1. The PFA focal plane camera
Jiang WeiChun (IHEP)
on behalf of the eXTP–PFA Consortium

2. OUTLINE Top Level Requirements PFA Focal Plan Design
PFA Assembly and Integration
PFA Calibration

3. OUTLINE Top Level Requirements PFA Focal Plan Design
PFA Assembly and Integration
PFA Calibration

4. PFA instrumental requirements
Item
Requirement
Goal
Energy range
2-10keV
Effective area（for 4 PFAs）
Energy resolution
Field of view (FWHM)
7.9 arcmin (limited by detector size)
Angular resolution
30 arcsec (HPD)
15 arcsec(HPD)
Point source localization
 TBC
  TBC
Time resolution
<500 μs
<100 μs
Dead time
Background
MDP (minimum detectable polarization)
<3%
<2%
Maximum source flux (steady, peak)
>0.5Crab, >5 Crab upto 24 houres
>1Crab, >20 Crab upto 12 houres

5. PFA functional requirements
Functions:
Focusing focal optics
Polarimetry focal plane camera
Timing focal plane camera
Spectrometry --focal plane camera
Operating modes:
Observation mode –normal working
Calibration mode –on-board calibration
Protection mode –shut down HV in SAA
Self-testing mode –ASIC self-test

6. OUTLINE Top Level Requirements PFA Focal Plan Design
PFA Assembly and Integration
PFA Calibration

7. PFA functional breakdown

8. PFA focal plane assembly performance
Item
Specifications
Detector size
1.2cm×1.2cm
Window
50μm Be
Working gas
 0.8atm(pure DME)
Efficiency
 See figure
Position resolution
80μm
Modulation factor
keV, see figure
System err
<1%
Energy range
2~10keV
Energy resolution
ASIC pixels
 105600
Relative time accuracy
≤10μs
Absolute time accuracy
50μs（TBC）
Dead time
≤500μs
Operating temperature
25±1℃(TBC)
Storage temperature
 -15℃~45℃(TBC)

9. Focal plane assembly functional design

10. Gas Pixel Detector (GPD)
Designed by the INFN-Pisa group (Bellazzini et al.)
Detecting Area:12mm×12mm
Pixel distance: 50μm,352×300 pixels
Noise level: 50e-

11. Imaging test of GPD
Gas: Pure
PSF:FWHM = 80 μm

12. GPD measurements of the polarized X-rays
Modulation Curve
Modulation factor
Consistent with simul.

13. The sensitivity limit (systematics)
Upper limit 0.8% (99% C.L.) or 0.6% (90% C.L.)
Without a P = π/2 component
With a P = π/2 component
χ2/dof = /97
χ2/dof = 85.0/95
DoM = 0.091%
DoM = 0.090%
99% DoM upper limit = 0.43%
μ = 0.54
99% DoP upper limit = 0.80%
90% upper limit is 0.6%

14. PFA filters wheel assembly performance
Item
Specifications
Positional accuracy
 1’
Hole number
5~6（TBC）
Motor lifetime
108 circles
X ray tube operating voltage (as needed)
10kV（TBC）
Polarized source number
1~2（TBC）
Unpolarized source number
2（TBC）

15. Filters wheel assembly functional design

16. Rotating mechanism
The rotating mechanism has flown on several past missions, the designing lifetime of the double coils stepper motor is 108 circles.

17. Filters wheel 1.Collimator to reduce the background,
2.Polyimide film to protect the GPD from micrometeoroid etc.,
3. Two kinds of unpolarized calibration sources,
4. Polarized source based on a radioactive source or a X ray tube?

18. X ray tube VS. radioactive source
Polarized source based on a radioactive source or a X ray tube?
X ray tube
Radioactive source
Advantage
More kinds of energy,
Can reach 100% polarization,
Can turn off the X ray
No need to deal with high voltage,
Easy to realize compact design.
Disadvantage
Need high voltage supply and control circuit,
Need to deal with high voltage safety, low pressure discharge etc.
Hard to reach 100% polarization,
Radioactivity
Polarized source based on Fe55
devised by IASF-Rome
X ray tube on ASTRO-H

19. The accelerator group at Tsinghua
Already produced very compact e-beam
Is thermal cathode possible?

20. PFA production tree

21. GPD with ceramic wing New: Original: 1.Mounted by ceramic wing
1.Mounted on PCB
2.Center of mass is high
New:
1.Mounted by ceramic wing
2.Mechanical property is improved

22. GPD of original design

23. GPD with ceramic wing

24. PFA preliminary design
CAD design for FPA
The dimensions is 200mm×200mm×155mm，the mass is about 6.5Kg。

25. FPA preliminary mechanics analysis results
Model analysis results:
1、The first-order natural frequency of components is 520Hz，which is the flexible cables local vibration。
2、There are several natural frequencies of electronics board from 590Hz to 910Hz。
Vibration analysis results
1、Input：15grms；
2、Max response：185grms；
3、Max response location：flexible cables；
4、Electronics board response：70-90grms；
5、Reference HXMT results，all the results are reasonable。

26. FPA preliminary thermal analysis results
Conditions:
ASIC: 0.5W,
Power modules: 0.75W×6,
Boundary:
Mounting surface of case is 20℃,
Surrounding is 20℃.
Temperature distribution of the inner shell of the ceramic spacer for GPD

27. One PFA budget PFA mass budget:
 Item
 mass(kg)
 FPA
 10
 FWA  4
PFA power budget (not including thermal control):
 Item
 power(W)
 FPA
 10
 FWA  1
PFA telemetry budget:
 source
generation rate (Mbps)
compressed rate (Mbps)
 PFA
crab
crab

28. OUTLINE Top Level Requirements PFA Focal Plan Design
PFA Assembly and Integration
PFA Calibration

29. AIT flow

30. Assembling for GPD

31. Integration of FPA

32. Integration of FWA

33. Focal plane assembly and filters wheel assembly

34. Focal plane assembly and filters wheel assembly

35. OUTLINE Top Level Requirements PFA Focal Plan Design
PFA Assembly and Integration
PFA Calibration

36. Preliminary PFA calibration requirements
Item
Requirement
Opportunity
Conditions
Energy range
2-10keV
FPA, FMA,
combined
Clean room, vacuum, normal temperature
Radioactive source, X ray tube, calibration beam line
Effective area（for 4 PFAs）
Energy resolution
Field of view (FWHM)
7.9 arcmin (limited by detector size)
vacuum, normal temperature
calibration beam line
Angular resolution
30 arcsec (HPD)
FMA,
Point source localization
 TBC

37. Preliminary PFA calibration requirements
Item
Requirement
Opportunity
Conditions
Time resolution
<500 μs
FPA
Clean room, normal temperature
Radioactive source, X ray tube
Dead time
Background
  TBC
No need
MDP (minimum detectable polarization)
<3%
FPA,
combined
Clean room, vacuum, normal temperature
Radioactive source, X ray tube, calibration beam line
Maximum source flux (steady, peak)
>0.5Crab, >5 Crab upto 24 houres

38. Summary PFA instrumental requirements is stated,
Focal plane camera consists of focal plane assembly(FPA) and filters wheel assembly(PWA),
The preliminary design of FPA and PWA is stated,
The preliminary thermal analysis results for FPA is shown,
The preliminary mechanics analysis results is shown,
Preliminary conception of AIT and calibration is stated.
Thanks!
Thanks！