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Linac Beams for Linac Beams for Fixed Target ExperimentsFixed Target Experiments
Presentation by Roger EricksonPresentation by Roger Erickson
SLAC Operations ReviewSLAC Operations ReviewSLAC, June 15-16, 2004SLAC, June 15-16, 2004
06/16/04 Accelerator Operations Review
OutlineOutline
Linac and sourcesLinac and sources Interleaved beamsInterleaved beams A-Line and End Station A (ESA)A-Line and End Station A (ESA) Final Focus Test Beam (FFTB)Final Focus Test Beam (FFTB) Secondary Test BeamsSecondary Test Beams SummarySummary
06/16/04 Accelerator Operations Review
Linac Beam LinesLinac Beam Lines
LCLS will add an electron injector downstream of the positron source.
Fixed target experiments can be carried out in End Station A (ESA) or the Final Focus Test Beam (FFTB) facility.
06/16/04 Accelerator Operations Review
The Two-mile LinacThe Two-mile Linac
50 GeV Linac with multiple pulsed extraction points.50 GeV Linac with multiple pulsed extraction points. 120 pulses per second max; now running 30.120 pulses per second max; now running 30. Up to 6e11 electrons per pulse.Up to 6e11 electrons per pulse. Polarized electrons available up to full intensity.Polarized electrons available up to full intensity. 4e10 positrons per pulse, interleaved with electron 4e10 positrons per pulse, interleaved with electron
pulses.pulses. Long pulses (undamped) or short pulses (damped).Long pulses (undamped) or short pulses (damped). Typically running two programs simultaneously:Typically running two programs simultaneously:
• PEP-II• Fixed target in ESA or FFTB
Flexibility for interleaved beams: e+, e-, damped and Flexibility for interleaved beams: e+, e-, damped and undamped, different energies, intensities and rates.undamped, different energies, intensities and rates.
06/16/04 Accelerator Operations Review
Typical (Recent) Running ModeTypical (Recent) Running Mode
Linac runs well at 30 pulses/sec (half the ac line frequency).Linac runs well at 30 pulses/sec (half the ac line frequency).
9 GeV electrons to HER: on demand for trickling, up to 10 Hz.9 GeV electrons to HER: on demand for trickling, up to 10 Hz. 3.1 GeV positrons to LER: on demand for trickling, up to 10 Hz.3.1 GeV positrons to LER: on demand for trickling, up to 10 Hz. 28.5 GeV “scavenger” electrons to Sector 19 28.5 GeV “scavenger” electrons to Sector 19
(to make more positrons for the next cycle).(to make more positrons for the next cycle). 28.5 GeV electrons to FFTB: 10 Hz for fixed target programs28.5 GeV electrons to FFTB: 10 Hz for fixed target programs
(interleaved with PEP injection pulses).(interleaved with PEP injection pulses).
At the push of a button,At the push of a button, Electrons and Positrons to PEP-II for rapid filling at 15 Hz each Electrons and Positrons to PEP-II for rapid filling at 15 Hz each
(with no rate to FFTB).(with no rate to FFTB).
06/16/04 Accelerator Operations Review
Research Yard Experimental FacilitiesResearch Yard Experimental Facilities
ESA
FFTB
06/16/04 Accelerator Operations Review
A-Line to ESAA-Line to ESA
SLAC’s original experimental hall, site of parton discovery and SLAC’s original experimental hall, site of parton discovery and parity violation in eP scattering.parity violation in eP scattering.
Recent E-158 success: first observation of parity violation in Recent E-158 success: first observation of parity violation in polarized e-e- Moller scattering. polarized e-e- Moller scattering. E-158 had three production runs at 120 Hz in 2002-2003; E-158 had three production runs at 120 Hz in 2002-2003; once with PEP-II and twice alone.once with PEP-II and twice alone.
High power (500 kW) beam capability.High power (500 kW) beam capability. ESA is convenient for staging fixed target experimentsESA is convenient for staging fixed target experiments
• Large, massively shielded building.• Power, LCW, and cryogenic facilities.• Easy truck access.• Crane coverage.• Counting house with DAQ facilities.
