1. Research progress of 7mm receiver amplitude calibration
Kai WANG

2. What is amplitude calibration？

3. Centimeter band calibration
Vhot,Vcold,Thot,Tcold → Tcal → Tsys → TA → Sv

4. Noise Diode Estimates
Determining Tcal from hot-cold load measurements in the lab
Observers can’t do there own Hot-Cold tests
Provide 10-15% accuracy
Time consuming
Recommend an On-Off observation Sv → