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US-LHC Activities in AD. Tanaji Sen. Overview. The LHC US-LHC Construction Project US-LARP Goals and Activities Accelerator Physics Instrumentation Beam Commissioning [email protected] The wise speak only of what they know Gandalf, Lord of the Rings.

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Overview
Overview

  • The LHC

  • US-LHC Construction Project

  • US-LARP Goals and Activities

  • Accelerator Physics

  • Instrumentation

  • Beam Commissioning

  • [email protected]

The wise speak only of what they know

Gandalf, Lord of the Rings


LHC

Control Room



Us lhc construction project
US-LHC Construction Project

  • Interaction Region Quads (FNAL)

  • Interaction Region Dipoles (BNL)

  • Interaction Region Cryogenic Feedboxes (LBL)

  • Interaction Region Absorbers (LBL)

  • Accelerator Physics (FNAL, BNL, LBL)

    - related to IR designs and magnets

    - ecloud, noise effects

Last magnets to be delivered in 2006


Lhc ir quads at fnal

MBXA

CORR

MQXA

CORR

MQXB

CORR

MQXB

CORR

MQXA

DFBX

TAS

“D1”

“Q3”

“Q2”

“Q1”

FNAL

BNL

LBNL

CERN

KEK

LHC IR Quads at FNAL

FNAL quads

To IP

1st IR quad ready for

shipment in May 2004

  • FNAL is delivering 18

  • IR quads to the LHC

  • All IR quads

    (FNAL, KEK) are cryostatted at FNAL

  • and shipped from here

  • Last quad to be

    shipped in late 2006.


Fnal quads installed in ir8
FNAL quads installed in IR8

Mission Accomplished ?

Courtesy: J. Kerby


Us larp
US- LARP

Goals – stated by J. Strait (2002)

  • Extend and improve the performance of the LHC so as to maximize its scientific output in support of US-CMS and US-ATLAS

  • Maintain and develop the US labs capabilities so that the US can be the leader in the next generation of hadron colliders.

  • Serve as a vehicle for US accelerator physicists to pursue their research

  • Train future generations of accelerator physicists.

  • It is the next step in international cooperation on large accelerators.

    Fermilab has been appointed the “Host Laboratory” to lead this program.


Us larp institutions
US LARP Institutions

Two main areas:

  • High field magnets

  • Accelerator systems

    Accelerator Physics, Instrumentation, Collimation, Commissioning (beam & hardware)

  • High field magnets: BNL, FNAL, LBL

  • Accelerator Physics: BNL, FNAL, LBL

  • Instrumentation: BNL, FNAL, LBL, UT Austin

  • Collimation: SLAC

  • Commissioning: BNL, FNAL, LBL


Us larp goals
US-LARP Goals

  • Accelerator Physics and Experiments

    - understand performance limitations of current IRs and develop new designs

    - Beam dynamics calculations and related experiments

  • Develop high performance magnets for new higher luminosity IRs

    - large-aperture, high gradient quadrupoles using Nb3Sn

    - high field beam separation dipoles and strong correctors

  • Develop advanced beam diagnostics and instrumentation

    - luminosity monitor, tune feedback, Schottky monitor, rotatable collimators

    - other systems as needed for improving LHC performance

  • Commissioning

    - participate in the sector test and LHC beam commissioning

    - commission hardware delivered by the US



Luminosity and ir upgrade
Luminosity and IR upgrade

J. Strait

  • An IR upgrade is a straightforward way to increase the luminosity – by a factor of 2-3

  • It must also deal with higher beam currents and 10 times larger debris power at L=1035cm-2s-1

  • Several optics design issues

  • ~50% of LARP effort is in IR magnet design

A luminosity upgrade will be required

around ~2015 to keep the LHC physics

program productive.


Quadrupoles 1 st option
Quadrupoles 1st option

Advantages

  • Allows smaller β*, minimizes aberrations.

  • Lower accumulation of charged particle debris from the IP.

  • Operational experience from the first years of running.

    Disadvantages

  • More parasitic beam-beam interactions.