Strong bends and weak focusing preclude “FFTB beams” with Strong bends and weak focusing preclude “FFTB beams” with small emittance and compressed bunch length.small emittance and compressed bunch length.
06/16/04 Accelerator Operations Review
Energy dithering region
BPM ~2 microns
energy ~1 MeV
Agreement (MeV)
BPM
24
X (
MeV
)
BPM12 X (MeV)
toroid ~30 ppm
A-Line Beam Monitoring DevicesA-Line Beam Monitoring Devices
06/16/04 Accelerator Operations Review
Parameter E-158 NLC-500
Charge/Train 5 x 1011 14.4 x 1011
Repetition Rate 120 Hz 120 Hz
Energy 45 GeV 250 GeV
e- Polarization 85% 85%
Train Length 270ns 267ns
Microbunch spacing 0.3ns 1.4ns
Beam Loading 13% 22%
Energy Spread 0.15% 0.16%
E-158 BeamE-158 Beam
Comparison with 500 GeV Linear Collider Design.
06/16/04 Accelerator Operations Review
End Station AEnd Station A
Photo Shows E-158 Spectrometer Magnets.
06/16/04 Accelerator Operations Review
Pending Programs in ESAPending Programs in ESA
Calibration of GLAST detector components Calibration of GLAST detector components
with secondary hadrons with secondary hadrons
(to be scheduled to accommodate GLAST requirements).(to be scheduled to accommodate GLAST requirements).
A Letter of Intent submitted to the EPAC:A Letter of Intent submitted to the EPAC:
Beam Instrumentation Tests for the Linear Collider Beam Instrumentation Tests for the Linear Collider
using the SLAC A-Line and End Station Ausing the SLAC A-Line and End Station A
06/16/04 Accelerator Operations Review
Final Focus Test BeamFinal Focus Test Beam
The FFTB was originally built to demonstrate technology for The FFTB was originally built to demonstrate technology for focusing and measuring sub-micron electron beams suitable for a focusing and measuring sub-micron electron beams suitable for a future linear collider.future linear collider.
Recent on-going programs include:Recent on-going programs include:
Plasma Wakefield Acceleration – a series of experiments that have Plasma Wakefield Acceleration – a series of experiments that have recently demonstrated high-gradient acceleration in a lithium recently demonstrated high-gradient acceleration in a lithium plasma.plasma.
SPPS – A new facility that uses compressed electron bunches to SPPS – A new facility that uses compressed electron bunches to generate intense x-ray pulses.generate intense x-ray pulses.Technology applicable to the LCLS:Technology applicable to the LCLS: Extreme bunch compression. Beam control and feedback for stability. Instrumentation for characterizing extremely short x-ray pulses.
06/16/04 Accelerator Operations Review
FFTB Experimental AreaFFTB Experimental Area
06/16/04 Accelerator Operations Review
RTL
DAMPINGRING
SLAC LINAC
9 ps 0.4 ps
50 ps
1 GeV 28.5 GeV
14-meter chicane compressor in linac at 1/3 point (9 GeV)
CHICANEBENDINGMAGNETS
LONGER PATHTAKEN BY HEAD OF THE BUNCH
Energy
e-
Energy
Time
ELECTRON BUNCH WITH HIGHER ENERGY TAIL
TAIL BEGINS TO CATCH UP
FULLY COMPRESSED
FFTB
Short Bunches in FFTB
06/16/04 Accelerator Operations Review
Plasma Wakefield Acceleration Plasma Wakefield Acceleration
e-
N=1.81010
z=20-12µmE=28.5 GeV
Optical TransitionRadiators
Li Plasma Gas Cell: H2, Xe, NO
ne≈0-1018 cm-3
L≈2.5-20 cm
Plasma light
X-RayDiagnostic,
e-/e+
Production
CherenkovRadiator Dump
∫Cdt
ImagingSpectrometer
EnergySpectrum“X-ray”
25m
CoherentTransition
Radiation andInterferometer
0 +5-5
ne=2.5x1017No Plasma
Gain
Loss
0 +5-5
7.9
GeV
≈3 GeV!
