XTOD Update - SSRL · 2007. 10. 31. · X-TOD Update [email protected] October 30, 2007 UCRL-PRES-xxxxxxx Total Energy (Thermal) Sensor provides calibrated measurement of FEL pulse

Richard M. BiontaX-TOD Update [email protected] 30, 2007

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XTOD Update

Facility Advisory CommitteePhoton Breakout Session

October 30, 2007


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LCLS Layout

Linac

FEE (Front-End-Enclosure)Diagnostics

SOMSHOMS

UndulatorHall

NEH (Near Experimental Hall)

X-Ray Tunnel

FEH (Far Experimental Hall)


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XTOD Commissioning Diagnostics and Offset Mirrors in the Front End Enclosure (FEE)

Gas Detector

GasDetector

Gas Attenuator

Direct Imager(Scintillator) FEL Offset Mirror Systems

Fixed Mask

Beam Direction

SolidAttenuators

K SpectrometerSoft X-Ray Imager

Thermal Sensor

Slit Collimators


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FEE Diagnostic Hardware

Fixed Mask / Slit – On orderAttenuator – On orderGas Detector – On order (see prototype results)

K Measurement / Soft X-Ray imagerNeed to redo SCR

Thermal Sensor – in final designDirect imager – in final designControls – Mostly procured


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Windowless gas detector exploits N2photoluminescence

FEL

Primary photoelectrons cause N2 molecules to fluoresce in the near UV

N2 gas inletPhoto detector

Removable aperture

Photo detector Magnet coils


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Gas Detector Prototype under test at SSRL

Direct Imager Prototype

Ion ChamberGas Detector

Prototype

Ion Chamber

Beam Direction


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Prototype Gas Detector insert for measuring x ray induced photoemission of candidate wall materials


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Gas Detector signal vs. magnetic field at various pressures

0 50 100 150 200 25010-5

10-4

10-3

12:00: 2.1 Torr 4.1 Torr 8.0 Torr 14.5 Torr 28.0 Torr 50.1 Torr 100 Torr 200 Torr 375 Torr 723 Torr

PM

T S

igna

l (μW

/1012

8ke

V p

h)Magnetic Field (Gauss)

9:00: 2.1 Torr 4.0 Torr 8.0 Torr 14.6 Torr 28.1 Torr 50.1 Torr 104 Torr 198 Torr 372 Torr 720 Torr

CHROMA filter, 8.2 keV (in tune), no insert

0 50 100 150 200 250105

106

107

108

Num

ber

Magnetic Field (Gauss)

p (Torr) 2 4 8 14 28 50 100 200 400 760

{Total # UV photons from gas} x {QEPMT}/{QE365nmPMT } x {Tfilter}

Simulated Measured

Simulation and measurement, when expressed in units of number of UV photons at detector, agree to within a factor of 2


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UV signal closely represented by 9:00, B on (red): Al is the best

graphite PMMA Al Si Cu silica Be Au holder SS sapphire105

106

107

108

109graphite PMMA Al Si Cu silica Be Au holder SS sapphire

graphite PMMA Al Si Cu silica Be Au holder SS sapphire

graphite PMMA Al Si Cu silica Be Au holder SS sapphire

1.3x10-5

1.3x10-4

1.3x10-3

1.3x10-2

1.3x10-1

PMT

Sign

al (#

UV

ph/1

012 8

keV

ph)

9:00, B off 9:00, B on 12:00, B off 12:00, B on

# U

V p

hoto

ns in

to 2π

/ x-r

ay p

hoto

n

Measured luminescence of solids at 8 keV

Al


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0 5 10 15 200

2x107

4x107

6x107

e

nerg

y de

posi

tion

rate

(keV

/ns)

time (ns)

energy deposited into N2

walls end caps

UV signal withinX rays scattered into walls ~ 1 ns

Photoelectrons hitting end caps 0 – 15 ns

X rays scattered into detector window ?Photoelectrons hitting walls 0 – 18 ns

Secondaries hitting walls and end caps 0 – 200 ns (?)Energy of photoelectrons deposited into N2 0 – 45 ns

