Preliminary
Design Report
Phase I & II Insertion Device
Beamlines
NE-CAT
August 2003
Malcolm Capel
NE-CAT Lead Scientist,
Associate Director for beamline technology
CONTENTS
2.
Design chANGES FROM cONCEPTUAL dESIGN
3. BEAMLINE TECHNICAL SPECIFICATIONS
The
principal aims of the NE-CAT collaboration are the design, construction
and operation of undulator and bending magnet-based beamlines
for biological crystallographic data collection. Said beamlines will
be highly automated, possess
high brilliance and narrow band pass suitable for optimized MAD crystallographic
data collection. The resulting beamlines will
be used mainly in support of NIH National Centers for Research Resource
(NCRR)-funded
core scientific collaborations. The
core scientific collaborations involve a wide range of structural interests
including: biological signal transduction,
DNA transcription (initiation and regulation), cell cycle regulation, virus
structure and function, protein folding and protein synthesis (ribosome structure).
NE-CAT will also reserve a portion of operational time to support biological
crystallography by independent researchers.
The
main technological challenge of the NE-CAT NCRR proposal is the use of the
tandem-offset undulator concept to increase the
number of concurrently-operating undulator beamlines at a single APS sector. We intend to develop three beamlines using the tandem-canted undulator
strategy and a single bending magnet-based beamline. Our current planning is based on use of a pair
of 3.3 cm period undulators, 2.07 meters in length
with an angular offset of 1.0 milliradian. Beamline construction
will be split into four phases, summarized in Table 1.1. Note: for reasons delineated below the order
of construction of the four sector 24 beamlines
and the nomenclature used to refer to them have changed since submission of
the NE-CAT Conceptual Design Report (see first column, Table 1.1).
Table 1.1: Description of NE-CAT Beamlines and
Build-Phases
| Build Phase Designation PDR CDR |
Source |
|
Energy Resolution DE/E
@ 12.7 KeV |
Focus
Spot Size m
HWHH |
End Station Identifier |
Flux (focused) @ 12 KeV Phot/mm2/sec |
| I I |
|
5 – 25 |
1 x 10-4 |
100 x100 |
ID-C |
1014 |
| II III |
D.S. ID |
12.66 OR 14.78 |
2 x 10-4 |
100 x 100 |
ID-E |
1014 |
| III IV |
BM |
6 – 17 |
2 x 10-4 |
500 x 500 |
BM-B |
1011 |
| IV II |
D.S. ID |
9 – 17 |
2 x 10-4 |
100 x100 |
ID-D |
1014 |
Key:
D.S.
ID: Downstream undulator
BM: Bending
magnet
Figure
1.1 shows a schematic of the optical trains for the 3 sector 24 insertion
device beamlines, indicating the positions of all
main optical elements. The following
list details the overall performance goals for all 4 sector 24 beamlines:
1) Phase I: “Pass-Through” Undulator
Beamline. The first beamline
developed (using the upstream, outboard-projecting undulator)
will consist of a single optical train, supplying a single experimental endstation with doubly focused monochromatic light from 5
to 25 KeV, with a nominal band pass of order 10-4
(DE/E). Monochromitization
will be accomplished by a cryogenically-cooled double crystal Silicon Bragg
monochromator. A Kirkpatrick-Baez
(K-B) mirror pair will focus the monochromatic beam.
2) Phase II: “Single-Crystal Side-Bounce Undulator
Beamline. A single,side-bounce cryogenically-cooled 220 silicon monochromator will accept the residual beam from a diamond-transmission
monochromator using beam from the downstream, inwardly projecting
undulator (see Phase IV, below). The side-bounce
mono will deliver a monochromatic beam near 12.6 KeV,
with a nominal take-off angle (2θ) of 29.54o from the centerline.
The 220 Si crystal
will be mounted on a cooling stage that incorporates a vertical translation.
A second silicon crystal (311-cut) will be mounted on this stage, with
independent roll and pitch fine adjustments such that a second energy (14.78
KeV) will be selectable by a vertical translation of the cooling
stage (following the same 29.54o take off angle provided by the
220 crystal). This beamline will also use K-B focusing.
3) Phase III: Bending Magnet Beamline. The fourth beamline
developed by NE-CAT will use the bending magnet port of the assigned sector.
The phase III beamline will incorporate a water-cooled
Si-111 monochromator with sagittal focusing, providing a spectral range from 5 to 17
KeV (2 eV bandpass).
Vertical focusing will be accomplished with a mechanically figured mirror.
4) Phase IV:
Tunable Large-Offset, Side-Bounce Undulator Beamline. A pair of beamlines
will be sourced by the downstream, inboad-projecting
undulator. Monochromatization and physical separation of the Phase I
and Phase III beamlines will be accomplished with
a large horizontal-offset (1.5m) diamond transmission monochromator,
with a spectral range between ~8.5
and17 keV. The
undiffracted radiation is passes on to the Phase
II Fixed-Energy Side-Bounce monochromator. As with Phases I and II, Phase III will use
K-B focusing.
This document presents a detailed preliminary design for Phases I and II only. Separate PDR’s for the proceeding phases will be submitted for review during the current calendar year. The Phase IV beamline will be developed during the first renewal phase of our NCRR funding. We do, however, present preliminary, overall hutch layout and conceptual beamline design “sketches” for the side station and bending magnet beamlines in the present document.
2. Changes Since Submission of Conceptual Design
Report.
