The AMO Instrument

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The AMO Instrument Science DriversJohn Bozek,
LCLS

• Scientific Program
• Sample source
• Spectrometers
• Diagnostics
• Laser
• Layout
• Future

2
Scientific Goals of the AMO instrumentation

• Investigate multiphoton and high-field x-ray
  processes in atoms, molecules and clusters
• Multi-photon ionization/excitation in
  atoms/molecules/clusters
• Accessible intensity on verge of high-field
  regime
• Study time-resolved phenomena in atoms, molecules
  and clusters using ultrafast x-rays
• Inner-shell side band experiments
• Photoionization of aligned molecules
• Temporal evolution of state-prepared systems

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Proposal Workshop

• Held June 2 3
• Over 60 attendees
• Presented teams scientific program and technical
  details of instrument
• Research interests included
• Aligned molecules Ryan Coffee, PULSE
• LCLS as a laser pump Nina Rohringer, LLNL
• Highly charged ions Peter Beierdorfer, LLNL
• Fundamental damage at high intensity Linda
  Young, ANL
• Imaging/x-ray emission Daniel Rolles, CFEL
• Single shot timing measurements Hamed Merdji,
  CEA
• Magneto-Optical trapped ColTRIMS Ali Belkacem,
  LBNL
• AMO experiments for biomolecular imaging Janos
  Hadju, SLAC Uppsala
• Time-resolved energy dispersive diffraction
  Valerio Rossi-Albertini, ISM-CNR

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Proposal Workshop

• Interest in using the AMO chamber as a vehicle
  for additional experimental capabilities
• Recommended increasing flange sizes on vacuum
  chamber
• Concern about gas density in interaction region
  with distance from jet to interaction region
• From Neumark whos used to using pulsed jet with
  cw-synchrotron source

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AMO Instrument Experimental Facilities

• Optics
• High Field Physics Chamber
• Gas jet
• Electron TOFs
• Ion spectrometers
• X-ray spectrometers
• Chamber, shielding, pumping, shutter, etc
• Diagnostics Chamber
• Magnetic bottle electron spectrometer
• Beam screens
• Pulse energy monitor
• Pulse picker

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AMO Instrumentation - Schematic
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AMO Instrument Design focusing optics

• Peak intensity depends on size of beam focus
  accessible physics depends on intensity

Focus W/cm2
1mm 71012
100µm 71014
10 µm 71016
1 µm 71018
100nm 71020

• Interaction region 140m from source
• Source _at_ 825 eV - 116mm
• Divergence _at_ 825eV - 5.7mrad
• Unfocussed beam diameter 1.1mm
• Focusing optics 1m from interaction region

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Focusing Optics Elliptical Bender

• Side shaping required to achieve best shape

Images courtesy of Alexis Smith YiDe Chuang,
LBNL
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Focusing Optics Elliptical Bender

• Optics can be reshaped for 2nd focus 1m
  downstream with slight increase in slope error

Images courtesy of YiDe Chuang, LBNL
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Focusing Optics Surface Coatings

• Regina Soufli _at_ LLNL has been working on
  methodology to achieve smooth B4C coatings
  slower deposition

• Increased surface stress, however, which may
  result in delamination

Image courtesy of Regina Soufli, LLNL
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Focusing Optics Mechanical Design
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Experimental station - Gas jet

• Pulsed valve type described by Proch Trickl,
  Rev. Sci. Instrum. 60, 713 (1989)

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Experimental station Pulsed Gas Jet
Skimmer
Gas jet chamber
X ray beam
Turbo pump
Interaction region
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Experimental station - Gas jet
Multiple skimmers configuration
Intermediate chambers
Gas jet chamber
X ray beam
Interaction region
Turbo pumps
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High Field Physics Ion Spectrometers

• Three different types of Ion Spectrometer
• Time-of-flight spectrometer using integrating
  metallic anode
• Wiley McLaren, Rev. Sci. Instrum., 26, 1150
  (1955).
• Velocity map imaging spectrometer using a
  phosphor screen to image impact location of ions
• Eppink Parker, Rev. Sci. Instrum., 68, 3477
  (1997).
• Momentum resolving spectrometer using a delay
  line anode to measure position and time of ion
  impact
• Dörner et al., Phys. Rep. 330, 95 (2000).

