TIPS Meeting
18 September 2003, 10am, Auditorium
1. COS: New Detector Work at SSL
Oswald Siegmund
2. The Status of the ST-ECF’s STIS
Calibration Lamp Project
Florian Kerber
Next TIPS Meeting will be held on 16 October 2003.
High performance microchannel
plate detectors for UV/visible
Astronomy
Dr. O.H.W. Siegmund
Space Sciences Laboratory, U.C. Berkeley
Work funded by NASA grants, NAG5-8667, NAG5-11547, NAG-9149
Space Sciences Lab, UC Berkeley, CA, USA
1
Advanced
Advanced MCP
MCP Sensors
Sensors for
for Astrophysics
Astrophysics
Existing
Existing Detectors
Detectors
High QE alkali halide cathodes (CsI, KBr) with ~50%QE covering 10nm - 185nm
MCP’s with 12µm to 6µm pores, background 0. 2 events cm-2 sec-1
Cross-delay line readouts with 15µm resolution, 90 x 20mm, 65mm formats
COS 2 x 90mm x 10mm XDL detector
GALEX 65mmsealed tube XDL detector
Space Sciences Lab, UC Berkeley, CA, USA
2
Advanced
Advanced MCP
MCP Sensors
Sensors for
for Astrophysics
Astrophysics
COS
COS FUV
FUV Detector
Detector and
and Electronics
Electronics
Space Sciences Lab, UC Berkeley, CA, USA
3
Advanced
Advanced MCP
MCP Sensors
Sensors for
for Astrophysics
Astrophysics
COS
COS FUV
FUV Detector
Detector QE
QE
CsI cathodes on FUV02 flight detector compared with COS spec
Segment B
Segment A
0.5
0.6
Requirements
QE post miniscrub2
Requirements
QE post miniscrub2
0.4
Quantum Efficiancy
Quantum Efficiency
0.5
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0
1100
1200
1300
1400
1500
1600
1700
0
1100
1800
WAVELENGTH (Å)
Space Sciences Lab, UC Berkeley, CA, USA
4
1200
1300
1400
1500
1600
WAVELENGTH (Å)
1700
1800
Advanced
Advanced MCP
MCP Sensors
Sensors for
for Astrophysics
Astrophysics
COS
COS Detector
Detector Event
Event Rate
Rate Performance
Performance
COS FUV local and global count rate performance
is better than FUSE, and exceeds specs.
Global count rate throughput
Gain and PHD vs. Localized Input Rate
(Single 25µm x 500µm Slit)
100000
2
80000
Relative Gain
Relative PH width
1.6
Relative Gain
Digital Event Counter (cps)
1.8
1.4
1.2
1
60000
40000
20000
0.8
0.6
0
0.1
1
10
100
Microchannel Pore Input Rate (cps)
Space Sciences Lab, UC Berkeley, CA, USA
0
50000
100000
150000
Fast Event Counter (cps)
5
200000
250000
Advanced
Advanced MCP
MCP Sensors
Sensors for
for Astrophysics
Astrophysics
COS
COS Detector
Detector Resolution
Resolution
COS detector co-added image of 10µm pinholes on 500µm centers & 25µm x 500µm
slits 200µm apart. Pixels are 6µm x 25µm or ~15,000 x 400 format per segment.
COS FUV01 Segment A - Pinhole Resolution vs. X
100
X FWHM(µm)
80
COS FUV detector resolution
is ~20µm x 30µm FWHM
60
40
20
0
0
2000
4000
6000
8000
10000
12000
14000
X centroid (pxl)
Space Sciences Lab, UC Berkeley, CA, USA
6
16000
Advanced
Advanced MCP
MCP Sensors
Sensors for
for Astrophysics
Astrophysics
Developing
Developing Detector
Detector Prospects
Prospects
Raw flat field image
Shows MCP multi
-fibers, but after
thermal correction
and division data
looks statistical (with
~4400 cnts/resel we
get S/N ~60:1).
Using FPSPLIT with 4 co-added images each with 60:1 S/N we get S/N of
~100:1 which is in close accord with photon statistics. For analysis see memo
by Wilkinson/Penton/Vallerga/McPhate.
Space Sciences Lab, UC Berkeley, CA, USA
7
Photocathode Development
GaAs Photocathodes on windows, & Diamond Photocathodes on Silicon & Si MCP’s
Polycrystalline boron doped diamond, band gap - 5.47 eV (227 nm) - Solar blind.
Hydrogenated diamond is air stable (<10% drop in 18 hours) and is very robust.
GaAs QE up to 50% in the red now possible, low background ≈10 events/sec @-20°C
Time response <1ns, for Interferometry, Lidar,Molecular fluorescence.
1
Diamond coated Silicon MCP
Cs activated
QDE
0.1
0.01
0.001
0
#2
#1
#5
#8
21201
Si MCP
20801
20501
Pre-hydrogenated values
500
1000
1500
2000
Wavelength (Å)
GaAs photocathode UV efficiency
Space Sciences Lab, UC Berkeley, CA, USA
Diamond Photocathodes on Silicon and Si MCP’s
8
GaN Photocathodes
0.6
60
Quantum Efficiency
Quantum Eficiency (%)
NIST CsTe diode
0.5
NW-BH071#3
NW-JG238#2
SVT3102#2
SVT2702S-52803
NW-JG238S#3
opaque
GALEX NUV01 CsTe
CsI #3 2/99 20°
0.4
0.3
0.2
50
40
30
20
10
0.1
semitransparent
0
1500
0
2000
2500
3000
3500
4000
150
4500
250
300
350
400
450
Wavelength (nm)
Wavelength (Å)
Fig.2. Measured QE of GaN samples on sapphire
(300µm) after cesiation, for semitransparent
(corrected for substrate transmission) & opaque modes
Fig.1. Measured quantum efficiency of CsI on MCP’s,
CsTe semitransparent (NIST) on MgF2 window and CsTe
semitransparent (GALEX) on thick UV silica windows.
Space Sciences Lab, UC Berkeley, CA, USA
200
9
Silicon MCP Developments
Silicon MCP’s
Hexagonal pore Si MCP with
~7µm pores, >75% open area
Silicon MCP’s are made by photo-lithographic methods
Photolithographic etch process - very uniform pore pattern
No multifiber boundaries & array distortions of glass MCP’s
Large substrate sizes (100mm) OK, with small pores (5µm)
High temperature tolerance - CVD and “hot” processes OK
UHV compatible, low background (No radioactivity)
Development in collaboration with Nanosciences.
Typical Silicon microchannel plates in test program
25mm diameter (75mm currently feasible)
40:1 to 60:1 L/D (>100:1 possible)
7µm pore size, hexagonal and square pore
~2° bias and 8° bias, resistances ~GΩ, to <100MΩ possible
Working on processing techniques to improve uniformity
Techniques for gain & QE enhancement under investigation
8cm Si MCP on
100mm substrate
Space Sciences Lab, UC Berkeley, CA, USA
10
Silicon MCP Performance Characteristics
Gain & PHD very similar to glass MCP’s, stacks of Si MCP’s (4) with gain up to 106
QE is similar to good bare glass MCP’s (COS, EUVE, 12/10/6µm)
The background rate is lower (0.02 events cm-2 sec-1) than any glass MCP
Gain and response uniformity are reasonably good. No “hex” modulation!
0.2
12/10µm COS
Si MCP
Bare glass
Si Hex MCP
0.15
QDE
6µm pore MCP
0.1
0.05
0
200
400
600
800
1000
1200
1400
Wavelength (Å)
QDE for Si & bare glass MCP’s vs Wavelength
Space Sciences Lab, UC Berkeley, CA, USA
Contrast enhanced image of the fixed pattern response
to a Hg vapor lamp with a stack of 4 Si MCP’s. ~14mm
area, 107 counts, ~50µm resolution XDL.
11
Cross strip anode readout
32mm x 32mm XS anode, 0.5mm period
Cross strip is a multi-layer cross finger layout.
Fingers have ~0.5mm period on ceramic.
Charge spread over 3-5 strips per axis,
Event position is derived from charge centroid.
centroid.
Can encode multiple simultaneous events.
Fast event propagation (few ns).
Anodes up to 32 x 32mm have been made
Signals are routed to anode backside by hermetic vias
Packaging can be compact with amp on anode backside
Overall processing speed should support >> MHz rates
Compact and robust (900°
(900°C).
