MERLIN RIXS Endstation Design Review

1
MERLIN RIXS Endstation Design Review
Forward Scatter (proposed)
90 Deg Scatter
Back Scatter (proposed)
Sample prep
Beam Direction
Main chamber Assy
Tom Miller 6-30-08
2
Basic layout of MERLIN RIXS Endstation
ARPES Endstation
RIXS KB Mirrors
4.0.1 Experiments
3
RIXS Endstation

• Chamber includes 3 ports for spectrometers at 45,
  90 and 150 degrees. The sample transfer port is
  at 195 degrees. A John Pepper designed cryostat
  sits on top of a 150mm travel XYZ stage mounted
  on an 8 rotary axis. The rotary axis is limited
  to 270 degrees of total travel.

4
RIXS Support and Pumping Details

• Stand is designed for maximum rigidity with
  allowable footprint. The shear plate is not
  shown.

The pumping tree will initially have a 150 l/s
pump installed, but the support is designed for
a double-flanged 300 l/s model.
5
Sample Prep

• Sample prep with a loadlock chamber. View ports
  give views of transfers between chambers.

Basic sample garage design
6
Spectrograph and Slit Assembly Overview
Camera shown at minimum and maximum working
distance
7
Spectrograph Fundamentals

• The slitless emission spectrograph will be used
  at the MERLIN branch line to perform the resonant
  inelastic X-ray scattering spectroscopy (RIXS) at
  the transition metal M edge (30-150eV). The
  schematic plot of the spectrograph is shown in
  figure 1.

Figure 1 Schematic plot of the slitless VLS
spectrograph that will be used at MERLIN
beamline. This spectrograph has two optical
components a spherical focusing mirror and two
VLS plane gratings (central line density 2000 and
3000 l/mm). The optical design is shown in figure
2.
977-1282mm
This Page courtesy of Yi-De Chuang 5-20-08
Figure 2 Optical layout of the spectrograph.
8
Alignment, resolution and stability requirements
for the spectrograph
See figure 1 for coordinate system
Dimension Alignment tolerance Mechanical steps Design Resolution Stability tolerance
x 100mm N/A 100mm 10mm
y 100mm N/A 100mm 10mm
z 12.5mm 2.5mm (?) 0.1mm 0.5mm
Qx 1o (irrelevant) N/A lt0.1o 0.1o
Qy 6mrad N/A lt1mrad 0.6mrad
Qz 1o N/A lt1mrad 0.1o

Survey tolerance This is a consequence of the
Z-axis resolution
This Page courtesy of Yi-De Chuang 5-20-08
9
Spectrometer Stand
Kinematic base plate allows spectrometer to be
removed and replaced with high accuracy.
Spectrometer mounts with one shoulder bolt and
compression spring for safety and repeatability
Slide on Y-strut allows high-precision
translation of grating or slit
10
Y axis translation Mechanism
Travel stops on slide prevent damage to slit
assembly.
11
Spectrometer translation mechanism
Custom low-profile high rigidity crossed-roller
slide.
Slide shown fully extended
Slide shown fully retracted. Note only one pinch
point - at full extension.
12
Spectrometer Optics Chamber mounting
Drilled and tapped mounting bars will be welded
to .38 thick tank bottom. Tank was originally
held by clamps on input and output tubes. Note
bosses for 3-point mounting.
13
Spectrometer and slit assembly
The white spectrometer base plate allows complete
off-line alignment of the mirror tank, slits and
camera assembly.
14
Slit Fundamentals

• If slits are used, the requirements are as
  follows
• Minimum gap lt 5 microns, maximum 400 microns
• Mechanism must fit inside the radiation shielding
  of the cryostat
• Be insertible to within 5mm of the sample
• Be retractable to allow the Main chamber to be
  valved out prior to removal of the spectrograph.
  Total motion required is 9.75.
• Fit inside a 1.87 ID port with clearance to move
  /-0.1 in Y
• Have step resolution for gap of lt1 micron using
  manual micrometer heads

15
Slit Assembly
Isolation bellows
Translationbellows

• The 2 unused ports in the cross will be used for
  roughing out the slit and potentially for LVDT
  connector(s).

16
Slit Details

• Stop plate on actuation end of slit assembly has
  4-40 stop holes top and bottom to prevent over
  closing. Plate itself functions as a stop in the
  open direction. Slit will open gt500 microns if
  the levers are driven to the stops, but no damage
  will result. Round holes in stop plate are for
  LVDT wires. Levers are inserted into the assembly
  from the actuation end with the stop plate
  removed.

