1. Overview of the Low Energy Telescope and its Performance in-orbit
Prof. Yong CHEN
Key Laboratory of Astronomical Physics
11th. Apr. 2018

2. Outline
Introduction to LE
Calibration on Ground
Performance in-orbit

3. Introduction to HXMT Star tracker ME:Si-PIN,5-30 keV, 952 cm2
LE:SCD,1-15 keV, 384 cm2
Size：1900×1650×1000 mm
HE: NaI/CsI, keV, cm2

4. The low Energy X-ray Telescope
LE consists of 3 detector boxes, and each boxes contains 32 CCD 236 chips, which have a time resolution of 1ms and energy resolution of <140 eV keV) . The total detection area is 384 cm2. The in-orbit working temperature is between -80 to -40 ℃.
Heat pipes
Light Shield
POS Collimator
ASM
Collimator
DAQ
Box

5. The low Energy X-ray Telescope
Electric Control Box
Data Acquisition Box

6. Swept Charge Devices
SCD

7. Important Parameters Detection Area 384 cm2 Detection Range 0.7-15 keV
Field of View
1.6×6
4×6
50~60 × 2~6
Closed
Energy Resolution
keV
Time Resolution
~1 ms
Detector Operating Temperature
-80℃ ~ -30℃
diagonal [daɪˈægənl]
vertical
horizontal

8. Sensitivities
HXMT/LE
INTEGRAL/IBIS
HXMT/ME
RXTE/HEXTE
HXMT/HE
NuSTAR
The sensitivities of the three telescopes of HXMT. The sensitivities of NuSTAR, INTEGRAL/IBIS and RXTE/HEXTE were reprinted from Koglin et al. (2005)3.

9. Sensitivities
XMM-Newton

10. Work mode
Trigger Mode：Forced Trigger & Trigger over the threshold
Readout Mode： Continuous Readout & Long Exposure
Readout Frequency：100kHz & 50kHz

11. Performance On Ground
Detector Box 1

12. The Merged Spectrum of Box 1
Energy Resolution
The Merged Spectrum of Box 1

13. E-C Calibration Spectrum of Mg-k Spectrum of Al-k Spectrum of Mo-L
magnesium [mægˈni:ziəm] aluminum molybdenum [məˈlɪbdənəm] Argentine ['ɑ:dʒəntaɪn]
Spectrum of Mo-L
Spectrum of Ag-L

14. E-C Calibration Spectrum of Ti-K Spectrum of Cr-K Spectrum of Fe-K
cobalt [ˈkəʊbɔ:lt]
Spectrum of Fe-K
Spectrum of Cu-K

15. The Integral Non Linear of the Detector
E-C Calibration
The Integral Non Linear of the Detector

16. FWHM vs Incoming X-ray Energy
E-C Calibration
FWHM vs Incoming X-ray Energy

17. Vacuum Test of HXMT-LE Flight Module
chlorine [ˈklɔ:ri:n] magnesium [mægˈni:ziəm] calcium [ˈkælsiəm] molybdenum [məˈlɪbdənəm] Argentine ['ɑ:dʒəntaɪn]
manganese [ˈmæŋgəni:z] cobalt [ˈkəʊbɔ:lt] nickel [ˈnɪkl] zinc [zɪŋk]
A Spectrum in the Thermal Test of the HXMT Flight Module

18. Relative QE Calibration
The EBIT (Electron Beam Ion Trap) equipment can generate the Gas Plasma, which is almost the same as the environment of the HXMT orbit.
The relative detection efficiency of SCD detectors has been calibrated by the EBIT (Electron Beam Ion Trap) equipment in Fudan University, where a HPGe (High-Purity Germanium) detector is used as a standard detector monitoring the X-ray flux.

19. Relative QE Calibration
The Spectra Comparison between the -100℃ and liquid Nitrogen detector

20. Relative QE Calibration
Comparison between the Theoretical and the Experimental Detection Efficiency

21. Absolute QE Calibration
Using Fe-55.
Replacing CCD236 with SDD.
Small hole at the entrance of the source to ensure the spot within the sensitive area of both detectors.

22. Absolute QE Calibration
Absolute QE can be determined with the comparison with SDD and CCD236.
The thickness of depletion layer can be also calculated.

23. Vacuum Test of HXMT-LE Flight Module
Time fold
Time Response in Long Exposure Mode

24. Generation of LE RMF Raw Spectrum Panning
The RMF of single events in -70℃
Interpolation

25. Background Calibration
The calibration is carried out in CJPL.
CJPL has covered with rocks of a thickness of 2400m, which is the thickest all over the world.

26. Background Calibration
The count rate of one CCD module is ~0.016cts/s.

27. Noise Comparison

28. Launch of Insight-HXMT
The Insight-HXMT has been launched in 15 Jun
After nearly 4 months on-orbit calibration, she is going to deliver to users.

29. Scorpio X-1
700 eV
Preliminary results

30. Cas A
700 eV
Preliminary results

31. Response to the Crab Pulsar
Blue stands for LE, Green stands for ME,

32. Performance in-orbit Box 1 Box 2 Box 3 On Ground In-Orbit Box 1
On Ground
In-Orbit
Box 1
189.4 keV
192.1 keV
Box 2
147.1 keV
148.1 keV
Box 3
157.6 keV
165.3 keV

33. Summary Energy range of LE is 0.7－15keV
Time Response is fast with less pile-ups
4 kinds of the collimators
Be able to accomplish the pointing observation , survey and all sky monitor,
Energy resolution is ab. -70℃
All performance meet the design targets
Manage to pass all the tests before launching
Work well in-orbit