Bottom fingers
Space Sciences Lab, UC Berkeley, CA, USA
12
Cross Strip Anode Electronics Chain
Basic encoding sequence
Small, low power ASIC encoding with sparsification
reduces data throughput requirements
Cross strip anode position encoding electronics
test-bed system. All signals amplified and
digitized. Can choose up to 12 bits per signal.
Space Sciences Lab, UC Berkeley, CA, USA
Anode backside showing the external
board where preamplifier chips are mounted.
13
Cross Strip Anode Readout
Outstanding Spatial Resolution/Linearity
~7µm pores are resolved, <3 µm electronic resolution with 10 bit encoding electronics
Image linearity is ~1µm level and shows pore misalignments and multi-fiber boundaries
Gain required is <4 x 105, allows higher local event rates than normal readouts
Lower gain means longer overall MCP lifetime due to reduced charge extraction.
Small zone of a single 12µm 160:1
L/D MCP at 2x105 gain showing
apparent displacement of pore images
at multifiber boundaries
Flood image of 12µm pore MCP pair at 4 x 106
Gain, ≈1mm square area.
Space Sciences Lab, UC Berkeley, CA, USA
14
Resolution
Resolution of
of Cross
Cross Strip
Strip MCP
MCP Sensors
Sensors
Gain 1.3 x 106
Air force mask on
6µm pore MCP pair
with cross strip readout
Space Sciences Lab, UC Berkeley, CA, USA
Air force mask on
Single 6µm pore
MCP optical image
15
Advanced
Advanced MCP
MCP Sensors
Sensors for
for Astrophysics
Astrophysics
GALEX
GALEX Early
Early Observations
Observations
60mm XDL detectors with CsI and CsTe photocathodes, Launched 6/03
M101
M83
Near-UV Channel
Space Sciences Lab, UC Berkeley, CA, USA
16
M51 – Whirlpool Galaxy
Comparison
GALEX Early Data
Ultraviolet
GALEX
Space Sciences Lab, UC Berkeley, CA, USA
Visible
DSS
17
Near Infrared
2MASS
M31 Andromeda
Space Sciences Lab, UC Berkeley, CA, USA
18
Spectral Characterization of
calibration lamps: STIS
An improved list of emission lines for
STIS Calibration Enhancement
Florian Kerber, ST-ECF
TIPS Meeting Sept 18th, 2003
2
Outline
•
•
•
•
•
Calibration lamps for HST spectrographs
STIS Calibration Enhancement (STIS-CE)
ST-ECF Lamp Project
Laboratory Work
Results and Outlook
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
3
Hollow cathode lamp
•
Schematic drawing
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
4
Pt/Ne hollow cathode lamp (IUE)
•
Parameters of operation
– starting voltage: 300 V; operating voltage: 185 V; current:
10 - 60 mA, power consumption: 2 W @ 10 mA
– dimensions: 19.7 by 4.5 cm; weight: 71 (285) g
•
•
•
•
Lifetime: > 750 h or 3 - 5 years of operation on IUE
Source brightness stability: ~ 5 % after 5 - 10 min
Rich emission line spectrum: 115 to 310 nm
Wavelengths for 585 lines; Shenstone (1939)
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
5
Hollow cathode lamps - HST (1990)
•
Goddard High Resolution Spectrograph (GHRS):
115 - 320 nm; Pt-Ne ok
•
Faint Object Spectrograph (FOS): 115 - 895 nm
– Addition of ~ 10% Cr to cathode extends coverage to 540
nm and Ne has lines up to 800 nm
•
Space Telescope Imaging Spectrograph (STIS): 115
- 1000 nm
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
6
Ready for Flight / Operations ?