Time dependence of gas detector signal from the 8keV fundamental

0 20 40 60 80 1000

2x107

4x107

6x107

UV

pho

tons

(arb

. uni

ts)

time (ns)

signal from N2 (τ~25ns) walls (τ~1ns) end caps (τ~1ns)

relative amplitude of curvesis not known

signalto bemeasured


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Gas Detector Final Design

AvalanchePhotodiode

Photo Multiplier Tube

Magnet Coils

Pressure sensors

Gas inlet / flow control

UV quiet liner


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840 eV < Eγ < 860 eV hν1= 844.6 eV

effective bandwidth = 5 5*10-3

2 x 1010 photons, total 2.6 x 10-6 J, total

7.8 x 10-7 J/cm2, center

Indirect imager finds spontaneous core

Vacuum chamber

Princeton Instruments back illuminated CCD camera25 x 25 mm chip, 20 um pixel size

ML mirror 8% reflectivity, 1% bandwidth

Raw soft spontaneous After reflection

Status Indirect Imager:PRD doneSCR redo


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Channel-cut Si Monochrometer will be used to measure relative K of two undulator segments

Linac E variation andmeasurement

Monochrometer

Detector

Detector monochrometer

measures intensity at a single point

Use linac E variation and measurement to obtain other points along curve

Two undulatorspontaneous spectrum. Falloff of high energy tail is independent of aperture

Two undulatorspontaneous high energy falloff has highest slope when ΔK/K=0. Status K Spectrometer:

PRD doneSCR redo


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Total Energy (Thermal) Sensor provides calibrated measurement of FEL pulse energy

ThermistorsNd0.66Sr0.33MnO3

(On back of substrate)

FEL pulse

Cu heat sink

0.5 mm Si substrate

Measures FEL energy deposition through temperature rise

t = 0t = 0.1 ms t = 0.25 ms

Thermal diffusion of FEL energy

Sensor Temperature Rise

[K]

Status Thermal Sensor:PRD doneSCR donePDR donePrototype doneFDR in progress


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Thermal sensor plagued by “prompt” pulse that is difficult to suppress

Absorbed Laser Energy, μJ Absorbed Laser Energy, μJ

ΔT

, °Κ

ΔT

, °Κ

At 100 μsec At 3 msec

Finite difference prediction

Measured data


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Epoxy

Slow Thermal Sensor:Slow speed with epoxy joint

Backup thermal sensor: Slow down response, average pulses

Thermistor(Top, ∂R/∂T)

FEL (Etotal)


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Slow sensor: Response is thermal, and linear with E

Response linear over three decades

Peak Temperature vs. Laser Pulse Energy

Sensor Resistance vs. Temperature

Response changes with TCR


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Thermistor(Top, ∂R/∂T)FEL (Etotal)

Heat sink(Tbath)

Substrate (heat capacity C, speed)

Trenches/bridges

Epoxy

Basic TEM design:fast, sensitive, rad hard, but affected by artifacts

Medium speed TEM:~100 µm bridges.

slow enough?

Slow TEM:Adjust speed with epoxy.

too slow?

The Options: Same sensor technology, different speeds


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Direct Imager, preliminary designSingle shot measurement of

f(x,y), x, y ,u

Camera

Scintillators

Status Direct Imager:PRD doneSCR donePrototype donePDR donein Final Design


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Absorbed in 1 mm YAG, Maximum ~ 140,000 photoelectrons/pixelFull Well: 200,000Camera: Photometrics 512BObjective: Navitar Platinum 50

Power: 0.1365NA: 0.060

Soft X-Ray spontaneous, all undulator segments, thick scintillator


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Objective: Navitar Platinum 50Power: 0.1365NA: 0.060

Absorbed in 5 um YAG, Maximum ~ 20,000 photoelectrons/pixel Camera: Photometrics 512B

Soft X-Ray Spontaneous all undulatorsegments, thin scintillator


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Objective: Navitar Platinum 50Power: 0.1365NA: 0.060

Camera: Photometrics 512B

Absorbed in 5 um YAG, Maximum ~ 3.7e+8 photoelectrons/pixel

Soft X-Ray FEL signal, thin scintillator


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Absorbed in 1 mm YAG, Maximum ~ 1,800 photoelectrons/pixel Full Well: 200,000Camera: Photometrics 512BObjective: Navitar Platinum 50

Power: 0.1365NA: 0.060

Soft x-ray spontaneous, first undulator segment, thick scintillator


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Scintillator signals in FEL equivalents

