# Presentation: 091382

- LHC Accelerator Research Program
- Beam Instrumentation and Diagnostics
- DOE High Energy Physics Review
- LBNL
- 16-18 February, 2004
- John Byrd

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## LARP Instrumentation Group

- BNL
- Peter Cameron
- Angelika Drees
- FNAL
- Cheng-Yang Tan
- John Marriner
- LBNL
- John Byrd
- Bill Turner
- Peter Denes
- Massimo Placidi
- Alex Ratti
- Stefano De Santis
- Jean-Francois Beche
- Jim Greer
- Max Zolotorev

- CERN
- Hermann Schmickler
- Enrico Bravin
- Steve Hutchins
- Alan Burns
- Rhodri Jones
- Fritz Caspers
- Jean-Pierre Koutchouk
- Frederick Bordry
- University of Pavia
- Franco Manfredi
- Gianluca Traversi
- Lodovico Ratti
- Massimo Manghisoni

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## LARP will help the LHC in 3 key areas:
Bring LHC to full energy
	Betatron tune, coupling, and chromaticity control during ramp
Bring LHC to design luminosity
	Real-time luminosity monitor
LHC machine protection
	Longitudinal density monitors

*Bring LHC to full energy*
- 	Betatron tune, coupling, and chromaticity control during ramp
*Bring LHC to design luminosity*
- 	Real-time luminosity monitor
*LHC machine protection*
- 	Longitudinal density monitors

- LARP Beam Instrumentation and Diagnostic Techniques

- These contributions advance the state-of-the-art in beam instru-mentation and have direct contributions to present and future US accelerator projects.

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## High Bandwidth Luminosity Monitor

- Instrument US-built TAN absorbers to measure and optimize the luminosity of colliding bunch pairs with 25 nsec separation

-  Luminosity  *N*MIP from ***n*** shower
-  Crossing Angle  L+R

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## LHC Luminosity Monitor

- The challenge:
- High radiation environment (100 MGy/year)
- Bunch-by-bunch capability (25 nsec separation)
- The solution:
- Segmented, multi-gap, pressurized ArN2 gas ionization chamber constructed of rad hard materials

- 94 mm

- 9 cm

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Lumi Engineering Design

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Chamber built

- High pressure vesselSix-layer chamber with ceramic insulationRad-hard signal and HV cables

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Luminometer details

- Segmented, multi-gap, pressurized gas ionization chamber constructed of rad hard materials
- 3-11 atmospheres Ar + 2-6%N2 gas mixture, e- drift velocity 3.2 cm/s
- Low noise bi-polar transistor pre-amplifier “cold” cable termination, ENC ~ 1,824 e-
- Pulse shaper,  = 2.5 ns
- 3 m radiation hard cable between ionization chamber and front end electronics, radiation dose to electronics < 100 MGy/oper yr
- S/N ~ 5 for single pp interaction

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Instrumented TAN absorber

- IP

- Instrument a
*Copper Bar*

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Luminometer Beam Tests

- Use beam test facilities at the ALS to provide MIPs for the detector to test
- position sensitivity
- time response and gain
- accuracy
- operating experience over long time periods

- Booster-To-Storage Ring spur:
- 1.5 GeV e- at 1 Hz rate
- 30 psec pulse length
- intensity from 1 to 1e9 e- (1e3 typical)
- daily access and availability

- Storage Ring spill:
- 1.5 GeV e- with variable spacing
- 30 psec pulse length
- intensity of a few e-
- weekly access

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Position Sensitivity

- Raster scan detector through pencil beam
- Record 4 quadrants:
- x=(left-right)/sum
- y=(top-bottom)/sum

- y independent of x

- Ionization chamber works as a true 4-quadrant detector
- x and y are independent (no crosstalk)
- Position resolution < 110 μm

- x independent of y

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Detector response time

- Measure pulse response for varying pressure, gas mixture, and voltage.  Derive drift velocity from fit using electronics response.

- Pulses a bit longer than expected due to additional capacitance of detector/cable but still suitable for 25 nsec operation.

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Simulate LHC Conditions in the ALS

- ionization
- chamber

- lost electron

- removeable
- lead

- scraper

- electron bunches

- primary EM
- shower

- vacuum chamber

- Fill pattern adjustable with 2 nsec spacing into 328 buckets
- For example:
- 24 nsec->41.7 MHz, max 27 bunches
- 26 nsec->38.5 MHz, max 25 bunches
- LHC conditions: 25 nsec-> 40 MHz

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Fast Pulse Beam Test Results

**Gap**

**Gap**

- 52 nsec, 11 bunches

- 26 nsec, 22 bunches

- Spilled ALS beam provides a test of LHC conditions.

- Further studies to determine if pulses can be deconvolved to 1% accuracy.

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## LHC Longitudinal Charge Density 

- LHC beam carries 350 MJ. Beam loss in magnets can cause severe damage.
- Machine protection issues for study include:
- Debunched beam at injection
- Population in abort gap
- Ghost bunches
- Bunch core and tails
- Requirements:
- 104 dynamic range
- 20 samples/bunch giving ±21120 psec). Corresponds to 50 psec sampling resolution.
- Do this for all buckets (h=35640!). Drives overall sampling rate.

- The LDM will also be an invaluable tool for beam dynamics studies in LHC.

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## LHC Longitudinal Charge Density Specs

- Requirements (from. C. Fischer, LHC-BSRL-ES-0005.00 rev 2.0, 07 Jan 03)

- Two instruments

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Optical Sampling Technology

- Use mixing of synchrotron radiation with a short laser pulse to sample the longitudinal bunch profile

- Bunch

- Synchrotron
- Photons 1

- Laser
- Photons 2

- PMT

- Non-linear
- crystal
- [BBO]

- Filter(1+2)

- Proof-of-principle demonstrated on the ALS. Developed in collaboration with femtoslicing program.

- LHC beams (=7000) emit the same visible light as electron machines

- Effort not funded by LARP in FY04. Increase to 140k$ in FY05

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Abort Gap Monitor

- Effort not funded by LARP in FY04. Increase to 140k$ in FY05.

- Goal: detect presence of charge in gap for abort kicker rise time
- Possible solution: detect synch light with gated MCP/PMT.

- Similar approach used in light sources to measure parasite bunches.

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Initial Abort Gap Monitor Tests

- Gate signal on

- Parasitic bunch

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## LARP Structure

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## LARP Funding Profile

- Peak in FY07 (LHC startup)

- LBNL at 162k$ FY04

- John Byrd

- DOE HEP Review, 18-19 Feb 2004

## Summary

- US contribution to LHC instrumentation important for bringing LHC to full energy and maximizing luminosity. We have made tremendous progress on two critical items:
- Luminosity monitor
- prototype designed, built, and fully tested (almost!) to meet LHC specs
- allows measurement of bunch crossing pairs down to 25 nsec in high radiation environment
- Longitudinal Density Monitors
- helps LHC to safely reach full energy at full current
- laser mixing technique demonstrated
- abort gap monitor is feasible

- LBL has an ideal combination of experience in electro-optic technology, synchrotron radiation, accelerator physics and beam diagnostics to make unique contributions to LHC

- John Byrd

- DOE HEP Review, 18-19 Feb 2004