•
Engineering
– for both Pt-Ne and Pt/Cr-Ne thorough characterization of
lamps in terms of hardware performance
•
Science Operations
– information on spectral output incomplete and crucial
wavelength information based on measurements done in
the 1930s (Pt) or absent (Cr)
– no spectral characterization of flight hardware
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
7
HST Spectrograph Operations
•
National Institute of Standards and Technology
– Pt-Ne lamp atlas 110 - 400 nm with ~ 3000 lines (Reader et
al., 1990, ApJS 72, 831)
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
8
STIS Operations
•
•
•
Pt line list from NIST
Cr lines can not be used because of lack of lab data
1st order long-slit modes have many Pt/Cr blends
– wavelengths assigned should be average weighted by line
intensity ratios, which are not known
•
Empirical approach using 2-D polynomial fits
for Echelle modes
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
9
STIS Calibration Enhancement
•
Physical Model of STIS
– Spectrograph Model
•
Laboratory Standards
– Good line list is required to realize full potential of
physical model
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
10
ST-ECF Lamp Project
•
•
•
•
•
Dedicated ESA funding
Measure spectrum of Pt/Cr-Ne lamp at NIST: 110 320 nm
Derive an accurate ( < 1/1000 nm) list of wavelengths
as input for STIS-CE
Quantify differences between Pt-Ne and Pt/Cr-Ne
spectrum
Look into aging effects of hollow cathode lamps
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
11
Status of the ST-ECF Lamp Project
•
•
•
•
•
•
•
First memorandum May 2001
Approved & funded in spring 2002
Contracts to NIST and IST (lamps) issued June 2002
FUV: 5 week measurement campaign Sep/Oct 2002
Intermediate results delivered Nov & Dec 2002
NUV: 6 week campaign in Apr/May 2003
Use within STIS-CE in progress
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
12
NIST Eagle vacuum spectrograph
•
10.7 m focal length, Vacuum UV (VUV) coverage
– 1.25 m/1 m diameter
– 13 m long, 15 m3
– 3 chambers
•
Two 16 in. UV sensitive photographic plates
– 750 Å coverage
– 0.78 Å/mm resolution
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
13
NIST Eagle vacuum spectrograph
14
Synchrotron UV Facility (SURF III)
•
Fourier Transform Spectrograph (FTS 700)
15
Hollow cathode lamp
16
ST-ECF Lamp Project - Status
•
Measure spectrum of Pt/Cr-Ne lamp at NIST
– 10.7 m vacuum spectrograph: 113 - 183 nm
– FTS: 165 - 350 nm Π
•
Π
Derive an accurate ( < 1/1000 nm) list of wavelengths
as input for STIS-CEs
– FUV: > 1100 lines total - 95% identified; 235 Cr
– NUV: > 3500 lines; ca 50% Cr in progress
F. Kerber, ST-ECF
Π
TIPS Sept 18th, 2003
17
ST-ECF Lamp Project - Status
•
Quantify differences between Pt-Ne and Pt/Cr-Ne
spectrum in progress
– addition of Cr changes of line ratios
– metal vs gas change as a function of operating current
•
Aging of lamps
– accelerated aging test: 30s on/30s off cycle
1000 h without significant change
– vintage flight hardware
FOS & GHRS lamps
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
18
Mystery feature “Clump” ~1430 Å
•
Seen in both in FOS and STIS
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
19
Chromium “Clump” ~1430 Å
Cr-Ne
Pt/Cr-Ne
Pt-Ne
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
20
FUV Spectra: Pt vs Cr
Pt-Ne: old & new
F. Kerber, ST-ECF
New Cr
Faint Pt-Ne: old
TIPS Sept 18th, 2003
21
NUV Spectra: Pt vs Cr
Pt/Cr-Ne
Cr-Ne
Pt-Ne
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
22
Input for STIS-CE
•
NUV λc: 2843 Å
•
Lines seen : ~ 450
Pt: ~ 100 lines
Cr: ~ 700 lines
known
•
•
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
23
Open Instrument Surgery
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
24
Veteran Space Lamps
•
After seven years
of operation in
space back to the
lab ...
FOS
GHRS
they still work
perfectly fine
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
25
ST-ECF Lamp Project: Future
•
•
•
•
•
•
NUV FTS data reduction, fall 2003
Return of FOS lamps to museum, Sept 23rd
Paper I, ApJS, Sept 2003 (FUV results)
STIS-CE new dispersion solutions, end 2003
Incorporate into calstis pipeline
STIS calibration proposal #10031 (PI: B. Mobasher)
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
26
Lessons learned: Calibration ...
•
requires attention to detail …
•
requires expertise from different fields
•
will give you better results
•
is at the heart of scientific understanding
needs to be an integral part of any science project
F. Kerber, ST-ECF
TIPS Sept 18th, 2003
27
Lessons learned ...