LU Fangjun(on behalf of the HXMT team)

Institute of High Energy Physics, Chinese Academy of Science

Current Status of

the Hard X-ray Modulation Telescope Project

Scienctific objectives

Introduction to the Payloads

Project status and schedule

Summary

Outline

The Hard X-ray Modulation Telescope project was proposed in 1993.

In the first proposal, HXMT contains 18 NaI/CsI phoswich scintillators with a total detection area of 5000cm2, aiming for a hard X-ray (20-250 keV) all-sky survey and pointed observations.

The mission was officially approved in March 2011.

1. Scientific objectives

Low energy X-ray telescope added

High energy X-ray telescopes only

< 2005 2005 2006 2010

Medium Energy X-ray Telescope added

Optimised for the working temperatures of the detectors

1. Scientific objectives

Evolution of the payloads onboard HXMT

Satellite Facts:Weight: ~2800 kgOrbit: 550 km, 43°Attitude: 3-Axis Stabilized precision 0.1 °Lifetime: 4 yearsObservation modes: Scan and pointing

1. Scientific objectives

HXMT collaborationInstitute of High Energy Physics (PI institute, payloads, scientific operation)Chinese Academy of Space Technology (satellite platform)National Space Science Center, CAS (space environment monitor, mission operation)Tsinghua University (participation in payloads and scientific operation)

Large sky-area scanDiffuse X-ray emission: cosmic X-ray background; X-ray

emission from the Galactic ridge and the Galactic center

regionDetection of new (transient) sources and constrain their

broad band (1-250 keV) propertiesFollow up observation of gravitational wave burstsPointed observationsX-ray binaries: multiwavelength temporal behaviors,

broad band spectra and Fe emission line

Equation of state in strong magnetic field: AXP, X-ray

Bursts

Monitoring of Blazars and bright AGNs

Sciences with HXMT

1. Scientific objectives

With the blocked, narrow, and broad FOVs, HXMT can subtract

the charged particle induced background and can estimate the

relative contributions of point source and diffuse background,

and can thus measure the diffuse X-ray emission in 1-250 keV.

The quality of the measurement is highly related to the in-orbit

particle background determination.

Diffuse X-ray background

(Türler et al. 2010, A&A 512, 49)

Blocked: only sensitive to local particle induced bkg

Broad: source + diffuse X-ray bkg+ local bkg

Narrow: source + diffuse X-ray bkg+ local bkg

Advantages of HXMT’s FOV

1. Scientific objectives

Detection of transient sources

Transient source

1. Scientific objectives

HXMT will do time resolved broadband spectroscopy for the brightest X-ray binaires.

Illustration of a black hole X-ray binaryBroad Fe-Kα line of XTE J165-500 byXMM-Newton pn (Credit: ESA/XMM-Newton)

Mission Spectral resolution (eV, @ 6keV)

Timing resolution(ms)

Energy coverage(keV)

Detection Area (cm2, @6keV)

Strongest sources without pileup(Crab)

HXMT 150 1 0.7-250 240 No limit

XMM-Newton (pn, timing mode)

150 0.03 0.5-10 800 0.085

Chandra (ACIS, cc mode) 150 2.7 0.5-8 300 0.02

RXTE 1200 0.006 2-250 6000 No limit

1. Scientific objectives

HE: NaI/CsI, 20-250 keV, 5000 cm2

Size ： 1900×1650×1000 mm

ME:Si-PIN

,5-30 keV, 952 cm2

LE:SCD,1-15 keV, 384 cm

2

Star tracker

2. Introduction to the payloads

HXMT/HE Components assembly• 18 main collimated phoswich detectors• 18 calibration detectors (automatic gain control)• 18 charged-particle anticoincidence plates (6 top +12 lateral side)• 3 particle monitors

The High Energy X-ray Telescope (HE)

2. Introduction to the payloads

The Medium Energy X-ray Telescope (ME)

ME uses 1728 Si-PIN detectors read out by 54 ASIC (application specified integrated circuit). The energy coverage of ME is 5-30 keV, and the total detection area is 952 cm2. The in-orbit working temperature of ME is -40 to -20 ℃

2. Introduction to the payloads

2×2CCD236

16 cm2

The low Energy X-ray Telescope (LE)

2. Introduction to the payloads

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 (@6 keV) . The total detection area is 384 cm2. The in-orbit working temperature is between -80 to -40 .℃

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.

2. Introduction to the payloads

HXMT/LE

HXMT/ME

HXMT/HENuSTAR

INTEGRAL/IBIS

RXTE/HEXTE

15

2. Introduction to the payloads

HXMT RXTE INTEGRAL/IBIS SWIFT NuSTAR

Energy Band (keV)

LE: 0.8-15ME: 5-30HE: 15-250

PCA: 2-60HEXTE: 15-250

15-10000 XRT: 0.5-10BAT: 10-150

3-79

Detection Area (cm2)

LE: 384ME: 950HE: 5000

PCA: 6000 HEXTE: 1600

2600 XRT: 110BAT: 5200

847 @ 9 keV60 @ 78 keV

Energy Resolution (eV)

