# Presentation: 167695

- Dmitri Denisov
- Fermilab
*SLHC/VLHC Workshop*
*Fermilab, October 2003*
- Outline:
- Energy frontier
- Properties of interactions at 100TeV
- What we would like to measure?
- Accelerator/detector interface
- Detectors for 100TeV
- R&D plans

**Very Large Hadron Collider**

**VLHC Experiments: Overview**

## Tevatron is progressing with delivering world highest energy collisions of 2TeV to CDF and D0 experiments
“Top factory”
In a few years LHC will come on-line with 14TeV center of mass energy
“Higgs factory”
Progress in high energy physics has always been correlated with increase in energy of accelerators/colliders
Higher mass objects could be created
Smaller distances could be studied
Next “natural” step is ~100 TeV center of mass energy
How can we reach such energy?
Can we build detectors for such a machine?

- “Top factory”
- In a few years LHC will come on-line with 14TeV center of mass energy
- “Higgs factory”
- Progress in high energy physics has always been correlated with increase in energy of accelerators/colliders
- Higher mass objects could be created
- Smaller distances could be studied
- Next “natural” step is ~100 TeV center of mass energy
- How can we reach such energy?
- Can we build detectors for such a machine?

**Energy Frontier**

## There are plenty of documented studies available
Eloisatron studies book
Snowmass 1996 and 2001 reports
VLHC 2001 Design Study report
http://www.vlhc.org
LHC detectors design reports
SSC detectors design reports
 x2 in energy only...

Experience with running Tevatron and LHC detectors

- Eloisatron studies book
- Snowmass 1996 and 2001 reports
- VLHC 2001 Design Study report
- _[http://www.vlhc.org](http://www.vlhc.org/)_
- LHC detectors design reports
- SSC detectors design reports
-  x2 in energy only...
- Experience with running Tevatron and LHC detectors

**Available Literature**

## Most results are for 100TeV center of mass energy 

Increase in total and inelastic cross sections is small
Less then x2 in comparison with Tevatron
Less then ~30% in comparison with LHC

Values at 100TeV
Total  ~ 150mb
Inelastic  ~100mb

- Increase in total and inelastic cross sections is small
- Less then x2 in comparison with Tevatron
- Less then ~30% in comparison with LHC
- Values at 100TeV
- Total  ~ 150mb
- Inelastic  ~100mb

**Properties of (soft) pp Interactions **

## Number of charged particles produced in 100TeV collision is similar to Tevatron/LHC energies
Average number is ~102 particles per interaction
Most particles are concentrated in the central rapidity “platou” region

Important to remember
Distribution of number of particles per interaction is non-Gausian
there is long tail into high multiplicity region

- Average number is ~102 particles per interaction
- Most particles are concentrated in the central rapidity “platou” region
- Important to remember
- Distribution of number of particles per interaction is non-Gausian
- there is long tail into high multiplicity region

**Charged Particles Multiplicities**

## Most of the particles produced at 100TeV are soft
Average Pt of the particle is ~0.6GeV

This feature might be useful to reduce occupancies in the central region where most high mass objects will decay to
Clean soft charged tracks in the forward region using solenoidal field

We assume that soft processes simulation is valid from 2TeV to 100TeV jump
Cosmic rays cross section measurements confirm this assumption

- Average Pt of the particle is ~0.6GeV
- This feature might be useful to reduce occupancies in the central region where most high mass objects will decay to
- Clean soft charged tracks in the forward region using solenoidal field
- We *assume* that soft processes simulation is valid from 2TeV to 100TeV jump
- Cosmic rays cross section measurements confirm this assumption

**Particles P****t**** Distribution**

- Pythia

## Radiation Doses in Central Tracker

- Mostly affected areas are
- Central tracker
- Calorimetry in shower maximum
- Close to beam pipe elements- see N. Mokhov talk on Saturday
- As expected from total cross section and Pt spectrum radiation doses in the central region are practically independent of center of mass energy and linear function of luminosity
- For central tracker typical dose at 10cm radius at 1034cm-2sec-1 luminosity is ~5-10Mrad per year

**Radiation Doses in Central Tracker**

## 
Doses in the shower maximum are reasonable (~ 0.1Mrad/year) in the central region, but raise sharply in the forward region
All energy is going in the forward direction

Good eta coverage needed for many studies (missing Et determination) sets hard requirements on the forward calorimetry
~Grad/year

- Doses in the shower maximum are reasonable (~ 0.1Mrad/year) in the central region, but raise sharply in the forward region
- All energy is going in the forward direction
- Good eta coverage needed for many studies (missing Et determination) sets hard requirements on the forward calorimetry
- ~Grad/year

**Radiation Doses in Calorimetry**

## Because there is no specific physics process to be studied general purpose detector(s) is a must for an energy frontier machine
Two general detectors sounds like reasonable minimal approach
Verification of the results obtained in very complex experimental and analysis conditions
Competition
In order to optimize detector design usually set of benchmark processes are used
Top detection
W mass resolution
Higgs/SUSY discovery
Others which depends upon “hot topics” at the design stage
Final design is a compromise between different requirements
Larger tracking volume has advantages for tracking and B physics, but adds material between calorimeter and makes calorimeter less hermetic and more expensive 

- Two general detectors sounds like reasonable minimal approach
- Verification of the results obtained in very complex experimental and analysis conditions
- Competition
- In order to optimize detector design usually set of benchmark processes are used
- Top detection
- W mass resolution
- Higgs/SUSY discovery
- Others which depends upon “hot topics” at the design stage
- Final design is a compromise between different requirements
- Larger tracking volume has advantages for tracking and B physics, but adds material between calorimeter and makes calorimeter less hermetic and more expensive

**What We Would Like to Measure?**

## In order to discover top quark both CDF and D0 had to detect:
Leptons (e/)
Jets
Tag b-quarks (associated lepton, displaced vertex)
Neutrinos (missing Et)

We need 
tracker (e/, vertex)
calorimeter (jets, missing Et)
muon system

Basically we are measuring all stable (lifetime more ~ size of the detector) known particles

- Leptons (e/)
- Jets
- Tag b-quarks (associated lepton, displaced vertex)
- Neutrinos (missing Et)
- We need
- tracker (e/, vertex)
- calorimeter (jets, missing Et)
- muon system
- Basically we are measuring all stable (lifetime more ~ size of the detector) known particles

**What We Would Like to Measure - Continue**

## Interaction region sizes
Transverse plane
A few microns in diameter
As a point for precision tracking
For short lived particles detection
Longitudinal axis
Longer
Easier to separate multiple interactions 
Lower local occupancies and radiation doses
Shorter
smaller (cheaper) detectors
better missing Et resolution
From Snowmass and other studies number of ~ 10cm came as baseline number
 Reasonable from the accelerator stand point

- Transverse plane
- A few microns in diameter
- As a point for precision tracking
- For short lived particles detection
- Longitudinal axis
- Longer
- Easier to separate multiple interactions
- Lower local occupancies and radiation doses
- Shorter
- smaller (cheaper) detectors
- better missing Et resolution
- From Snowmass and other studies number of ~ 10cm came as baseline number
-  Reasonable from the accelerator stand point

**Major Accelerator/Detector Interface Parameters - 1**

## Bunch spacing time
Shorter bunch spacing reduce number of interactions per crossing
Events pileup reduction
Complicates detectors and electronics
Natural limit
(detector size)/c
~20ns (LHC’s choice)
DC beam?

Very important
Beam halo
Other accelerator induced “backgrounds”
Beam aborts
He from the tunnel

- Shorter bunch spacing reduce number of interactions per crossing
- Events pileup reduction
- Complicates detectors and electronics
- Natural limit
- (detector size)/c
- ~20ns (LHC’s choice)
- DC beam?
- Very important
- Beam halo
- Other accelerator induced “backgrounds”
- Beam aborts
- He from the tunnel

**Major Accelerator/Detector Interface Parameters - 2**

- “Simulation” of large
- multiplicity crossing...

## General purpose colliding detector design has been pretty stable over last 10-15 years
Tracking in the central solenoid field with precision vertexing
Hermetic electro-magnetic and hadron calorimetry with fine space segmentation and good rapidity coverage
Large acceptance muon system with good triggering and tracking capabilities

- Tracking in the central solenoid field with precision vertexing
- Hermetic electro-magnetic and hadron calorimetry with fine space segmentation and good rapidity coverage
- Large acceptance muon system with good triggering and tracking capabilities

**General Purpose Detector**

## In order to preserve tracker momentum resolution
p/p   ~

Increase detector lever arm (L) - cost
Increase magnetic field (B) – at the limit
Improve  coordinate accuracy  of detectors det  to a few micron level 

Major problem for a VLHC tracker is to keep momentum resolution at reasonable level for high pt tracks
Give up momentum measurement a’la Run I Tevatron D0 detector?

- p/p   ~
- Increase detector lever arm (L) - cost
- Increase magnetic field (B) – at the limit
- Improve  coordinate accuracy  of detectors det  to a few micron level
- Major problem for a VLHC tracker is to keep momentum resolution at reasonable level for high pt tracks
- Give up momentum measurement a’la Run I Tevatron D0 detector?

**Central Tracker**

## Shower depth is ~lnE
 Minor size increase in comparison with LHC 
Energy resolution:
	Electro-magnetic: ~15%/E,  0.5% at  1TeV 
   Hadron ~50%/E,  2% at 1TeV 
Calorimetry gets very precise at high energy!
Issue
 Events pile up
~50GeV/jet cone at L=1034 cm-2sec-1
Background energy fluctuates and luminosity dependent 

-  Minor size increase in comparison with LHC
- Energy resolution:
- 	Electro-magnetic: ~15%/E,  0.5% at  1TeV
-    Hadron ~50%/E,  2% at 1TeV
- Calorimetry gets very precise at high energy!
- Issue
-  Events pile up
- ~50GeV/jet cone at L=1034 cm-2sec-1
- Background energy fluctuates and luminosity dependent