Three major
changes in our optical design have occurred since submission of our Conceptual
Design Report in spring of 2002. None
of these changes have substantively altered the overall beamline
layout or long-term work plan. These changes are enumerated below:
1) We have reassigned the upstream and downstream undulators
to different beamlines. Originally, we had planned on sourcing the Phase
I undulator beamline with
the downstream, inwardly projecting undulator and
Phase II and IV (PDR teminlolgy) with the upstream
undulator. We
realized that it will be far easier to accommodate the Phase II and Phase
IV (PDR nomenclature) monochromators if they are
situated inboard of the Phase I beam. With
this reassignment of the undulators, the mechanical
mounts and cooling systems for Phase II and IV monochromator
elements will be oriented away from the Phase I (outboard) undulator
beam, minimizing stearic clash between Phases I,
II and IV. The only significant effect
of this design change is in the placement of the penetrations in the first
and secondary optics enclosures.
2) In our CDR we planned on using diamond-based monochromators
in all NE-CAT insertion device beamlines. A patent encroachment suit has been filed by
General Electric Corporation against the one commercial diamond vendor capable
of sourcing diamonds of the requisite optical quality and size (
3) An additional tungsten bremsstrahlung collimator (located in the FOE) has been added
to simplify the horizontal shielding plan.
4) The length of 24-ID-B has been reduced by 10” on the upstream side to increase the width of the secondary egress path between 24-ID-B and 24-ID-D.
3. Beamline Technical Specifications.
All
four sector 24 NE-CAT beamlines are single-purpose,
fixed configuration macromolecular crystallography beamlines. The following functional elements must be provided by the various beamline subsystems:
· Shielding and safety systems must include enclosures for the optics and
the experimental hardware and be capable of protecting personnel from radiation
and equipment from such faults as loss of power, cooling fluid, etc.
· Optics systems must be capable of delivering a focused monochromatic beam
with long-term positional stability to a sample 40-60 meters from the radiation
source. The required positional stability
region (horizontal and vertical) is a square of edge length 10 microns with
a characteristic time measured in hours.
· Beam transport systems must convey the beam from the sector front end to
the sample position via ultra high vacuum paths to minimize intensity loss
(due to absorption) and scattering background.
· Utility systems must provide conventional infrastructure such as plumbing
of water and compressed gases; electrical power; HVAC capability; liquid nitrogen;
and mechanical support.
· Control systems must provide interactive (and secure) local and remote
control of all optics, sample handling and detection subsystems.
· Front ends, insertion devices and dipole magnet must provide an X-ray beam
with an energy range of at least ~5KeV to ~30 KeV.
· The lab and office module must provide for mechanical equipment setup and
maintenance; wet laboratory capability for sample preparation; and office
space for operations staff and data reduction.
The required performance
characteristics for the four NE-CAT sector 24 beamlines
are:
3.1 Phase
I “passthrough” beamline,
using outboard-projecting undulator:
·
An energy range of 5-25keV.
·
An unfocused beam of approximately 1012 X-rays/mm2/sec
to a sample about 65 meters from the source.
·
A focused beam of approximately 1014 X-rays/mm2/sec
to a sample about 65 meters from the source.
·
A focal spot size using mirrors of <100 μm horizontal by <100
μm vertical.
·
A beam with an energy bandwidth of ΔE/E ~1 x 10-4 at an energy of ~12.66
keV.
·
A beam that is stable to <10% of its size (e.g., a 100 μm beam will have a positional
stability of 10 μm).
3.2 Phase II single-crystal
side-bounce beamline using the inboard-projecting
undulator:
·
A fixed energy at
~12.66KeV or 14.78 KeV,
with a fixed take-off angle (2θ) of 29.54o.
·
An unfocused beam of approximately 1012 X-rays/mm2/sec
to a sample at 58 meters from the source.
·
A focused beam of approximately 1014 X-rays/mm2/sec
to a sample at 58 meters from the source.
·
A focal spot size using mirrors of <100 μm horizontal by <100
μm vertical.
·
A beam with an energy bandwidth of ΔE/E <2 x 10-4 at an energy of
~12.66 keV.
·
A beam that is stable to <10% of its size (e.g., a 100 μm beam will have a positional
stability of 10 μm).
3.4 Phase III bending magnet
beamline:
·
An energy range of ~5-17keV.
·
An unfocused beam of approximately 1010 X-rays/mm2/sec
to a sample about 35 meters from the source.
·
A focused beam of approximately 1011 X-rays/mm2/sec
to a sample about 35 meters from the source.
·
A focal spot size (using either zone plates or mirrors) of <500 μm horizontal by <300 μm vertical.
·
A beam with an energy bandwidth of ΔE/E <4 x 10-4 at an energy of
~12 keV.
·
A beam that is stable to <10% of its size (e.g., a 500 μm beam will have a positional
stability of 50 μm).
3.5 Phase IV diamond-transmission
beamline, using the inboard-projecting undulator:
·
An energy range of ~8.5-17keV.
·
Horizontal offset of monochromatized beam by
1.5 m.
·
An unfocused beam of approximately 1012 X-rays/mm2/sec
to a sample about 42 meters from the source.
·
A focused beam of approximately 1014 X-rays/mm2/sec
to a sample about 42 meters from the source.
·
A focal spot size using mirrors of <100 μm horizontal by <100
μm vertical.
·
A beam with an energy bandwidth of ΔE/E <2 x 10-4 at an energy of
~12.66 keV.
·
A beam that is stable to <10% of its size (e.g., a 100 μm beam will have a positional
stability of 10 μm).
3.6 End Stations
The sector 24 endstations will incorporate similar
designs and subsystems used in the NE-CAT 8BM endstation. The principal components of all four endstations are:
·
Collimation system, consisting of two independent arrays of pairs of vertical
and horizontal slit blade pairs, separated by ~ 1 m. Individual slit blade positions WILL have a
reproducibility of ~ 5μ and operate in roughing
vacuum to minimize air scatter and beam intensity degradation via absorption.
·
Fast monochromatic beam shutter with opening and closing times less than 20
msec, synchronized with the motion state of the
crystallographic spindle.
