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HYSPECHYSPEC
HYSPEC INSTRUMENT DESIGN – OUTLINE The two “models” considered for HYSPEC – inside & outside (Mark)
A breakdown of the components of the two models (Mark)
Estimates of the cost (Mark)
COFFEE BREAK
Simulating the two models (Vinita) - MCNP considerations for shielding drum & T0 chopper - McStas flux at sample considerations
Engineering the drum shield & the detector vessel (Bill) - Available angular ranges
Polarization analyzer system (Igor)
HYSPECHYSPEC
The Generic Layout of HYSPEC
T1A chopper
T1B chopper
Drum shield
HYSPECHYSPEC
Model one: BL14B, 25m from moderator (inside hall)
• Straight guide 4cm(w) x 15cm(h)• 4.5m sample to detector
HYSPECHYSPEC
Model two: BL14B, ~37m from moderator (outside hall)
• Curved guide 4cm(w) x 15cm(h)• 4.5m sample to detector• (6m sample to detector)
HYSPECHYSPEC
HYSPEC is a time of flight spectrometer
Measure on a surface in (Q,E) space
“Interrogate” (Q,E) space by moving the surface around
Needs high intensity to sample many (Q,E) surfaces
(160 detectors – 20 x 8-pack of LPSD’s)
HYSPECHYSPEC
HYSPEC is :-
high intensity (hence focusing mono)
medium resolution ΔE/E ~ 5%
“thermal” energy range ~5 < E < ~100meV
[G. Granroth & D. Abernathy, ICANS-XVI]
HYSPECHYSPEC
I
MC
2C
2M
MC
2C
2M
I
I
I
I EL 1142
t
T
t2
T
T2
E
E
F
21
2C
2M
2
MC
CS
SD
C
F
S
F
F Et
1L
L1
L 1142
t
T
T2
E
E
I
MCMC
E
L2284T
F
SDF
E
L2284T
LMC
LCS
LSD
Moderator
Disk choppers
Focusing crystals
Sample
Detectors
τM
ΔtC
Resolution (qualitative – not M.C.)
Spreading of pulse from chopper to sample
Secondary resolution governed by ratio of burst time ΔtC to distance LSD
Secondary spectrometer
Primary spectrometer
Low EI – τM dominates High EI – ΔtC dominates
τM – source (moderator) pulse width for EI
ΔtC – burst time for disk choppers
HYSPECHYSPEC
3F2
C
2M
2
MC
CS
2
SD
C3I2
MC
2C
2M
2F
2I
E t
1L
L1
L
tE
L
t
1142
1
EEE
Dashed lines:
Inside: LMC=25m, LCS=2.45m, LSD=4.5m, ΔtC=50μs
Solid lines:
Outside: LMC=37m, LCS=3.20m, LSD=4.5m, ΔtC=50μs
HYSPECHYSPEC
T0 chopper
Frame overlap chopper (T1a)
m=3 guide
Order suppressor chopper (T1b)
Counter rotating diskchoppers (T2)
Drum shield
Focusing crystals(Focusing “monochromator”)
Sample stage + floor
Detector vessel
INSIDE OUTSIDE
HYSPECHYSPEC
T0 chopper
Located just outside SNS biological shield at ~6.3m
Remove (reduce) fast neutron (MeV, keV, eV) flux
Horizontal axis rotors – 20cm of Inconel running at 60 (or 30) Hz
Inside: 2 counter rotating choppers - Total of 40cm of Inconel - Straight view of moderator - Drum shield thickness
Outside: 1 chopper - Effect of curved guide - Out of line of sight - Drum shield material/size
Both cases: reduce nos. of windows - Would like (want) to integrate vacuum with guide & frame overlap chopper
HYSPECHYSPEC
Frame overlap chopper
Just after the T0 chopper (both inside & outside)
Even @ 25m (inside) frame overlap on a “cold” source is a problem
60Hz disk chopper
B-loaded so that we can remove “hot” as well as cold neutrons if required
Integrated vacuum with guide & T0 chopper (windowless)
T
X
LC
LF
HYSPECHYSPEC
T
X
LC
LF
T
X
LC
LF
Measuring in the same frame
Measuring in the next frame
HYSPECHYSPEC
m=3 Guide
G1 G2 G3 Mono
Source
G5 Soller or Fermi chopper
Sample
Sample
G4
4m 2m 0.41m
2.3m 0.5m 0.1m 0.03m
0.22m
1.05m
0.2m
Distances and dimensions Source: 0.10m (w) x 0.12m (h) G1: tapered guide 0.12m (h) to 0.15m (h), 0.04m (w) G2, G3, G4: straight guide 0.15m (h), 0.04m (w) Mono: focusing HOPG(002) 0.3m (w) x 0.2m (h) G5: tapered guide 0.2m (h) to 0.1m (h), 0.04m (w) Mono to sample distance: 1.8m Sample area: 0.02m (h) x 0.02m (w)
(L1 - 9.56)m
Inside: straight guide
Outside: curve to get out of line of sight followed by 4m straight
HYSPECHYSPEC
T0 chopper
Frame overlap chopper (T1a)
m=3 guide
Order suppressor chopper (T1b)
Counter rotating diskchoppers (T2)
Drum shield
Focusing crystals(Focusing “monochromator”)
Sample stage + floor
Detector vessel
INSIDE OUTSIDE
HYSPECHYSPEC
Counter-rotating disk choppers
Disks at 300Hz (ΔTC~50μs)
Diameter ~ 700mm
Gd coated
Want to integrate vacuum with guide
Picture above has external motors
Picture left has internal motors
HYSPECHYSPEC
Order suppressor chopper
Counter rotating disk chopper @ 300Hz
Opens 5 times per frame
Need to block 4 out of 5 “pulses”
Order suppressor chopper @ 60Hz
B-loaded disk chopper (as for frame overlap & other SNS disk choppers)
Integrated vacuum with guide & other choppers (windowless)
Example: Counter rotating pair @ 300Hz, LMC=25m
E0 1 2 3 4 T(E) T(E)-frame 1 2 3 43.60 366396 278 71 32 30094 13428 94 3428 6761 100945.00 22 14 672 106 25536 8869 12203 15536 2203 5536
10.00 146 50 25 15 18057 1390 4723 8057 11390 1472315.00 1640 145 50 25 14743 14743 1410 4743 8076 1141030.00 17 18053 231 65 10425 10425 13758 425 3758 709245.00 23 14 958 122 8512 8512 11845 15179 1845 517960.00 28 17 6562 200 7372 7372 10705 14038 705 403890.00 37 20 13 452 6019 6019 9352 12686 16019 2686
HYSPECHYSPEC
Focusing (monochromator) crystals
Non-polarizing – HOPG(002) Polarizing – Heusler(111)
[Picture is of double focusing mono for MACS at NIST]
[Picture is of “double” focusing Heusler mono for IN20 at ILL]
HYSPECHYSPEC
“Monochromator” drum shield
Needs to “stop” the beam
Inside – direct view of source, needs to be more substantial. I.D. ~ 0.4m, O.D. ~ 2.8m
Outside – curved guide, out of line of sight, can be smaller. I.D. ~ 0.6m, O.D. ~ 1.8M
Using HFIR drum (see right) as a starting point.
