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

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

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

PFA instrumental requirements Item Requirement Goal Energy range 2-10keV Effective area（for 4 PFAs） 400cm2@2keV 500cm2@2keV Energy resolution 1.8keV@6keV 1.5keV@6keV 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 <10%@1Crab <3%@1Crab 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

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

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

PFA functional breakdown

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 μ=0.59@6 keV, see figure System err <1% Energy range 2~10keV Energy resolution 20%@6keV 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)

Focal plane assembly functional design

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-

Imaging test of GPD Gas: Pure DME @0.8atm PSF:FWHM = 80 μm

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

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 = 118.93/97 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%

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）

Filters wheel assembly functional design

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

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?

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

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

PFA production tree

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

GPD of original design

GPD with ceramic wing

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

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。

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

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  1.4@1 crab  0.7@1 crab

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

AIT flow

Assembling for GPD

Integration of FPA

Integration of FWA

Focal plane assembly and filters wheel assembly

Focal plane assembly and filters wheel assembly

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

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） 400cm2@2keV Energy resolution 1.8keV@6keV 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

Preliminary PFA calibration requirements Item Requirement Opportunity Conditions Time resolution <500 μs FPA Clean room, normal temperature Radioactive source, X ray tube Dead time <10%@1Crab 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

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！