·
Precision crystallographic goniometer (using
the Kappa geometry), with remotely controlled X,Y
and Z spindle adjustments. The radius
of the sphere of confusion of the crystallographic axis will be less than
20μ. The
minimum stepping unit of the crystallographic scanning axis must be less than
1.75 x 10-5 rad. Maximum stepping rate
must be greater than 10o/sec to efficienty
support “Friedel Flipping” (inverse beam) data collection.
·
·
Ionization and sample fluorescence monitors.
·
Precision, remotely steered miniature beam stop.
·
Video microscope capable of visualizing crystals with edge lenths <10μ.
·
Multi-element fast CCD and detector positioner:
1. active area consisting
of at least 4000 x 4000 pixel elements with an effective pixel size less than
100x100 μ.
Phase I:
ADSC Q315: 6000x6000 pixels (315x315 mm active area)
Phase II,III: ADSC Q210
Phase IV:
ADSC Q315
2. aggregate
CCD array readout times less than 2 sec with high sensitivity and low noise.
3. maximum
spindle to detector distance (SDD)> 1m, minimum SDD < 0.1 m, with ability
to pitch detector about the 2θ axis (LR Desing A-frame).
·
High performance data flow and computational cluster.
This section describes mechanical and optical components of the Phase I
and II sector 24 ID beamlines from the front end
to the experimental endstations.. First, a comprehensive list of all optical,
mechanical and vacuum system components is presented, followed by a per item
description of principal optical components.
4.1 Component Listings.
Figure 4.1 and 4.2 consist of plan and elevation views, respectively of the layout for the Phase I (“passthrough”) beamline and layouts for hutches 24-ID-A, 24-ID-B and 24-ID-C. In this figure, hutch 24-ID-B is shown in the configuration prior to installation of Phase II optical components. Figure 4.3 shows a plan view of the phase II configuration of 24-ID-B and the phase II experimental enclosure 24-ID-E, after installation of the phase II optics. Appendix I contains all sector 24 layout drawings.
Table 2.1 sequentially
lists major optical or beamline components common
to build phases I and II and calls out their displacements from the center
of the sector straight. Table 2.2 lists
phase I-specific beamline components, while table
2.3 does the same for build phase II. Column 3 of Table 2.1 calls out drawing
number and provenance for said drawing or a vendor part number. Column 4 provides
a brief description of each component and indicates the source of the design.
All components indicated by an “M” designation are modified APS standard
components, with modifications imposed by NE-CAT. Principal optical component
descriptions are rendered in bold text in column 4.
Appendix 3
contains detailed assembly drawings for all principal optical components,
including masks, collimators, monochromators, focusing
mirror systems and shutters; except for those systems still under design.
Table 2.1:
Components common to Phase I and Phase II Optical Trains
| Item No. |
~Distance from Source (Meters) |
Component Drawing No. /Provenance |
Component Description S=APS STD M= Modified APS N=NEC V=Vendor |
| 1 |
24.4 |
410203013
/ APS |
Shield Wall Callimator
(S) |
| 2 |
25 |
3086102 |
100 l/sec Captor Ion Pump and stand |
| 3 |
25.6 |
4102030107
/APS |
Exit Mask Assembly (S) |
| 4 |
26 |
4102030111
/APS |
Be Window (S) |
| 5 |
26 |
4102030108
/APS |
Collimator Assembly (S) |
| 6 |
26 |
318020 |
Reducer, 20 l/sec Captor Ion Pump |
| 7 |
26.4 |
48236-CE44 |
Manually Actuated Gate Valve |
| 8 |
26.5 |
27600000-00
/NEC |
Pump, Mask Support Stand (M) |
| 9 |
26.5 |
|
Bellows (4.5” – 6” flange) |
| 10 |
26.7 |
|
4” Diam. 6” Flanges
Spool |
| 11 |
26.8 |
23-7000000
/NEC |
Cross, Titan
600 l/s Ion Pump (M) |
| 12 |
27.5 |
NE-100-01.doc /IDT |
Phase IV Power-Limiting Aperture (variable)
(V) |
| 13 |
27.7 -
32 |
|
4” Diam, 6” Flange
Spools, |
| 14 |
32 |
2860000000
/NEC |
Pump, Collimator Support Stand (S) |
| 15 |
32.3 |
NE-100-01.doc /IDT |
Phase I-Phase II Fixed Apertures (fixed)
(V) |
| 16 |
32.8 |
21-100000
/NEC |
Tungsten Bremsstrahlung Collimator
4, w. integral bellows. Two 9.5x9 (HxV)
mm bores (added since PDR submission). (M) |
| 17 |
33.2 |
23000100-00
/NEC |
Lead Collimator 5 45 x 15 (HxV) mm
bore. (M) |
| 18 |
33.6 |
23-600000
/NEC |
Cross, Titan 800 l/s Ion Pump (M) |
| 19 |
33.5 |
|
Bellows |
| 20 |
33.9 |
Series
10 /VAT |
Gate Valve, 8” flange |
| 21 |
34 |
|
8” Flange Spool, pump port, ion gauge port |
| 22 |
34 |
|
Downstream Wall of FOE (24-ID-A) |
| 23 |
34-46 |
ANL24IDWBT1001 /TECKNIT |
Coffin-style White Beam Transport 6” diam spools. (V) |
| 24 |
46.2 |
|
Upstream WALL of SOE (24-ID-B) |
| 20 |
46 |
|
8” Flange Spool, pump port, ion gauge port |
| 21 |
46.1 |
Series
10 /VAT |
Gate Valve, 8” flange. |
| 22 |
46.1 |
29600000
/NEC |
Pump, Mask Support Stand (M) |
| 22 |
46.2 |
|
Bellows |
| 23 |
46.5 |
23-600000
/NEC |
Cross, Titan 800 l/s Ion Pump. (M) |
| 24 |
47 |
NE-100-01.doc /IDT |
Phase II Power-Limiting Aperture (variable). (V) |
| 25 |
47.6 |
2160000
/NEC |
Tungsten Bremsstrahlung Collimator
6, w. integral bellows. Two 14x12
(HxV) mm bores (M) |
| 26 |
47.7 |
23000100
/NEC |
Lead Collimator 7 45 x 15
(HxV) mm bore. (M) |
| 27 |
48.2 |
/APS |
Water-cooled Phase II temporary White Beam Stop (S) |
| 28 |
48.1 |
|
Bellows |
| 29 |
48.2-50.2 |
|
6” Diam, 8” Flange
spools. |
| 30 |
50.2 |
Series
10 /VAT |
Gate Valve, 8” flanges. |
| 31 |
50.3 |
|
Bellows |
| 32 |
50.4 |
|
4” Diam 6-8” flange
spool |
| 33 |
50.3 |
26600000
/NEC |
Pump, Mask Support Stand (M) |
| 34 |
50.5 |
23-7000000
/NEC |
Cross, Titan
600 l/s Ion Pump (M) |
Table 2.2: Phase I (Passthrough)– specific optical components.
