapidity Region we have to cover ?- How well MC Generators do ? (what is your How well MC Generators do ? (what is your opinion?)opinion?)- … … only then start to think about a VHM Triggeronly then start to think about a VHM Trigger


Total Cross Section

Physical Process s=40 TeVs=100

TeVs=175

TeVs=200

TeV

Elastic Cross Section - - - -

Single DiffractiveSingle Diffractive 7.60 mb7.60 mb 7.96 mb7.96 mb 8.17 mb8.17 mb 8.22 mb8.22 mb

Double DiffractiveDouble Diffractive 11.38 mb11.38 mb 12.83 mb12.83 mb 13.73 mb13.73 mb 13.95 mb13.95 mb

Low PLow PTT Processes Processes -- -- -- --

Inelastic Cross SectionInelastic Cross Section 93.07 mb93.07 mb 107.1 mb107.1 mb 116.7 mb116.7 mb 119.2 mb119.2 mb

Total Cross Section - - - -

PYTHIA 6.129


Total Cross Section

Physical Process s=40 TeVs=100

TeVs=175

TeVs=200

TeV

Elastic Cross Section - - - -

Single Diffractive - - - -

Low PT Processes - - - -

Inelastic Cross Section

137 mb 157 mb - 174 mb

Total Cross Section - - - -

ISAJET 7.51

“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


hep-ph 0011157


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:

N

j

jTT P

NP

1

1

N


Rapidity Distributions

Pythia 6.129

A

rb.

Un

its

Arb

. U

nit

s


Isajet 7.51

Rapidity Distribution

A

rb.

Un

its

Arb

. U

nit

s


Rapidity – Pythia vs Isajet

s=40 TeV

A

rb.

Un

its

Arb

. U

nit

s



s=100 TeV

A

rb.

Un

its

Arb

. U

nit

s



s=200 TeV

A

rb.

Un

its

Arb

. U

nit

s


PPTT Distribution of Charged Particles Distribution of Charged Particles

CMECME <<PPTT>>s= 40s= 40 TeVTeV 0.45 GeV/c0.45 GeV/c

s= 100s= 100 TeVTeV 0.49 GeV/c0.49 GeV/c

s= 200s= 200 TeVTeV 0.53 GeV/c0.53 GeV/c

Pythia 6.129


Charged particles <PT>

PT> 1.0 GeV/c

PPTT> 5.0 > 5.0 GeV/cGeV/c

Pythia 6.129

any PT


Energy Flow

101033

101022

101011

101000

-10 -8 -6 -4 -2 0. 2. 4. 6. 8. 10.-10 -8 -6 -4 -2 0. 2. 4. 6. 8. 10.

En

erg

y [

GeV

]En

erg

y [

GeV

]

Almost all the Energy is in the Forward Region of Almost all the Energy is in the Forward Region of

Energy Flow, 100 TeV, 1 Energy Flow, 100 TeV, 1 EventEvent


Average Number of Charged Tracks

100100

1010.01 .1 1 10 100 1000.01 .1 1 10 100 1000

s [TeV]s [TeV]

Ch

arg

ed

C

harg

ed

M

ult

iplicit

yM

ult

iplicit

yPythia 6.129

VLHCVLHC

<Multiplicity> = 125 <Multiplicity> = 125 (@ 100 (@ 100 TeV)TeV)


Number of tracker “elements”Number of tracker “elements”

for 100-200 TeV of CME the expected number of tracks for 100-200 TeV of CME the expected number of tracks is:is:

NNtrktrk ~ 50 x 100 = 5x10 ~ 50 x 100 = 5x10 33

(interactions per bunch crossing)(interactions per bunch crossing)

For reasonable reconstruction/triggering, occupancy For reasonable reconstruction/triggering, occupancy below 1%below 1% is needed:is needed:

NNElemElem ~ 5 x 10 ~ 5 x 1033 x 10 x 102 2 = 5x10= 5x105 5 Elements/LayerElements/Layer

A number of Layer > 20 is needed:A number of Layer > 20 is needed:

NNElemElem ~ 5 x 10 ~ 5 x 1055 x 2x10 x 2x10 = 10= 107 7 number of tracker “elements”number of tracker “elements”


Number of tracker “elements”Number of tracker “elements”

special low luminosity runs are necessary to avoid special low luminosity runs are necessary to avoid multiple multiple interactions;interactions;

in principle such a tracking system should be able to in principle such a tracking system should be able to reach reach reasonable high values of Z.reasonable high values of Z.

How trustable are these MC Simulations ?How trustable are these MC Simulations ?


Mean transverse momentum vs multiplicity

CDF CDF DataData


Mean Transverse momentum vs multiplicity (MC)


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.

How well PYTHIA do ?How well PYTHIA do ?


Conclusions

cross sections and multiplicities changing with energy cross sections and multiplicities changing with energy increaseincrease very slowly;very slowly;

Multiplicity distributions have long non-Gaussian tails;Multiplicity distributions have long non-Gaussian tails;

Most of charged tracks are low momentum: Most of charged tracks are low momentum: <p<pTT> ~ 0.6 > ~ 0.6 GeVGeV;;

@ 100 TeV Pythia @ 100 TeV Pythia predictpredict a mean charged track a mean charged track multiplicity multiplicity

of of 125125;;

All the studied parameters and distributions are used to All the studied parameters and distributions are used to

evaluate the behaviour of the Monte Carlo… we could evaluate the behaviour of the Monte Carlo… we could seesee

surprizes at very high energy.surprizes at very high energy.

4 th international workshop on vhmp, alushta 2 june 2003 carmine elvezio pagliarone a j u m p i n t...

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