ne=2.5x1017
0 +5-5
Pyro=484
0 +5-5
+1.5 GeV
ne=3.5x1017No Plasma
Min.Gain
Min.Loss
0 +5-5
Rel
ativ
e E
nerg
y (G
eV)
06/16/04 Accelerator Operations Review
SPPS in FFTBSPPS in FFTB
06/16/04 Accelerator Operations Review
Photon beam line
Electron beam line
Experimental Area
Beamdump
FFTB Dump Line Experimental Area
06/16/04 Accelerator Operations Review
Pending Programs in FFTBPending Programs in FFTB
SPPSSPPSOngoing program of technology development involving extremely short x-Ongoing program of technology development involving extremely short x-ray pulses.ray pulses.
Plasma Wakefield AccelerationPlasma Wakefield AccelerationOngoing program to develop exotic new methods for achieving very high Ongoing program to develop exotic new methods for achieving very high accelerating gradients, strong plasma focusing, and related technology.accelerating gradients, strong plasma focusing, and related technology.
Experiment E-165Experiment E-165Flourescence in Air from Showers (FLASH)Flourescence in Air from Showers (FLASH)
A continuing program to quantitatively understand the production of light A continuing program to quantitatively understand the production of light by cosmic rays in the upper amosphere, using controlled laboratory by cosmic rays in the upper amosphere, using controlled laboratory conditions.conditions.
Experiment E166Experiment E166 A Proposal to Test Production of Polarized Positrons with the SLAC 50-GeV A Proposal to Test Production of Polarized Positrons with the SLAC 50-GeV Beam in the FFTBBeam in the FFTBAn undulator-based technique applicable to a future linear collider.An undulator-based technique applicable to a future linear collider.
06/16/04 Accelerator Operations Review
Test Beam FacilitiesTest Beam Facilities
Primary electron or positron beams to ESA or FFTB.Primary electron or positron beams to ESA or FFTB.
Secondary electron or positron beams to ESA or FFTB.Secondary electron or positron beams to ESA or FFTB.• Produced by double conversion (e- to gammas to e+ or e-).• One or a few particles/pulse.• Energy easily selectable with transport line magnets.
Secondary hadron beam to ESA.Secondary hadron beam to ESA.• Primary electrons to beryllium target near end of linac.• Secondary particles scattered at 0.5 deg into A-Line.• Positrons, pions, kaons, and protons tagged with time-of-flight and
Cerenkov detectors. One tagged particle/pulse was delivered to GLAST detector development test.
06/16/04 Accelerator Operations Review
Test Beam SchedulingTest Beam Scheduling
The approval and scheduling process is designed to minimize effort for outside The approval and scheduling process is designed to minimize effort for outside users and minimize cost and impact for SLAC.users and minimize cost and impact for SLAC.
Proposals are submitted to Experimental Facilities Department. EFD staff Proposals are submitted to Experimental Facilities Department. EFD staff provide technical and administrative support for users.provide technical and administrative support for users.
““Test Request” summary is circulated to:Test Request” summary is circulated to:• Radiation physicist• Chairman, Safety Oversight Committee• FFTB (or ESA) Area Manager• Accelerator Department physicist• Research Division Program Coordinator
Test Request is submitted to Accelerator Department Operations Section for Test Request is submitted to Accelerator Department Operations Section for scheduling.scheduling.
Beam Authorization Sheet is prepared by Radiation Physics Department.Beam Authorization Sheet is prepared by Radiation Physics Department.
Most test beam experiments are carried out with no significant adverse impact Most test beam experiments are carried out with no significant adverse impact on other programs. Many are done in 1 to 3 days.on other programs. Many are done in 1 to 3 days.