150@ 6 keV2500@ 20 keV10000@60 keV

1200@6keV10000@60 keV

8000@ 100 keV

150 @ 6 keV3300 @ 60 keV

900 @ 60 keV

Time Resolution (ms)

LE: 1ME: 0.18HE: 0.012

PCA: 0.001HEXTE: 0.006

0.06 XRT: 0.14, 2.2,2500 BAT: 0.1

0.1

Sensitivity (@100keV, 3σ ，105s, mCrab)

0.5 1.5 3.8 9 0.03 @ 20 keV

Comparison between HXMT and other major hard X-ray telescopes

The Mechanical Model of the satellite was finished in 2012. The payloads and platform both passed the dynamical environment tests.The mechanical model of the satellite in

dynamical environment tests (2012.11)

Measureing the weight center and rotation inertia of the telescope

(2012.11)

3. Project status and schedule

The tests of the electric performance of the payloads were finished in Dec. 2012, and those of the whole satellite were finished in early March of 2013.

3. Project status and schedule

The electric model of HXMT’s payloads in assembling and testing (2012.12).

Vacuum thermal balance tests of the satellite were carried out in Dec, 2012. The quasi-qualification models of all the detectors joined the tests. Those of HE and LE worked well during the tests, but that of ME had some problems with the FPGA, which were fixed and tested early this year.

The payloads after thermal control coating

Some of the components jointed the vacuum tests

3. Project Status and schedule

October 22 ， 2013 19

3. Project status and schedule

All the space qualification models and the environmental tests were finished in 2013 and 2014.

• The electric fitting of the flight models of the payloads is almost finished.

• Environment tests started.• Calibration procedures fully tested for HE and LE,

and partly for ME.• The payloads will be delivered before the end of

November, and the expected launch date will be around September next year.

October 22 ， 2013 20

3. Project status and schedule

The ground calibration facilities

Finished in May 2014. The energy coverage of the monochromatic beam is 15~150 keV

HE calibration facility

Finished in the end of 2014. The energy coverage of the monochromatic beam is 0.8-30 keV.

ME 、 LE calibration facility

Comparison of the different sampling methods for calibration

The calibration results are consistent with each other. The 27 points sampling mode will be used.

27 points

192 points

22 annuli

The energy linearity and resolution of the HE main detector

How to deal with the “deviations” at the energy of the Iodide absorption line?

The detection efficiency of the HE main detector

The measured data and the simulation are not consistent especially in the low energy band. More factors such as the air absorption, moving of the beam position with energy need to be considered.

Preliminary calibration of LE

LE 正样探测器 C 机箱能量分辨率随温度变化的初步标定结果

Signal amplitude as a function of temperature for LE flight model

The calibration procedure of ME has also been tested.

• The electric fitting of the flight models of the payloads is almost finished.

• Environment tests started.• Calibration procedures fully tested for HE and LE,

and partly for ME.• The payloads will be delivered before the end of

November, and the expected launch date will be around September next year.

October 22 ， 2013 29

4. Summary

Thank you for your attention!

Backup materials

Detectors LE: SCD, 384 cm2;ME : Si-PIN, 952 cm2

HE : NaI/CsI, 5000 cm2

Energy Range LE: 1-15 keV;ME: 5-30 keV;HE: 20-250 keV

Time Resolution HE: 25μs; ME: 180μs;LE: 1ms

Working Temperature

HE: 18±1 ; ME: -50~-20 ; LE: -80-45℃ ℃ ℃

Energy Resolution LE: 2.5% @ 6 keV ME: 14% @ 17.8 keV HE: ≤16% @ 60 keV

Field of View of one module

LE: 6°×1.6°; 6°×4°; 60°×3°; blind;ME: 4°×1°; 4°×4°; blind;HE: 5.7°×1.1°; 5.7°×5.7° ； blind

Source Location <1' (20σ source)

Characteristics of the HXMT Mission

Orbit Altitude: ~550 km ; Inclination: ~43°

Attitude Three-axis stabilizedControl precision: ±0.1°Measurement accuracy: ±0.01°

Data Rate LE: 3 Mbps; ME: 3 Mbps; HE: 300 kbps

Payload Mass ~1000 kg

Nominal Lifetime 4 years

Working Mode Scan survey, small region scan, pointed observation

Total background of HE varying with time

Different background components of HE

Background components of ME Background components of LE

Simulation of the in-orbit background of HXMT

Short timescale varibility of black hole X-ray binaries up to 250 keV.

The hard X-ray detectors

RXTE/HEXTE 、 Suzaku/HXD and BeppoSAX/PDS

are too small (<1000 cm2) , and INTEGRAL/ibis and

SWIFT/BAT are of too high background to study the

short timescale hard X-ray varibilities of black hole

X-ray binaries. HXMT, with the large detecting area

(5000 cm2, 20-250 keV) and the relatively small field

of view (low background) , will provide unique

opportunity for studies in this field.

Variability amplitude as a function of energy for several black hole binaries. (Kaaret 2004)

Test the performance of the automatic gain control by changing the angle between the main detector and the geomagnetic field.

With out the gain control ， the amplitude variation of the same energy incident photons can reach 10.6% ， and it decreased to 0.243% using the AGC, the effect on the energy resolution is as small as 1.31% 。

Automatic Gain Control