  • Crossing angle has to increase as 1/√β*

  • IR correction systems act on both beams simultaneously

Baseline Design


Dipoles 1 st 2 options
Dipoles 1st – 2 options

Advantages

  • Fewer parasitic interactions.

  • Correction systems act on single beams.

  • No feed-down effects in the quads

    Disadvantages

  • Large energy deposition in the

    dipoles.

  • Beta functions are larger →

    increases aberrations.

  • Longer R&D time for dipoles

  • Longer commissioning time

    after the upgrade.

Triplets

Doublets


Optics solutions
Optics Solutions

βMax = 9 km

Quads first

LARP magnet program aims to build 15T pole tip fields

βMax = 27 km

βMax = 25 km

Dipoles first: triplets

Dipoles first: doublets

J. Johnstone, TS


Ir design issues luminosity reach
IR Design Issues→ Luminosity Reach

  • Requirements on magnet fields and apertures

  • Optically matched designs at all stages

  • Energy deposition

  • Beam-beam interactions

  • Chromaticity and non-linear correctors, field quality

  • Dispersion correction

  • Susceptibility to noise, misalignment, ground motion; emittance growth

  • Closest approach of magnets to the IP (L*)

  • Impact of Nb3Sn magnets, e.g flux jumps

  • R&D time required to develop the most critical hardware and to integrate it in the LHC

  • ….. All need to be considered in defining the luminosity reach


Towards a reference baseline design
Towards a Reference Baseline Design

Proposal by F. Ruggiero (CERN)

  • “Define a Baseline, i.e. a forward looking configuration which we are reasonably confident can achieve the required LHC luminosity performance and can be used to give an accurate cost estimate by mid-end 2006 in a Reference Design Report

  • Identify Alternative Configurations

  • Identify R&D to

    - support the baseline

    - develop the alternatives”

Separately, the LARP magnet program has been tasked to

deliver a working prototype of a Nb3Sn quadrupole by 2009.



Long range interactions
Long-range interactions

  • Long-range beam-beam interactions are expected to affect LHC performance – based on Tevatron observations and LHC simulations

  • Wire compensator is proposed to mitigate their impact

  • RHIC has a 2 ring layout like the LHC – can be used to test the principle

Difference in kicks between a round beam and a wire < 1% beyond 3 sigma


Wire compensation in rhic and lhc
Wire compensation in RHIC and LHC

LHC

RHIC

IP

IP6

Reservedfor wire compensators

Location of wire compensators

Installation in Summer 2006

To be installed if required to improve

performance.

Feasibility would determine upgrade path


Rhic beam beam experiments
RHIC beam-beam experiments

  • Motivation for experiments: Test of wire compensation in 2007

    Determine if a single parasitic causes beam losses that need to be compensated

    Experiments in 2005 and 2006

    Remote participation at FNAL via logbook

  • Motivation for simulations: Tests and improvements of codes, predictions of observations in 2006 and of wire compensation

    Several groups: FNAL, SLAC, LBL, University of Kansas

    (coordinated at FNAL)

    Website: http://www-ap.fnal.gov/~tsen/RHIC


Beam beam experiments and simulations 2006
Beam-beam Experiments and Simulations (2006)

Simulated lifetimes show a linear dependence on the beam separation

FNAL Simulations

  • Beam lifetime responds to vertical separation but vertical separation  4σ (1st study – April 5th, 2006)

  • 4 studies in all (April-May) to explore larger separations and tune space

  • Analysis to find dependence on beam separation in progress

V. Ranjbar, TS


Wire compensator in rhic
Wire Compensator in RHIC

  • 1 unit in each ring

  • 2.5m long

  • Currents between 3.8 – 50 A

  • Vertically movable over 65mm

  • Install in Summer 2006


Pulsed wires
Pulsed Wires

  • Required for bunch to bunch compensation – PACMAN bunches

  • Challenges are the high pulse rate and turn to turn stability tolerances

LHC bunch pattern

Pulse pattern

Open Design Challenge



Energy deposition1
Energy deposition

  • Primary source of radiation in the IR magnets: pp collisions, ~ Luminosity

    Tevatron: debris power ~ 2 W

    LHC at 1035cm-2s-1, debris power ~ 9kW

  • Energy deposition is viewed as the major constraint on the IR upgrade

    Could be key in deciding between quads first or dipoles first.

