1. THE FAST X-RAY MONITOR (FXM) BASED ON YAP:CE SCINTILLATOR (YTTRIUM ALUMINUM PEROVSKITE ACTIVATED BY CERIUM) FOR THE “CORONAS-PHOTON” SATELLITE PROJECT E. Fedorovykh Astrophysics Institute at Moscow Engineering-Physics Institute, RUSSIA

2. Instrument FXM Goals of experiments: Fast monitoring of hard X-ray Solar radiation in the energy range of 20 – 600 keV with 2 – 3 ms time resolution; Registration of Solar flare X-ray radiation temporal profile in 6 differential and 2 integral energy sub-bands.

3. FXM block-diagram Instrument FXM consists of: detection block FXM-D, high-voltage source block HVS-5, electronic block FXM-EM. Blocks FXM-D, HVS-5 are installed on an extendable platform. Block FXM-EM is installed in a pressure compartment.

4. Detection block FXM-D FXM-D onboard “CORONAS-PHOTON” Overall dimensions 366x204x122 mm, Weight 5 kg.

5. Detection block FXM-D Collimator (field of view 6°) Scintillator YAP:Ce Light-emitting diode board PMT Divider Discriminator block Stabilization block Preamplifier 10mm Ø70mm

6. Properties of YAP:Ce Thickness of crystal 10 mm YAP:Ce – yttrium aluminum perovskite with cerium, YAlO 3 (Ce) YAP:CeNaI(Tl) Decay time, ns27250 Density, g/cm 3 5,553,67 Hygroscopicnovery Relative light output 40100 Wavelength of emission max., nm 350415

7. Energy spectra of YAP:Ce Channel Counts Channel Counts Energy spectrum of the radioactive source Am 241. The crystal thickness was 10 mm. Energy spectrum of the radioactive source Cs 137. The crystal thickness was 10 mm.

8. Detection block FXM-D Stabilization block The measurement channel is stabilized using precise impulses from the light source (light- emitting diode) placed in the collimator in front of the crystal. The system stabilization reaction time is 0,1 s. This system controls the PMT power supply. This helps one to avoid the influence of output characteristics at high count rate. Discriminator block Signals from preamplifier separated according to their amplitude into six differential channels. Two integral channel are provided too. Channel numberEnergy channel, keV 120-30 230-40 340-50 450-70 570-130 6130-600 720-600 8>600 100 ns 500 mV Output waveform Rise time 38 ns Fall time 116 ns

9. High voltage source block HVS-5 Overall dimensions 225x190x57 mm, Weight 2 kg. Block HVS-5 is adjustable high voltage source with range from 900 V to 1900 V. Controlling is realized by external control signal 0 - 10 V, generated in the stabilization block.

10. Electronic block FXM-EM Block FXM-EM realize following functions: low voltage supply to FXM-D and HVS-5 blocks; change of data acquisition time interval (temporal resolution) by means of control code words (UKS); counting of events in FXM-D channels, recording to data frames and transfer to the Scientific data acquisition and registration system (SSRNI).

11. Conclusion At present FXM has passed almost all preflight tests. Flight model is under making now. FXM Web-page: http://iaf.mephi.ru/coronas-photon_brm.htm