# Presentation: 305853

## Physics reach vs luminosity goal & installation time for the LHC Luminosity Upgrade A first look

_**Physics reach**_** vs **_**luminosity goal**_** & **_**installation time**_** for the *****LHC Luminosity Upgrade*** _**A first look**_

*J.-P. Koutchouk , CERN/AT/MCS*
*Thanks to L. Rossi*

- CPT and LHC upgrade

## 1- Introduction 

**1- Introduction **

-  **    ****Factors that govern the **_**integrated luminosity**_** are:**
**The time it takes to reach nominal peak luminosity**,
**The effective collision time (turn-around, faults, unavailabilities: injectors, electricity..., machine studies**,
**The details of the luminosity decay during a run.**
- “Theoretical” calculations of any of the parameters governing these three aspects (except perhaps 3) have to be taken with much caution.
- The CPT “theorem” (better “fit”) is a pragmatic approach requiring a “_**complexity**_” to be evaluated. For control room people, this says a lot: the complexity of a storage rings is a control room concept.

- CPT and LHC upgrade

## 2.- The Model for the LHC luminosity increase 

**2.- The Model for the LHC luminosity increase **

**Adaptative complexity**
- Found in the range 0.9 -> 4.3 for p-colliders with an average of 2.4.
- We shall use a strategy of varying complexity depending on the closeness of the luminosity to the estimated luminosity goal:
*Constant factor + linear and quadratic dependences on closeness → c****{0.5, 3.5}*
**asymptotic increase above luminosity goal**
- Starting at 5% per year and saturating at 20%.

- CPT and LHC upgrade

## 2.- The Model for the LHC integrated luminosity

**2.- The Model for the LHC integrated luminosity**

**Exponential decay during run**
- Including beam-beam, IBS and rest-gas
**Optimal run duration for a 70 minutes turn-around time**
**Time planned for physics: 10****7**** seconds**
**Machine availability for physics: 80%**
**Running till 2022.**

- CPT and LHC upgrade

## Complexity in the case of no upgrade

***Complexity in the case of no upgrade***

- CPT and LHC upgrade

## Luminosity profile in the case of no upgrade

***Luminosity profile in the case of no upgrade***

- CPT and LHC upgrade

## Improvement in 1/√N in the case of no upgrade

***Improvement in 1/******√N****** in the case of no upgrade***

- CPT and LHC upgrade

## Complexity in the case of the “reference” upgrade

- CPT and LHC upgrade

## Luminosity profile in the case of the “reference” upgrade

***Luminosity profile in the case of the “reference” upgrade***

- CPT and LHC upgrade

## Improvement in 1/√N in the case of the “reference” upgrade 

- CPT and LHC upgrade

## Physics reach versus Luminosity goal

**and year of upgrade**

_***Assumptions:***_
*** *****Same upgraded beam current: kb×2, Nb=1.7 **
** ****Same strategy for the complexity**
** ****Same stop for one year to upgrade the detectors**
**Vary the year of upgrade and luminosity goal**

- CPT and LHC upgrade

## Slide 12

- CPT and LHC upgrade

## Conclusions 

**Conclusions **

- Working on the “complexity” appears _less arbitrary_ than working directly on luminosity profiles.
- LHC should reach the nominal luminosity in 2012 in a “reasonably” optimistic scenario.
- From 2014, the improvement in statistics becomes modest.
- In the reference scenario where the luminosity upgrade  was essentially due to the increased beam current, _5 years_ are needed to reach the luminosity goal!
**      **

- CPT and LHC upgrade

## Conclusions 

**Conclusions **

- The _×10_ increase in peak L yields about a _factor of two_ of improvement of the statistics (precision physics) in this same scenario.
- The yield of a significantly smaller luminosity goal appears then marginal (even if the one year shutdown is suppressed).
- The largest potential of improvement is likely to be in a _**minimization of complexity increase**_ related to the upgrade: _*this favors very much stronger focusing with a new Xing angle & LR compensation strategy and no or small increase of beam current.*_
- Cooking: scenarios and calculations to quantify the above.
**      **

- CPT and LHC upgrade