  • Other sources include operational beam losses (e.g. beam gas scattering) and accidental losses (e.g. misfiring of abort kickers)


Energy deposition issues constraints
Energy Deposition Issues & Constraints

  • Quench stability→ Peak power density

    Require Epeak to be below the quench limit by a factor of 3

  • Magnet lifetime → peak radiation dose and lifetime limits for various materials

    Baseline LHC: expect lifetime ~ 7 years for IR magnets

    Upgrade LHC: requires new radiation hard materials

  • Dynamic heat loads → Power dissipation and cryogenic implications

    Require heat load < 10 W/m

  • Residual dose rates → hands on maintenance

    Require residual dose rates < 0.1 mSv/hr

  • Dedicated system of charged particle and neutral absorbers in the IRs


Energy deposition open mid plane dipole
Energy Deposition: Open Mid-plane Dipole

  • ED issues constrain the dipole design to have no coils in the mid-plane

  • Εpeakin SC coils ~0.4mW/g, below the quench limit

  • Estimated lifetime based on displacements per atom is ~10 years

  • Dipole design will require significant R&D, further LARP design work postponed

R. Gupta (BNL)

N. Mokhov


Quadrupole first design
Quadrupole first design

  • Without mitigation, Epeak > 4 mW/g. Target value is ~1.7mW/g

  • Mitigation by thick inner liner

  • Stainless steel liners are not adequate

  • Thick Tungsten-Rhenium liner reduces

    Epeak ~ 1.2 mW/g

I. Rakhno


Tertiary collimators
Tertiary Collimators

  • Designed to protect the detector and IR components from operational and accidental beam losses

Similar collimator used at A48

in the Tevatron to protect

against abort kicker misfire

For the LHC propose 1m long

Tungsten or Copper collimator

upstream of neutral absorber

To IP

N. Mokhov



Lhc injector in the lhc tunnel
LHC Injector in the LHC tunnel

  • Injector will accelerate beams from 0.45TeV to ~1.5TeV

    - Field quality of LHC better at 1.5GeV

    - Space charge effects lower, may allow

    higher intensity bunches

    - Could allow easier transition to LHC doubler

  • The injector will be installed in the LHC tunnel during scheduled LHC shutdowns

  • Return to the standard SPS injection into the LHC will be possible

  • The main magnets will be the type of super-ferric combined function magnets proposed for the VLHC I.

H. Piekarz (TD)


Lhc injector ler
LHC Injector (LER)

Vertical distance between LER and LHC

beams is 1.35m

VLHC low-field magnet

0.6 T (injection) → 1.6 T


Beam transfer
Beam Transfer

Fast pulsing magnets (PM) have to be turned off within 3 micro-secs after LHC is filled.

CERN Workshop October 2006

Sequence: SPS-> Injector -> LHC

--- what is not surrounded by

uncertainty cannot be the truth

R.P. Feynman


Instrumentation
Instrumentation

  • Schottky Monitor

  • Tune and Chromaticity Feedback

  • New Initiatives


Schottky monitor at the tevatron
Schottky Monitor at the Tevatron

Allows measurements of:

  • Tunes from peak positions

  • Momentum spread from average width

  • Beam-beam tune spread of pbars

  • Chromaticity from differential width

  • Emittance from average band power


Schottky monitor design
Schottky Monitor Design

Schottky Monitor will provide unique capabilities

  • Only tune measurement during the store

  • Bunch-by-bunch measurement of parameters such as Tune, Chromaticity

  • Average measurements as well

  • Momentum spread & emittance

  • Non invasive Technique

  • Diagnosis of beam-beam effects and electron cloud

  • R. Pasquinelli, A. Jansson

    4 Monitors to be installed in the LHC, Summer 2006


    Tune and chromaticity feedback
    Tune and Chromaticity feedback

    Goals

    • Control the tune during the acceleration ramp to avoid beam loss

    • Control the chromaticity during the snapback at start of ramp

    • PLL method: excite the beam close to the tune and observe the resonant beam transfer function