17
Slit Lever Details
Levers are made from 6061-T6 and are identical
top and bottom. Note ball seat and extension
spring hole on actuation end. Also note ledge at
blade end to prevent blade damage by
over-closing. Slit is fully closed in the relaxed
state. The stress on the 17-4 strip flexures when
open to 500 microns is about 75 ksi. Levers will
include provisions for LVDTs, but none will be
installed initially. The LVDT mounting location
will yield true slit opening if one LVDT is used
or relative blade locations (yielding gap and
position of gap) if 2 are used.
18
Slit Feedthrough Detail

• Tension spring keeps the lever loaded against the
  micrometer and the compression spring nearly
  cancels the vacuum loading from the bellows. This
  allows the micrometer to see a 3 lb thrust when
  under vacuum. At air, the required thrust is 6
  lb. Gold cylinder is a linear bearing. Orange
  disk is a shim that allows large adjustments of
  the micrometer zero. Small changes are made by
  moving the micrometer in the clamp. Green-gray
  spring mount slips into cross.

19
Slit Mechanism Mounting

• The slit mechanism is independently alignable to
  the spectrometer. The opposing bellows make this
  alignment independent of vacuum forces. The 4
  tooling balls on the mirror tank will be
  fiducialized to the grating. The position of the
  slit can then be related to the tooling balls.

20
Spectrograph Camera

• Camera is mounted to a standard 12 travel slide.
  Slide includes a linear encoder, index mark and
  limit switches. White shim plates allow alignment
  of the camera spool to the exit flange of the
  mirror tank.

21
Camera Bellows Support

• Low cost linear bushings ride on stainless guide
  rods.

22
Slit to Cryostat Relationship

• Note the intrusion of the slit into the cryostat
  assembly during use. Hard stops on the
  manipulator Y-axis will be required.

23
Seismic Calculations
RIXS Endstation
Seismic Calculations for Concrete Floor Anchors Seismic Calculations for Concrete Floor Anchors Seismic Calculations for Concrete Floor Anchors Seismic Calculations for Concrete Floor Anchors Seismic Calculations for Concrete Floor Anchors


Description Total Weight W, (lbs.) Horizontal Acceleration, Wx0.7 (lbs.) Height H, (in.) Distance D, (in.) Leverage Ratio, (D/H) Number of Anchors Tension Load (lbs.) Tension Load per Anchor (lbs.) Shear Load per Anchor (lbs.) Anchor Size (Dia, in.) Anchor Type (HDI) Allowable Tension Load per Anchor (lbs.) Allowable Shear Load per Anchor (lbs.) Combined Shear Tension Load Factor (lt1) Safety Factor ( gt 1) Notes
RIXS Spectrometer assy (5 anchors actual) 1300 910 37 28.00 1.32 2 1203 1203 455 1/2 HDI 2374 1798 0.76 1.32 Non-symmetrical pattern. Assumes one anchor restricting rotation about a line formed by 2 other anchors. Very conservative case. Actual shear loads would be 40 of calculated value.
RIXS Spectrometer assy (5 anchors actual) 1300 910 37 21.00 1.76 4 1603 802 228 1/2 HDI 2374 1798 0.46 2.15 Non-symmetrical pattern. Assumes two anchors restricting rotation about a line formed by 2 other anchors. Conservative case.
RIXS Sample Prep (2 anchors and 4 1/2" bolts) 700 490 33 14.00 2.36 2 1155 1155 245 1/2 HDI 2374 1798 0.62 1.61 Non-symmetrical pattern. Assumes one anchor restricting rotation about a line formed by one anchor and one bolt. Actual shear loading is 33 of calculated value.
RIXS Sample Prep (2 anchors and 4 1/2" bolts) 700 490 33 21.00 1.57 4 770 385 123 1/2 HDI 2374 1798 0.23 4.34 Non-symmetrical pattern. Assumes two anchors restricting rotation about a line formed by two bolts. Actual shear loading is 66 of calculated value.
RIXS Main Chamber assy Prep (7 anchors total) 2400 1680 29.5 28.00 1.05 4 1770 885 420 1/2 HDI 2374 1798 0.61 1.65 Includes moment induced by prep system. Non-symmetrical pattern. Assumes two anchors restricting rotation about a line formed by two anchors. Conservative case.
RIXS Main Chamber assy Prep (7 anchors total) 2400 1680 29.5 33.00 0.89 4 1502 751 420 1/2 HDI 2374 1798 0.55 1.82 Includes moment induced by prep system. Non-symmetrical pattern. Assumes two anchors restricting rotation about a line formed by two anchors. Conservative case.
    Acceleration     Lever. Ratio   Tension Ten. / Anchor Shear   HDI     Shear,Ten. Safety Factor


Hilti Drop in Anchors, Type HDI        
Max Depth (in.) Anchor Size (Dia, in.) Tension Load Allowable (lbs.) Shear Load Allowable (lbs.) Minimum Spacing (in.)
1 9/16 3/8 1483 1210 5.5
2 1/2 2374 1798 7.0
2 9/16 5/8 3884 3447 9.0
3 3/16 3/4 5406 4862 11.0


lt

24
Questions and Observations