| Item No. |
~Distance from Source (Meters) |
Component Drawing No. /Provenance |
Component Description S=APS STD M= Modified APS N=NEC V=Vendor |
1 |
51.2 |
NE-100-01.doc /IDT |
Phase I Power-Limit Apertures (variable) Using working
apertures. (V) |
| 2 |
51.7 |
|
6” Diam, 8” flange spool. |
| 3 |
51.8 |
Series 10 /VAT |
Gate Valve,
6” flanges. |
| 4 |
52.2 |
110550-0001B GeneralA1 HLD-4_SPEC-V3.DOC /KOHZU |
Kohzu HLD-8-24 cryo-cooled monochromator. Si-111
crystals, 25 mm vertical offset. (V) |
| 5 |
52.8 |
HLD-3B /KOHZU |
Kohzu HLD-3B Beam Monitor. (V) |
| 6 |
53.1 |
/Oxford-Danfysik |
Oxford-Danfysik
split diode beam position monitor. (V) |
| 7 |
53.2 |
|
Bellows |
| 8 |
53.5 |
Series 10 /VAT |
Gate Valve,
6” flanges. |
| 9 |
53.5 |
27700000 /NEC |
P4-50 Support
Stand, 600 l/s Titan ion pump (S) |
| 10 |
54 |
23-200000 /APS |
P4-50 Integrated white beam stop, collimator and shutter. (S) |
| 11 |
54.5 |
|
Bellows
|
| 12 |
54.5-55.5 |
|
3” Diam, 6” Flange spool. |
| 13 |
54.8 |
|
Downstream wall of SOE (24-ID-B) - contiguous to upstream
wall of 24-ID-C. |
| 14 |
55.5 |
Series 10 /VAT |
Gate Valve,
6” flanges. |
| 15 |
55.6 |
|
Bellows. |
| 16 |
57 |
AHM2289 S0800 NE-CAT FDA.DOC /Oxford-Danfysik |
Oxford-Danfysik
Integrated Kirkpatrick-Baez focusing system. 1.2 m long
ULE HFM (4-point bender) 1.0 M long
ULE VFM (4-point bender) 2 600 l/s
Titan Ion Pumps. (V) |
| 17 |
58.8 |
|
Bellows |
| 18 |
59 |
Series 10 /VAT |
Gate Valve,
8” flanges. |
| 19 |
69-62 |
|
6” Diam, 8” Flange spools, w. 300 l/s Ion Pump |
| 20 |
62 |
Series 10 /VAT |
Gate Valve,
8” flanges. |
| 21 |
62 |
3603_aux_stand /LRD |
L-R Design
auxiliary support stand. (V) |
| 22 |
62.2 |
|
Be window. |
| 23 |
62.2 |
|
Bellows. |
| 24 |
62.3 |
JJ-SLITS.DWG /JJ-XRAY |
JJ-Xray
in vacuum X-Y Tungsten-blade slit system (V) |
| 25 |
62.5 |
UHV-QUAD.doc /Oxford-Danfysik |
Oxford-Danfysik
split diode beam position monitor. (V) |
| 26 |
62.7 |
PF2S2 PF4 |
XIA pneumatically actuated shutter
and attenuator assembly. (V) |
| 27 |
63.3 |
25000000 /NEC |
Extensible, evacuated collimator
assembly. (N) |
| 28 |
63.9 |
SL-TU-100-25 /ADC |
ADC in vacuum X-Y Tungsten-blade
slit system. (V) |
| 29 |
63.9 |
3604-053 /LRD |
L-R Design
Goniometer support stand + collimator alignment
system + LR-Design Kappa goniometer + L-R
Desing steerable beam stop. (V) |
| 30 |
65 |
3601Det-Support /LRD |
L-R Design
detector positioning system + ADSC Q315 multi-cell CCD detector system.
(V) |
Table 2.3:
Phase II (Single Side bounce)– specific optical components.
| Item No. |
~Distance from Source (Meters) |
Component Drawing No. /Provenance |
Component Description S=APS STD M= Modified
APS N=NEC V=Vendor |
| 1 |
51 |
NE-100-01.doc /IDT |
Phase II Power-Limit Apertures (variable). Using variable
apertures. (V) |
| 2 |
48.3 |
|
Bellows. |
| 3 |
48.5 |
E1107 Proposal.doc /Oxford-Danfysik |
Oxford-Danfysik
Single-crystal, side bounce mono-chromator. (V) |
| 4 |
49.4 |
Series 10 /VAT |
Gate Valve,
6” flanges. |
| 5 |
49.5 |
P4105090908 /APS |
P8 Shutter, 600 l/s Titan Ion Pump, Shutter support stand.
(S) |
| 6 |
50 |
|
Bellows |
| 7 |
50.76 |
/ |
Oxford-Danfysik
Horizontal focusing element of K-B
pair. 4-point bender, 1 m long
mirror. (V) |
| 8 |
51.1 |
|
Bellows |
| 9 |
51.1-53.4 |
|
2” Diameter
4” Flange Spool. |
| 10 |
54.4 |
/Oxford-Danfysik |
Oxford-Danfysik
Vertical focusing element of K-B
pair. 2-point bender, 1 m long
mirror. (V) |
| 11 |
55.2 |
|
Bellows |
| 12 |
55.2-57.4 |
|
6” Diam, 8” Flange spool. |
| 13 |
57.4 |
Seris 10 |
Vat Gate
Valve, 8” flanges. |
| 14 |
57.5 |
3603_aux_stand /LRD |
L-R Design
auxiliary support stand. (V) |
| 15 |
57.7 |
|
Be window. |
| 16 |
57.7 |
|
Bellows. |
| 17 |
57.8 |
JJ-SLITS.DWG /JJ-XRAY |
JJ-Xray
in vacuum X-Y Tungsten-blade slit system (V) |
| 18 |
58 |
UHV-QUAD.doc /Oxford-Danfysik |
Oxford-Danfysik
split diode beam position monitor. (V) |
| 19 |
58.2 |
PF2S2 PF4 |
XIA pneumatically actuated shutter
and attenuator assembly. (V) |
| 20 |
58.8 |
25000000 /NEC |
Extensible, evacuated collimator
assembly.(N) |
| 21 |
59.4 |
SL-TU-100-25 |
ADC in vacuum X-Y Tungsten-blade
slit system. (V) |
| 22 |
59.4 |
3604-053 |
L-R Design
Goniometer support stand + collimator alignment
system + LR-Design Kappa goniometer + L-R
Desing steerable beam stop. (V) |
| 23 |
60.5 |
3601Det-Support |
L-R Design
detector positioning system + ADSC Q315 multi-cell CCD detector system.
(V) |
4.3 Principal Component Descriptions
4.3.1 Common Optical Components
4.3.1.1 Instrumentation Design Technology LDT (IDT) Phase IV Power Limiting Aperture Mask
Assembly (non-standard).
The purpose of this component
is to limit the power deposited on the first crystal of the phase IV large
horizontal offset diamond monochromator, that will be installed in the first renewal phase of our
NIH funding approximately 3-4 years hence.
The design is conceptually similar to that of the APS L5-92 mask, modified
to accommodate two undulator beams with an angular
separation of 1mrad. Until the build phase IV monochromator
is installed this aperture will be locked in its most permissive geometry,
equivalent to a square aperture 4.5 x 4.5 mm.
The design rationale behind
all IDT apertures (Power-Liming (3 instances) and Fixed aperture (1 instance)
are discussed in detail under section 4.4.2 of this document. Appendix 3.10 contains both the design specification
and the results of finite element thermal simulations of the response of the
fixed-aperture IDT mask design to exposure to the tandem-undulator under normal and maximal beam mis-steering
conditions.
4.3.1.2 IDT Phase I and II Fixed Aperture Mask
Assembly (non-standard).
See discussion under 4.3.1.1
The principal purpose of
this element is to protect a tungsten bremsstrahlung
collimator located immediately downstream from this mask from overheating
by a mis-steered white undulator beam.
The design is functionally similar to an APS L5-92 mask, modified for
use in the context of the tandem undulator.
Conceptual Design of Fixed Aperture Mask.
4.3.1.3 Tungsten Bremsstrahlung Collimator 4
(modified-standard).
This collimator is the first
non-front-end associated bremsstrahlung collimator.
The design is a slight modification of a standard APS tungsten collimator
(APS K5-20). Instead of a single wide bore this collimator
has two bores 9.5 x 9 (h x v) mm, centered on the two undulator
beams. Bore size was determined by
the spread of the extremal synchrotron rays with sufficient leeway to provide a clearance
of at least 2 mm horizontal and vertical. This mask is protected from illumination by
the white beams by the fixed aperture mask (see 4.3.1.2). Drawings are provided in Appendix 3.11.
4.3.1.4 Lead Bremsstrahlung Collimator 5 (modified-standard).
This is a standard lead collimator
sized in the horizontal direction to comply with bremsstrahlung
shielding requirements. This collimator
is connected to the first tungsten collimator via a rotatable
flange. The tungsten collimator has
an intrinsic formed bellows to provide compliance at this flange join. The internal channel width and high of this
collimator is such than only the tungsten collimator is considered during
survey and alignment of this pair of collimators (via the kinematic
table surface adjustments). The fixed
a mask (4.3.1.2) has its own independent motorized translators for alignment.
4.3.2 Phase I – Specific Components
4.3.2.1 IDT Phase I Power Limiting Mask Assembly (non-standard).
See discussion under
4.3.1.1
This mask pair will be used
to limit the power load on the phase I monochromator. Both mask elements have one precision L-shaped
tungsten insert in its respective corner of the conjoint aperture formed by
the mask pair to minimize scatter from the aperture.
4.3.2.2 Kohzu HLD-8-24
Cryo-cooled Silicon Double Crystal Monochromator (standard).
The phase I monochromator is a modification of the standard Kohzu HLD-4 monochromator in operation
at COM-CAT and SGX-CAT. This is a vertically
offset monochromator with a built in video-based
beam position monitor (HKD-3.B), originally designed to operate with a pair
of water-cooled diamond crystals. The main modification from the HLD-4 design
is the inclusion of a liquid nitrogen bayonet-type rotational feed through
in addition to the normally available water feed-throughs
so that we can operate with a pair of liquid-nitrogen cooled silicon crystals.