    • Then used in a feedback system to regulate the quadrupole current and tune

    Measurement in RHIC with tune

    feedback – tune changes ~ 0.001


    Tune chromaticity at the tevatron
    Tune & chromaticity at the Tevatron

    Phase Modulation Off

    • The Direct Diode Detection method (3D BBQ) from CERN implemented in the Tevatron – complements tune measurements from the Schottky monitors. More sensitive than the Schottky.

    • This 3D BBQ has been used to measure the chromaticity with a method due to D. McGinnis.

    • Interest in implementing this method at RHIC and the SPS

    Phase Modulation On

    C.Y. Tan


    New fnal initiatives proposed
    New FNAL Initiatives - proposed

    • AC Dipole (A. Jansson)

    • Electron lens compensation of head-on interactions (V. Shiltsev)

    • Crystal collimation (N. Mokhov)

    • Measure field fluctuations in magnets (V. Shiltsev)


    Commissioning
    Commissioning


    Lhc commissioning plan
    LHC Commissioning Plan

    Stage I

    II

    III

    IV

    No beam

    Beam

    Beam

    • I. Pilot physics run

      • First collisions

      • 43 bunches, no crossing angle, no squeeze, moderate intensities

      • Push performance (156 bunches, partial squeeze in 1 and 5, push intensity)

      • Performance limit 1032 cm-2 s-1 (event pileup)

    • II. 75ns operation

      • Establish multi-bunch operation, moderate intensities

      • Relaxed machine parameters (squeeze and crossing angle)

      • Push squeeze and crossing angle

      • Performance limit 1033 cm-2 s-1 (event pileup)

    • III. 25ns operation I

      • Nominal crossing angle

      • Push squeeze

      • Increase intensity to 50% nominal Performance limit 2 1033 cm-2 s-1

    • IV. 25ns operation II

      • Push towards nominal performance

    • R. Bailey (CERN)


    Expression of interest form
    Expression of Interest Form

    In anticipation of LHC-related studies using the SPS in the coming months and commissioning next year, LARP is soliciting interest for involvement in same.

    http://larp.fnal.gov/commissioningForm.html

    is the link for you to register your interest in being part of this effort.

    Please respond to Elvin Harms by June 1st


    Sps studies test lhc issues
    SPS studies – test LHC issues

    • LHCcollimatortests

    • LSS6 commissioning

    • TI8 extraction test

    • LSS4/LSS6 interleaved

    • LHC beam lifetime

    • LHC orbit feedback

    • BBLR – beam-beam compensation

    • LHC BLM tests in the PSB

      --- sample of studies planned

      From G. Arduini (CERN)


    Larp plans for beam commissioning
    LARP plans for Beam Commissioning

    • Refining areas of involvement, identifying CERN counterparts

      ~15 people signed up (across all 4 labs)

    • LARP presence during SPS run in Summer ’06

      3 FNAL people participating, room for a few more

    • Sector test presence planned

      About 2 weeks, late 2006 – early 2007

    • Software effort

      In support of instruments and control room here

    • Planning for long-term visits during LHC commissioning

    E. Harms


    What is lhc@fnal
    What is [email protected]?

    • A Place

      • That provides access to information in a manner that is similar to what is available in control rooms at CERN

      • Where members of the LHC community can participate remotely in CMS and LHC activities

    • A Communications Conduit

      • Between CERN and members of the LHC community located in North America

      • LARP use: Training before visiting CERN, Participating in Machine Studies, Analysis of performance, “Service after the Sale” of US deliverables

    • An Outreach tool

      • Visitors will be able to see current LHC activities

      • Visitors will be able to see how future international projects in particle physics can benefit from active participation in projects at remote locations.

