Engineering Division1

MERLIN RIXS Endstation Design Review

Tom Miller6-30-08

90 Deg Scatter

Back Scatter

(proposed)

Forward Scatter

(proposed)

Sample prep

Main chamber Assy

Beam Direction

Engineering Division2

Basic layout of MERLIN RIXS Endstation

ARPES Endstation

RIXS KBMirrors

4.0.1 Experiments

Engineering Division3

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.

Engineering Division4

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.

Engineering Division5

Sample Prep

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

Basic sample garage design

Engineering Division6

Spectrograph and Slit Assembly Overview

Camera shown at minimum and

maximum working distance

Engineering Division7

Spectrograph FundamentalsThe 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.

Figure 2: Optical layout of the spectrograph.

977-1282mm977-1282mm

This Page courtesy of

Yi-De Chuang 5-20-08

Engineering Division8

Alignment, resolution and stability requirements for the spectrograph

Dimension Alignment tolerance Mechanical steps Design Resolution Stability tolerance

x 100m N/A 100m* 10m

y 100m N/A 100m* 10m

z 12.5m 2.5m (?) 0.1m 0.5m

x 1o (irrelevant) N/A <0.1o 0.1o

y 6mrad N/A <1mrad 0.6mrad

z 1o N/A <1rad** 0.1o

*Survey tolerance**This is a consequence of the Z-axis resolution

This Page courtesy of

Yi-De Chuang 5-20-08

See figure 1 for coordinate system

Engineering Division9

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 repeatabilitySlide on Y-strut allows high-precision

translation of grating or slit

Engineering Division10

Y axis translation Mechanism

Travel stops on slide prevent damage to slit assembly.

Engineering Division11

Spectrometer translation mechanism

Slide shown fully extended

Slide shown fully retracted. Note only one pinch point - at full extension.

Custom low-profile high rigidity crossed-roller slide.

Engineering Division12

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.

Engineering Division13

Spectrometer and slit assembly

The white spectrometer base plate allows complete off-line alignment of the mirror tank, slits and camera assembly.

Engineering Division14

Slit Fundamentals

If slits are used, the requirements are as follows:

• Minimum gap < 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 <=1 micron using manual micrometer heads

Engineering Division15

Slit Assembly

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

Translationbellows

Isolation bellows

Engineering Division16

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 >500 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.

Engineering Division17

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 LVDT’s, 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.

Engineering Division18

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.

Engineering Division19

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.

Slit Mechanism Mounting

Engineering Division20

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.

Engineering Division21

Camera Bellows Support

Low cost linear bushings ride on stainless guide rods.

Engineering Division22

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.

Engineering Division23

Seismic Calculations

RIXS Endstation

Seismic Calculations for Concrete Floor Anchors

DescriptionTotal

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 (<1)

Safety Factor

( > 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 1.32Non-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 2.15Non-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 1.61Non-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 4.34Non-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 1.65Includes 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 1.82Includes 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

  TensionTen. /

AnchorShear   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 5.52 1/2 2374 1798 7.0

2 9/16 5/8 3884 3447 9.03 3/16 3/4 5406 4862 11.0

<==

Engineering Division24

Questions and Observations