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High Field Physics Ion Spectrometers

• Ion spectrometers are interchangeable via common
  sized flange
• Similar schemes for mounting lenses/meshes
  flight tube
• Only integrating ion spectrometer will be used in
  first year

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High Field Physics eTOF

• Based on a successful design used by D. Lindles
  group at ALS designed for up to 5keV electrons
• Relatively flat transmission above 20eV KE

Figures from O. Hemmers et al., Rev. Sci. Instr.,
69, 3809 (1998)
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Experimentation station - ETOF
Magnetic shielding
Turbo pump
Electrical lens
Actuators
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High Field Physics eTOF

• Five electron spectrometers arrayed around
  interaction region

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Experimental station Chamber X-Section
eTOF
Gas jet port
Interaction region
Ion TOF
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High Field Physics X-ray spectrometers

• Two of the electron spectrometers can be removed
  replaced with x-ray emission spectrometers
• Spectrometers require high efficiency for diffuse
  gaseous targets
• Single shot capable detectors either CCDs/CMOS
  detectors directly or MCP amplified phosphor
  screen imaged with camera external to vacuum
• Two spectrometers a grating spectrometer for lt2
  keV and crystal spectrometer for gt2 keV
• Design not yet complete

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AMO Instrument - Diagnostics

• Diagnostics in a separate chamber with
• Magnetic bottle spectrometer
• Measures photon wavelength and bandwidth
• Can also be used to measure temporal overlap of
  FEL laser beam
• Total pulse energy monitor
• Measures pulse energy on each pulse
• Two beam screens
• Measures position size of beam
• Either geometric or coherent interference based

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Diagnostics Magnetic Bottle

• Magnetic field directs electrons to detector
  increasing collection efficiency
• As first described by Kruit Read, J. Phys. E,
  16, 313 (1983)

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Diagnostics Magnetic Bottle

• Single shot electron energy spectrum measure
  photon energy and bandwidth

Design courtesy of Chris Roedig (Lou DiMauros
group at OSU).
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Diagnostics Beam Viewing Screens

• Two screens separated by 1m to measure beam
  trajectory divergence
• 1st screen partially transparent 500mm of YAG
  on SiN membrane imaged with CCD (120Hz)
• Second screen can extinguish beam using a thick
  YAG crystal

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Total Energy (Thermal) Sensor provides
calibrated measurement of FEL pulse energy
Measures FEL energy deposition through
temperature rise
Cu heat sink
Thermistors Nd0.66Sr0.33MnO3 (On back of
substrate)
Sensor Temperature Rise
FEL pulse
K
0.5 mm Si substrate
t 0
t 0.25 ms
t 0.1 ms
Thermal diffusion of FEL energy
VG from R. Bionta
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Diagnostics chamber downstream
Magnetic bottle
Differential pumping
Beam profile monitor
Power monitor
Magnetic bottle magnet XYZ stage
Beam viewing screen
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NEH Laser
DIAGNOSTIC SUITE -Spectrometer -Autocorrelator -Fr
og -Beam Analyzer -Power Meters -Oscilloscopes
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NEH Laser System and Optical Transport
Laser Hall
Hutch 1
Hutch 2
Hutch 3
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Introducing Laser into AMO Chamber

• Laser introduced on-axis using mirror with hole
• All focusing/steering outside vacuum
• Laser beam diam. 20-60 um at interaction region

• Additional off-axis ports available to bring in
  laser at sharp angle, better defining interaction
  region
• Similar arrangement on diagnostic chamber

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Controls Data Acquisition

• EPICS will be used to control instrumentation
• All motions, voltages, etc. under remote control
• Test-stands already being built

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Controls Data Acquisition

• Acqiris DC282 high-speed 10-bit cPCI Digitizer
• 4 channels
• 2-8 GS/s sampling rate
• Acquisition memory from 1024 kpoints to 1024
  Mpoints (optional)?
• Low dead time (350 ns) sequential recording with
  time stamps
• 6U PXI/CompactPCI standard, 64 bit, 66 MHz PCI
  bus
• Sustained transfer rate up to 400MB/s to host SBC

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Layout of AMO experiment

• Design currently being finallizedcompletion in
  June

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Whats there July 2009?

• Focusing Optics
• High Field Physics Chamber
• Pulsed gas jet
• Ion TOF (Wiley McLaren type)
• Electron TOFs
• Diagnostics
• Effusive gas jet
• Magnetic bottle TOF
• Beam screens
• Synchronized Laser

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And whats commissioned later ?

• Pulse picker (12/09)
• High Field Physics Chamber
• Velocity map imaging ion spectrometer (10/09)
• Momentum resolving ion spectrometer (reaction
  microscope/ColTRIMS) (2/10)
• X-ray spectrometers (1/10)
• Diagnostics
• Pulse energy monitor (11/09)

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The Path Forward

• Preliminary Design Review Completed
• Finish detailing high field physics chamber,
  diagnostics
• Finalize Design Review July 08
• Procurement phase Aug-Dec 08
• Assembly Testing Jan-Jun 09
• Ready for first light July 09
• Lots of help from engineering, controls, etc.