        Planned Opening in September 2006

    E. Gottschalk


    Lhc@fnal
    [email protected]

    You can observe a lot just by

    watching

    Yogi Berra


    Control room at cern
    Control Room at CERN

    13 operators on shift + experts

    Started operation on Feb 1, 2006


    Lhc challenges
    LHC Challenges

    • Machine protection

    • Quench protection e.g at 7 TeV, fast losses < 0.0005% bunch intensity

    • Collimation (400 degrees of freedom!)

    • Controlling 2808 bunches

    • Snapback and ramp

      ΔQ’ (snapback) ~ 90,

      ΔQ’ (ramp & squeeze) ~ 320

    • -----


    Summary of larp activities
    Summary of LARP activities

    • Optics design of IR upgrade

    • Energy deposition calculations in IR magnets

    • Design of tertiary collimators

    • Beam-beam and wire compensation experiments

    • Optics design of a proposed LHC injector

    • Design of Schottky Monitor

    • Tests of tune and chromaticity tracking

    • Proposed new initiatives: AC dipole, E-lens, Crystal collimation, Field fluctuations

    • Participation in SPS and LHC sector tests

    • LHC beam commissioning

    • [email protected]


    Web pages
    Web pages

    • AD: larp.fnal.gov

    • US-LARP: dms.uslarp.org

    • LARP document database

      larpdocs.fnal.gov

    • FNAL-TD, BNL, LBL, SLAC also have web pages – links from the uslarp page

    E. McCrory


    Credits
    Credits

    • Accelerator Physics: J. Johnstone, N. Mokhov, I. Rakhno, V. Ranjbar

    • Instrumentation: A. Jansson, R. Pasquinelli, V. Shiltsev, C.Y. Tan

    • Commissioning: E. Harms, E. McCrory, J. Slaughter, M. Syphers



    Us larp activities in 2006
    US-LARP activities in 2006

    • Accelerator Physics

      FNAL: IR design, Beam-beam compensation, Energy deposition, tertiary collimators

      BNL: Beam-beam compensation

      LBL: Electron cloud

    • Instrumentation

      FNAL: Schottky monitor, tune feedback

      BNL: Tune feedback

      LBL: Luminosity monitor

    • Rotating collimators – SLAC

    • Magnets

      High field quads: FNAL, BNL, LBL

    • Commissioning – all labs


    Features of doublet optics
    Features of Doublet Optics

    • Symmetric about IP from Q1 to Q3, anti-symmetric from Q4 onwards

    • Q1, Q2 are identical quads, Q1T is a trim quad (125 T/m). L(Q1) = L(Q2) = 6.6 m

    • Q3 to Q6 are at positions different from baseline optics

    • All gradients under 205 T/m

    • At collision, β*x= 0.462m, β*y = 0.135m, β*eff= 0.25m

    • Same separation in units of beam size with a smaller crossing angle ΦE = √(β*R/ β*E) ΦR = 0.74 ΦR

    • Luminosity gain compared to round beams

    Including the hourglass factor,


    Lhc commissioning plan1
    LHC Commissioning Plan

    From R. Bailey (CERN)

    • Where are we ?

    • Overall strategy OK

      • Stage I 43 bunches

      • Stage II 75ns

      • Stage III 25ns low I

      • Stage IV 25ns high I

    • Stage I looked at

    • Some details behind

    • Need to make this into a detailed commissioning plan

      • Best developed by the people who will

      • implementit

        • Machine coordinators/Commissioners/EICs + Accelerator Systems

      • Work through 2006 (suggest 20% activity)


    Machine protection
    Machine protection

    • Metal damage

      450 GeV: 50 nominal bunches

      7 TeV: 7 x 109, about 6% of 1 bunch

    • Quench protection

      Fast losses 450 GeV: 109, 7TeV: 5x105

      During abort 450GeV: 1.4x109 p/m in gap

      7TeV: 2x106 p/m in gap

    • Collimator damage

      Fast losses 450 GeV: 260 bunches

      7 TeV: 4 bunches


    Lhc sector test with beam
    LHC Sector test with beam

    3.3 km of the LHC including one experiment insertion and a full arc



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