**Calorimetry - 1**

## Main specifications for VLHC calorimetry
Radiation hard: ~5Mrad in the central region and ~10Grad in the forward region 
Small constant term, stable, easy to calibrate
Thick – missing Et, energy resolution
Fast – signal collection time below bunch spacing

Multiple options available
Scintillation based calorimetry
LAr
Crystals
High density gas calorimetry

Calorimetry looks OK for luminosity of 1034 cm-2 sec–1, but not many choices for 1035 cm-2 sec–1

- Radiation hard: ~5Mrad in the central region and ~10Grad in the forward region
- Small constant term, stable, easy to calibrate
- Thick – missing Et, energy resolution
- Fast – signal collection time below bunch spacing
- Multiple options available
- Scintillation based calorimetry
- LAr
- Crystals
- High density gas calorimetry
- Calorimetry looks OK for luminosity of 1034 cm-2 sec–1, but not many choices for 1035 cm-2 sec–1

**Calorimetry - 2**

## 
High energy muons are important for search of heavy objects and low energy muons for t, b quarks tagging 

Muon detectors are BIG!

Radiation damage is less of a problem for muon detectors
but doses especially from accelerator and neutrons have to be carefully estimated

High energy muons start to irradiate  (em showers) and loose more energy due to radiation losses then due to ionization at a few hundred GeV
Creates backgrounds in muon tracking detectors and requires corrections for momentum measurements 

*High* energy muons are important for search of heavy objects and *low* energy muons for t, b quarks tagging
- Muon detectors are BIG!
- Radiation damage is less of a problem for muon detectors
- but doses especially from accelerator and neutrons have to be carefully estimated
- High energy muons start to irradiate  (em showers) and loose more energy due to radiation losses then due to ionization at a few hundred GeV
- Creates backgrounds in muon tracking detectors and requires corrections for momentum measurements

**Detection of Muons - 1**

## 

Momentum resolution is limited by factors similar to the central tracker

p/p ~          

Design SDC (SSC) muon system resolution is ~ 10% at pt ~ 1TeV/c

Precision measurement of very high energy muons is a challenging task

- Momentum resolution is limited by factors similar to the central tracker
- p/p ~
- Design SDC (SSC) muon system resolution is ~ 10% at pt ~ 1TeV/c
- Precision measurement of very high energy muons is a challenging task

**Detection of Muons - 2**

## Radiation hard detectors
 Central tracking and calorimetry
Very high precision tracking to measure muon momentum in the range 1TeV to 10TeV with a few % resolution
 Field? Size? Accuracy?
Effect of events overlap on final states recognition 
Handling 5TeV per trigger tower from min_bias overlaps?
The only way to reduce number of events per crossing is smaller bunch spacing. Can we build detectors/electronics which will resolve collisions a few ns apart
Begining of one shower is in the em calorimeter while hadron calorimeter still sees remnants of the shower from previous collision?
Reduction in cost of the detectors, trigger and DAQ systems
Can design detectors with slightly worse parameters, but cheaper with less construction time?
For many years we did not see new principles of particle detection.
Need reasonable level of R&D for the new methods of particles detection, however strange they look from the first glance

-  Central tracking and calorimetry
- Very high precision tracking to measure muon momentum in the range 1TeV to 10TeV with a few % resolution
-  Field? Size? Accuracy?
- Effect of events overlap on final states recognition
- Handling 5TeV per trigger tower from min_bias overlaps?
- The only way to reduce number of events per crossing is smaller bunch spacing. Can we build detectors/electronics which will resolve collisions a few ns apart
- Begining of one shower is in the em calorimeter while hadron calorimeter still sees remnants of the shower from previous collision?
- Reduction in cost of the detectors, trigger and DAQ systems
- Can design detectors with slightly worse parameters, but cheaper with less construction time?
- For many years we did not see new principles of particle detection.
- Need reasonable level of R&D for the new methods of particles detection, however strange they look from the first glance

**Issues for Studies – VLHC Detectors **

## VLHC general purpose detector design will need
Tracking in magnetic field, hermetic calorimetry, and muon system
Radiation doses in the central rapidity region increase slowly with collider energy and linearly with luminosity
Detectors similar to SSC/LHC could be used to study 100TeV collisions at luminosity ~1034cm-2sec-1
Measuring momentum of high pt tracks is a challenge
Luminosities well above 1034cm-2sec-1 create serious experimental problems
Radiation load
Events pileup
Hadron collider is the only currently viable road to the energy frontier, 100 TeV VLHC will provide opportunity
To create new particles in the 10 TeV mass range
To “look” at distances of ~10-20cm

- Tracking in magnetic field, hermetic calorimetry, and muon system
- Radiation doses in the central rapidity region increase slowly with collider energy and linearly with luminosity
- Detectors similar to SSC/LHC could be used to study 100TeV collisions at luminosity ~1034cm-2sec-1
- Measuring momentum of high pt tracks is a challenge
- Luminosities well above 1034cm-2sec-1 create serious experimental problems
- Radiation load
- Events pileup
- Hadron collider is the only currently viable road to the energy frontier, 100 TeV VLHC will provide opportunity
- To create new particles in the 10 TeV mass range
- To “look” at distances of ~10-20cm

**VLHC Detectors Summary**