The complete design specification of the HLD-8-24 and assembly drawings is
present in Appendix 3.1.
We will use the crystal and
crystal mount design used by APS sector 4 in its Kohzu
APM-5 monochromator (see Appendix 3.2, 3.3). The first crystal is a monolithic block with
a simple LN2 cooling channels and no undercut.
The second crystal passively cooled through an LN2-cooled OFHC block
and is long enough that no parallel translation of the crystal is required
to track the beam across its entire spectral range.
4.3.2.3 Oxford-Danfysik UHV Split-diode Beam
Position Monitor (non-standard).
Currently under design, this
device will allow determination of the monochromatic beam position to an accuracy
of 2-5 microns using the SBC-developed spit diode BPM installed in a UHV cross.
A rendering of the design is present in Appendix 3.5.
4.3.2.4 P4-50 Integrated White Beam Collimator Beam Stop (standard).
The Phase I photon shutter
is an APS standard P4-50 integrated collimator white beam stop, situated on
an APS standard support table.
4.3.2.5
The Phase I beam line will
use Kirkpatrick-Baez focusing. To conserve
longitudinal space in the experimental enclosure we have worked with Oxford-Danfysik
to develop and integrated support system for enclosing both the Horizontal
Focusing Mirror (HFM) and the Vertical Focusing Mirror (VFM) in a single vacuum
vessel, supported from a single vibration isolation platform
(Appendix 3.4, 3.5). We
hope that this design, in addition to conserving linear space will also provide
increased stability since both the HFM and VFM will be exposed to very similar
vibrational environment. Both mirrors are fabricated from
ULE, have rhodium, platinum and coating-free strips, and are clamped in 4-point
mirror benders (SESO). The HFM mirror
is situated upstream of the VFM and is 1.2 meters in length. The VFM is 1 m in length. Mirrors have the expected kinematic
positioning systems that also provide pitch and roll adjustments. All axes are associated with precision incremental
encoders. Additionally, a fast-response
piezoelectric actuator provided for rapid, fine adjustment of the pitch of
both mirrors.
The design specification
and assembly drawings of the phase I focusing system and shadow ray-casting
simulations of the focus spot
are attached in Appendix 3.6.
4.3.3 Phase II – Specific Components
4.3.3.1 IDT Phase II Power-Limiting Mask Assembly (non-standard).
See discussion under
4.3.1.1
This mask pair will be used
to limit the power load on the phase II monochromator. Both mask elements have one precision L-shaped
tungsten insert in its respective corner of the conjoint aperture formed by
the mask pair to minimize scatter from the aperture.
4.3.3.2 Oxford-Danfysik Cryo-Cooled
Single Crystal Side-Bounce Monochromator (non-standard).
The Phase II monochromator will consist of a liquid nitrogen-cooled Si
crystal (220) aligned to provide a fixed-energy beam (12.662 KeV) with a take-off angle of 29.59o. The Si crystal will
be mounted on a cooling plate along with another Si
crystal with a 311
cut, capable of providing a monochromatic beam at 14.78 KeV
along the same traverse as the first crystal.
Selection between the two crystals will be effected by a simple vertical
translation of the entire cooling block. The
second crystal will have independent fine pitch and roll adjustments.
We plan to use this configuration to
perform MAD data collection in the 2-energy mode, or monochromatic
data collection at the high or low energy.
Critical issues of the design include thermal stability of the crystal
stack and the practicality of fine steering of the low and high energy beams
over the same narrowly-defined traverse. We
are collaborating with Oxford-Danfysik to effect the design and construction of this monochromator, using subassemblies Oxford-Danfysik has used in prior designs.
The design specification
and model design renderings are presented in Appendices 3.7 and 3.8.
4.3.3.3 Phase II Permanent and Temporary Water-Cooled Beam Stop (non-standard).
A water-cooled white beam
stop will be situated on the main support stage of the Phase II monochromator to permanently stop residual pink beam. The beam stop will consist of an inclined block
(< 10o) block of glidcop with internal
joint-free copper water-cooling channels. Until the Phase II monochromator
is installed, the inboard-projecting undulator will
be administratively locked at maximum permissible gap. An additional safety margin will be provided
by installing a temporary water-cooled glidcop white
beam stop in a spool-piece attached downstream to lead collimator 7 (without
interference to the outboard undulator beam). The temporary stop will also block residual
radiation originating from the sector 24-dipole that enters the canted tandem
front end. The temporary phase II stop
will be designed by S. Sharma’s group.
4.3.3.4 P8 Monochromatic Shutter (standard).
The monochromatic Phase II
beam will be stopped using a standard APS P8 photon shutter, situated on a
shortened standard support table.
4.3.3.5 Oxford-Danfysik Horizontal Focusing Mirror
System (non-standard).
As with Phase I, Phase II
focusing will use the Kirkpatrick-Baez geometry. However, due to space limitations in the SOE
and 24-ID-E we cannot use the integrated solution used in Phase I, without
reverting to an undesirably high demagnification
geometry for the VFM.
We will instead, use a conventional
design that physically separates the VFM and HFM. The HFM will consists
of a 1.2 m long ULE pre-figured meridional cylinder
with rh, pt and bare strips, selectable by translation
of the kinematic mount. The mirror will be mechanically fine-figured
with a SESO 4 point bender.
4.3.3.6 Oxford-Danfysik Vertical Focusing Mirror
System (non-standard).
The VFM will be located immediately
next to the SOE – 24-ID-E partition and will us a 1 m long ULE mirror in a
2-point SESO bender. As with the Phase
I K-B system the Phase II K-B system will have peizo-electric
pitch adjusters for rapid-fine tune of both pitch axes.
The design specification
and assembly drawings of the phase II HFM and VFM and shadow ray-casting simulations
of the focus spot are
attached in Appendix 3.6.