06/16/04 Accelerator Operations Review
Test Beam Experiments in FFTBTest Beam Experiments in FFTB
T-447T-447 Single Pulse Damage in Materials (Sept 2000)Single Pulse Damage in Materials (Sept 2000)T-448T-448 Magnified Optical Transition Radiation Test (Oct 2000)Magnified Optical Transition Radiation Test (Oct 2000)T-450T-450 Damage Test in Diamond for LCLS (Oct 2000)Damage Test in Diamond for LCLS (Oct 2000)T-451T-451 High Energy Neutron Spectra Measurement (March 2001)High Energy Neutron Spectra Measurement (March 2001)T-452T-452 STAR Endcap Calorimeter Detector Prototype Test (Jan 2001)STAR Endcap Calorimeter Detector Prototype Test (Jan 2001)T-453T-453 Radiation Damage in Diamond for LCLS (April 2001)Radiation Damage in Diamond for LCLS (April 2001)T-454T-454 Measurement of Neutron Spectra (June 2001)Measurement of Neutron Spectra (June 2001)T-455T-455 Measurement of the Calorimeter for the Local Polarimeter at Phenix/RHIC (Aug 2001)Measurement of the Calorimeter for the Local Polarimeter at Phenix/RHIC (Aug 2001)T-456T-456 Magnetization Dynamics in Magnetic Films (Sept 2001)Magnetization Dynamics in Magnetic Films (Sept 2001)T-457T-457 Measurement of Neutron Energy Spectra Using Bonner Multi-Sphere Spectrometer (June Measurement of Neutron Energy Spectra Using Bonner Multi-Sphere Spectrometer (June
2002)2002)T-460T-460 Characterization of Askaryan Effect in Rock Salt (June 2002)Characterization of Askaryan Effect in Rock Salt (June 2002)T-461 T-461 High Atmosphere Air Fluorescence (June 2002)High Atmosphere Air Fluorescence (June 2002)T-462 T-462 Magnetization Dynamics of Soft-Magnetic Films (June 2002)Magnetization Dynamics of Soft-Magnetic Films (June 2002)T-464 T-464 Correlation of Linac Transverse Deflection Cavity with FFTB Streak Camera (June 2002)Correlation of Linac Transverse Deflection Cavity with FFTB Streak Camera (June 2002)T-465 T-465 Magnetization Dynamics in the Sub-picosecond Time Scale (May 2003)Magnetization Dynamics in the Sub-picosecond Time Scale (May 2003)T-466 T-466 UCLA Electromagnetic Calorimeter (EMC) Prototype (May 2003)UCLA Electromagnetic Calorimeter (EMC) Prototype (May 2003)T-467T-467 Measurement of FFTB Backgrounds for E166 (Jan 2004)Measurement of FFTB Backgrounds for E166 (Jan 2004)T-468T-468 Diamond Detector Response (July 2003)Diamond Detector Response (July 2003)
Experiments not yet run:Experiments not yet run:T-469T-469 DIRC R&D ProgramDIRC R&D ProgramT-470T-470 DASH: Diamond Detectors for FLASHDASH: Diamond Detectors for FLASHT-471T-471 Incoherent Radio Emission from ShowersIncoherent Radio Emission from Showers
06/16/04 Accelerator Operations Review
ConclusionsConclusions
Extra linac pulses, not needed for PEP-II injection, can be delivered to End Extra linac pulses, not needed for PEP-II injection, can be delivered to End Station A or the FFTB facility for use by fixed target or “test beam” Station A or the FFTB facility for use by fixed target or “test beam” experiments.experiments.
We have seen a constant demand for these beams from a wide variety of We have seen a constant demand for these beams from a wide variety of users.users.
Small experiments can be set up and run with no adverse impact on the Small experiments can be set up and run with no adverse impact on the PEP-II program and with very little additional cost to SLAC.PEP-II program and with very little additional cost to SLAC.
Significant new physics results have been achieved, and a large number of Significant new physics results have been achieved, and a large number of detector technology development tests have been carried out.detector technology development tests have been carried out.
The FFTB will be dismantled in 2006 to make room for the Linac Coherent The FFTB will be dismantled in 2006 to make room for the Linac Coherent Light Source (LCLS). We are exploring possible replacement options.Light Source (LCLS). We are exploring possible replacement options.
The requests for test beams keep coming!The requests for test beams keep coming!