HYSPECHYSPEC
T0 chopper
Frame overlap chopper (T1a)
m=3 guide
Order suppressor chopper (T1b)
Counter rotating diskchoppers (T2)
Drum shield
Focusing crystals(Focusing “monochromator”)
Sample stage + floor
Detector vessel
INSIDE OUTSIDE
HYSPECHYSPEC
Relationship: disk choppers & drum shield
INSIDE OUTSIDE
Disk choppers
Inside: choppers must be inside drum shield
Outside: - drum shield is smaller (larger I.D., smaller O.D) - choppers can be further from sample for same resolution
F2C
2M
2
MC
CS
SD
C
F
S
F
F Et
1L
L1
L 1142
t
T
T2
E
E2
1
HYSPECHYSPEC
HYSPECHYSPEC
T0 chopper
Frame overlap chopper (T1a)
m=3 guide
Order suppressor chopper (T1b)
Counter rotating diskchoppers (T2)
Drum shield
Focusing crystals(Focusing “monochromator”)
Sample stage + floor
Detector vessel
INSIDE OUTSIDE
HYSPECHYSPEC
Fermi chopper – high resolution mode
3F2
C
2M
2
MC
CS
2
SD
C3I2
MC
2C
2M
2F
2I
E t
1L
L1
L
tE
L
t
1142
1
EEE
LSD
Moderator
Disk choppers
Focusing crystals
Sample
Detectors
C a vitie s fille d withne utro n a b so rb e r
Bo tto m p la te
Slit p a c ka g e
To p p la te
Sha ft
Drive m o to r
Slit p a c ka g efra m e
100 m m
84.5
mm
48 .5 mm
59.0
mm
Stra ig ht c ha nne l Fe rm i c ho p p e r
HYSPECHYSPEC
T0 chopper
Frame overlap chopper (T1a)
m=3 guide
Order suppressor chopper (T1b)
Counter rotating diskchoppers (T2)
Drum shield
Focusing crystals(Focusing “monochromator”)
Sample stage + floor
Detector vessel
INSIDE OUTSIDE
HYSPECHYSPEC
Sample stage – dance floor & airpads
[ Picture is IN20 triple axis spectrometer at the ILL, Grenoble ]
o Sample stage
o Dance floor (granite tiles)
o Airpads
HYSPECHYSPEC
Detector vessel
Angular range: 60° (horz), 15° (vert)Sample detector dist: 4.5m, (6m)
Detectors: 20x 8-pack LPSD’s (1.2m long for LSD=4.5m) “Copies” of ARCS/SEQUOIA
Atmosphere: Argon (LPSD’s won’t work in He)
Electronics/DAE: As per ARCS/SEQUOIA
Front window: Permanent “rough” collim inside the detector
Outside vessel: Radial collimator (remove SE scattering) Polarization analyzers
HYSPECHYSPECPRELIMINARY COST ESTIMATES INSIDE (k$) OUTSIDE (k$)
Core vessel insert 127 127 Shutter insert 169 169 Primary spectrometer T0 chopper 638 356 Frame overlap chopper 188 188 Primary guide and shielding Guide 515 824 Guide support 217 347 Shielding 1049 1678 Monochromating system Chopper system 834 834 Focusing crystals 854 854 Housing/shielding 1900 1100 Mono system to sample arm Optics 32 32 Mechanical connection 300 300 Tertiary shutter 20 20 Secondary spectrometer Sample stage Sample goniometer/rotation 62 62 Detector vessel (LSD=4.5m) Vessel 485 485 Shielding 292 292 Optical components Radial collimator 50 50 Polarization bender analyzer 1223 1223 Detectors/DAE LPSD’s 365 365 DAE 120 120 Sample & detector motion Granite floor 177 177 Airpad system 40 40 Spectrometer housing External building 1700 Enclosure/hutch 200 Instrument control Hardware 22 22 Software Intg. Des. & System Int. Scientist, Engineer, Travel 1200 1200 Not yet calculated Software, 2nd shutter, argon handling, vacuum, addl. int. des. 500 500
ESTIMATED TOTAL (excl. contingency & escalation) in 2004 dollars 11600 13100