4.3.4 Common Endstation Components
All elements of the sector
24 endstation design will recycle designs successfully
used in the construction and operation of NE-CAT beamline 8BM. All component
descriptions in this session are referents to a corresponding entry in an
Appendix providing detail drawings each component.
4.3.4.1 JJ-Xray in vacuum X-Y Tungsten slit blade
Assembly.
Appendix 3.13
4.3.4.2 Oxford-Danfysik in vacuum Split-diode
Beam Position Monitor.
Appendix 3.14
4.3.4.3 X-ray Instrumentation Associates pneumatically-actuated Shutter
and Beam Attenuator.
Appendix 3.15
4.3.4.4 Extensible, Evacuated Collimator Assembly.
Appendix 3.16
4.3.4.5 ADC in vacuum X-Y Tungsten Slit Blade Assembly.
Appendix 3.17
4.3.4.6 Miniature in-line Ion Gauge.
Appendix 3.18
4.3.4.7 LR-Design Steerable Beam Stop.
Appendix 3.19
4.3.4.8 LR-Design Goniometer Support, Kappa Goniostat.
Appendix 3.20
4.3.4.9 LR-Design A-Frame Detector Support System.
Appendix 3.21
4.3.4.10 Area Detector Systems Corp Q315/Q210
Multicell CCD Detector System.
Appendix 3.22
4.3.4.11 Console Distributed Control System; Data Flow Network
Appendix 4.1, 4.2
4.4 Phase I
and II Ray Tracing Diagrams.
All ray tracing figures accompanying this document have been revised relative
to those submitted in the NE-CAT PDR to reflect configuration changes in the
optics and the canted undulator front end design . We presume
two undulators of approximately 2.07 length, 3.3 cm periodicity, installed in our sector straight,
with a 1.0 mrad angular separation of the two undulator
beams. The front end configuration and general plan for ray projection are
taken from Y. Jasky’s anamorphic
drawings dated
Figures 4.4 and 4.5 show the horizontal and vertical bremsstrahlung radiation ray tracing. Figures 4.6 through
4.8 show the horizontal and vertical synchrotron ray tracing. Figures 4.10-4.12 show the diagrams for the
central synchrotron radiation rays for the monochromatic beam, indicating
the offset from the monochromator and the deflections
from the mirrors, and the location for the monochromatic beam stops.
4.4.1 Bremsstrahlung
Ray Tracing
Figures
4.4 and 4.5 show the horizontal and vertical bremsstrahlung
radiation ray tracing diagrams, respectively.
The principal purpose of the second tungsten bremsstrahlung
collimator (SOE)
is to limit the vertical extremal bremsstrahlung
rays permitted by the vertical bore of tungsten collimator 4 (see figure 4.6),
which would have passed through the vertical bore of lead collimator 7.
Fig. 4.4 Horizontal Bremsstrahlung Ray Tracing Diagram.
Fig. 4.5 Vertical Bremsstrahlung Ray Tracing Diagram.
Note
that a two channel water-cooled high-heat-load fixed copper mask (bore dimensions:
4.5 x 4.5 mm) is placed immediately upstream of the first bremsstrahlung (FOE) collimator to protect the interior bores
from possible beam mis-steering (see figures 4.6
- 4.8). Additional protection for the
two tungsten collimators is provided by the 2 sets of power-limiting apertures
on the in-board optical line. The bore
of the fixed copper mask and the geometry of the tungsten collimator bores
provide at least 2 mm clearance between the extremal synchrotron rays and the interior bores both tungsten
collimators. All collimators are mounted
on high load support tables with a kinematic surface plate. The surface plate incorporates precision jacks
and dove-tail slides for precise alignment of the tungsten mask bores relative
to the two undulator beam.s The large internal bores of the lead
collimators guarantee no interference with the alignment of the tungsten collimators.
All synchrotron masks are mounted on the same tables through motor-driven
translator stages with independent X,Y, pitch and
yaw adjustments. Thus, only the alignment of the tungsten collimators is involved
in setting the position of the surface
plate of the support tables.
Table 4.1 lists all bremsstrahlung
collimators (including front end components), their type, distance from the
center of the straight and parameters of the collimator bores. Table 4.2 tabulates the external dimensions
of non-front end bremsstrahlung collimators. Both
tungsten collimators are dual channel, and channel separation (bore center
to bore center) is listed in the 6th column of table 4.1. There
is an asymmetry in the horizontal bore dimension of the second tungsten collimator,
mandated by the minimum clearance between bore interior and the extremal synchrotron rays. Dimensions listed for the lead
collimators are those for the interior of the lead bore not the spool piece
bore (shielding aperture not optical aperture).
The optical aperture of the lead collimators is used in all ray trace
diagrams.
TABLE 4.1: Bremsstrahlung collimators: Aperture Geometry
| No. |
TYPE |
DISTANCE
FROM SOURCE
(m) |
HORIZONTAL
SIZE (mm) |
VERTICAL
SIZE (mm) |
APERTURE
SPACING (mm) |
| 1 |
Front End Horizontal Shielding Block |
19.5 |
46 |
NA |
NA |
| 2 |
Front End Wall Collimator |
23.6 |
56 |
26 |
NA |
| 3 |
Front End Exit Collimator |
25.7 |
40 |
8 |
25.8 |
| 4 |
Tungsten Dual Aperture |
32.7 |
9.5 |
9 |
32.9 |
| 5 |
Lead Single Bore |
33.0 |
48.4 |
18 |
NA |
| 6 |
Tungsten Dual Aperture |
47.4 |
11 (INBOARD) 13.5 (OUTBOARD) |
14 |
47.5 |
| 7 |
Lead Single Bore |
47.6 |
72.9 |
21 |
NA |
| No. |
TYPE |
DISTANCE
FROM SOURCE
(m) |
Width (mm) |
Height (mm) |
Length (mm) |
| 4 |
Tungsten Dual Aperture |
32.7 |
120 |
83 |
170 |
| 5 |
Lead Single Bore |
33.0 |
406 |
203 |
305 |
| 6 |
Tungsten Dual Aperture |
47.4 |
120 |
83 |
170 |
| 7 |
Lead Single Bore |
47.6 |
406 |
203 |
305 |
4.4.2 Synchrotron Radiation Ray Tracing
Figure 4.6 shows the horizontal synchrotron ray tracing for both phase I and phase II beamlines. The vertical synchrotron ray traces for phases
I and II are
shown separately in figures 4.7 and 4.8, respectively. The internal bores
of all collimating elements (lead and tungsten) are separated from the nearest
extremal synchrotron ray by at least 2 mm. All synchrotron masking is accomplished using
a similar dual channel mask design to be supplied by Instrument Design Technology
LDT (
Fig. 4.6 Horizonal Synchtrotron Ray Tracing Diagram.