CCD Range

YAG Range

Needed x-ray

attenuation

Needed x-ray

attenuation

Need x-ray attenuation of > 100 and visible attenuation of > 10

Needed visible

attenuation


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Direct Imager SSRL Run to measure YAG::Ceyield, Nov. 6-8, 2007

Vacuum window

Cascade

YAG*

WFOV Optic

NFOV Optic

Ion chamber

X-ray filtersCrossed

wires

Ion chamber

Beam line 2-2

Pulnix

*YAGs are the parts from Sant-Goban1) 12 mm x 12 mm x 1 mm2) 25 mm x 25 mm 5 micron


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FEE Racks are being loaded and wired


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Offset Mirror SystemCollimators – in final designSOMS – Mirrors purchased June 1st

Mount will follow HOMS designHOMS

Mirrors in final designPlan to purchase by December 30

Mount in preliminary designProblems with 50 nRad stability requirement

Pop-in Alignment CamerasProcurement delayed until FY09FOV’s and positions establishedPulnix 4200 camera under test at LLNLConceptual hardware design in progress


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FEL Offset Mirror Systems

SOMS and HOMS reflect horizontally


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FEL Offset Mirror Systems and “Pop-in”imagers for alignment

P PP P

P

P


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Differences between FEL offset mirrors and synchrotron mirrors

Multi KW power loading seen at synchrotrons not an issue at LCLS

Instead we worry about single shot damage from FELActive bending of Mirrors

Used at synchrotrons to make 100m radii for focusingNeeded at LCLS (HOMS) to maintain > 1 Mm radii so as to not change FEL divergence

Pointing stabilityStringent requirements for HOMS for a steady beam in the FEH


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SOMS mirrors are coated with B4C

t = 500 Å, θ = 13.9 mrad, σ = 4.5 ÅAt least ~ 90% up to 2.0 keVGood 3rd harmonic rejection

Primary pass-band

3rd harmonicpass-band

Status SOMS:PRD doneSCR doneMirror PDR doneMirror FDR doneMirrors in Purchase / Fabrication


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HOMS mirrors will be coated with SiC

(t = 500 Å)

(t = 500 Å)

Status HOMS:PRD draftSCR 7/17


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Pop-in alignment camerasPulnix 4200 2k x 2k

1 mm thick YAG::Ce, up to 60 mm x 60 mm


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SOMS Run025

Pop-in 1 (After SOMS Mirror 1)

Reflected off Mirror 1

Misses Mirror 1

~1000 photoelectrons / per pixel / pulse, likely need to integrate over 10 pulses

Camera: Pulnix TM-4100GE

Lens: Schneider Navitar Platinum 50

Power: 0.2526NA: 0.100

2 keV fundamental1 mm YAG, Full Well: 40,000

We are studying expected signal levels in the Pop-in cameras


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2 keV fundamental1 mm YAG, Full Well: 40,000

Camera: Pulnix TM-4100GE

Lens: Schneider Navitar Platinum 50

Power: 0.2526NA: 0.100

~1000 photoelectrons / per pixel / pulse, likely need to integrate over 10 pulses

Pop-in 2 (After SOMS Mirror 2)


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XTOD elements in Near Hall

Hard X-Ray Vacuum transport line stay-out

barrier

This section will not be installed but is planned for in case of delays in the installation of LUCI equipment

Collimators


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Status Tunnel:PRD doneSCR donePDR doneESD doneFDR done

XTOD Tunnel Design Complete


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Integrated EPICS control system for XTOD has been designed


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SummaryProgress continues on XTOD :

Procurement - Slit, Fixed Mask, Attenuator, Gas Detector In final design– Direct Imager, Thermal Detector, collimators, HOMS mirrorsIn preliminary design – Mirror mechanical, In conceptual design – K Spectrometer, Soft x-ray imager, Pop-in Alignment system

Problem areasThermal sensor signal degraded by non-thermal prompt signalSoft x-ray imager and K spectrometer design laggingHOMS pointing stability challenging

FEE diagnostic instrumentation will be ready for instillation in 2008

Documents

XTOD Update - SSRL · 2007. 10. 31. · X-TOD Update [email protected] October 30, 2007 UCRL-PRES-xxxxxxx Total Energy (Thermal) Sensor provides calibrated measurement of FEL pulse