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