Fig. 4.8
Vertical Synchrotron Ray Tracing Diagram, Phase II.
A fixed aperture mask consists of a pair of high-heat load collimating
elements installed in tandem in the optical train. Each collimating element of the pair is fabricated
from 200 mm long oxygen-free copper (OFHC) blocks with internal water cooling
channels and two bores: 1) a working bore 4.5 x 4.5 mm in size, centered on
one of the two undulator beams; 2) a large 20 x
20 mm “compliance” bore, centered on the opposing undulator beam. The opposite element of the pair has the same
configuration, but rotated about the central axis of the beamline by 180o. The working bore follows a 150
mm long lead-in taper with a 3o opening angle in order to keep
that maximum power density deposited on the OFHC block below 235 W/mm2
(maximum beam mis-steering). Both mask elements
are mounted on independent Y-Z precision translators. Mask pairs are interconnected via bellows with
an internal radius providing 13 mm of clearance relative to the beam. The
compliance bore permits unconstrained alignment of the working bore relative
to the beam it is intended to mask. The
fixed aperture bores are aligned so that both undulator
beams pass down the central channel of its respective working bore.
A power limiting mask has a similar configuration to the fixed aperture
mask pair, except that both working bores of the mask pair are aligned on
the same undulator beam.
An L-shaped tungsten blade is brazed into opposing corners of the mask
pair’s working bores. The two tungsten
blades are then translated along a diagonal connecting the two blades to independently
limit the Y and Z extent of the passed beam and thereby the power deposited
on downstream monochromatizing elements.
Each planned ID monochromator will have a power-limiting mask pair installed
immediately upstream of its position. Figure 4.9 presents the conceptual designs underlying
both mask types. Table 4.3 summarizes
the placement and the bore geometry of all synchrotron masks. In this table, the Distance from Source (column
2) is the distance from the straight center to the center of the bellows connecting
the mask pair.
IDT is currently finalizing designs for both the fixed and power-limiting
mask pairs. We have contracted with
them for a complete thermal analysis of the fixed-aperture mask using a preliminary
model design. This analysis, using
the performance characteristics of a full-length undulator A , operating at 100
mA ring current predicts a maximum temperature rise
of the OFHC mask block of less than 120oC under conditions of
maximal permitted beam mis-steering. Simulated
peak inner coolant wall temperature does not exceed 40oC, so local
coolant boiling should not be a concern. The Phase IV power limiter masks will be administratively
locked in its most permissive configuration until installation of the Phase
IV large offset transmission monochrmator. The Phase II and Phase I power limiters are placed
at positions where the maximum power density is a fraction of that the fixed
aperture is exposed to.
Since the canted tandem undulator produces approximately
80% of the power output of a conventional undulator
A and since the APS-sanctioned thermal
rise for OFHC is 150oC we should have sufficient operational “head-room”
to accommodate a planned 130-150 mA APS operational
modes. IDT’s
thermal simulation is presented in Appendix 3.10 of this report.
The Phase I optical train ends in the SOE with a standard P4-50 integrated
collimator- white-beam stop, centered on the outboard undulator beam at approximately 54 m front the straight center.
Prior to the installation of the Phase II single-side-bounce monochromator
a water-cooled inclined glidcop block will be installed
in a spool attached to the downstream flange of lead collimator 7 (48.2 m)
to specifically stop the inboard undulator white-beam.
This stop will be designed by Shusil Sharma
and fabricated locally and will be capable of tolerating the unattenuated
output of the inboard undulator with a temperature
rise < 150oC. The inboard undulator
(sourcing the Phase II optical train) will be administratively “locked” to
open gap until the Phase II monochromator and beam
line are installed. The Phase II single
crystal monochromator will incorporate a fixed water-cooled
white beam stop immediately downstream of the crystal goniometer. An APS
P-8 monochromatic shutter will be placed immediately after the Phase II monochromator on the monochromatic optical leg that diverges
from the undulator ray with a fixed take off angle
of 29.75 o (Si 220 tuned to the peak
of the selenium K-edge).
TABLE 4.3: Synchrotron radiation white beam collimators:
Locations
and Aperture Sizes
| COLLIMATOR DESIGNATION |
~DISTANCE
FROM SOURCE
(m) |
HORIZONTAL
SIZE (mm) |
VERTICAL
SIZE (mm) |
| Phase
IV Power
Limiter |
27.5 |
4.5 |
4.5 |
| Fixed Aperture |
32.3 |
4.5 |
4.5 |
| Phase
II Power
Limiter |
50.6 |
4.5 |
4.5 |
| Phase
II White
Stop |
48.2 |
STOP |
STOP |
| Phase
I Power
Limiter |
51.2 |
4.5 |
4.5 |
| Phase
I White
Stop h(P4-50) |
54 |
STOP |
STOP |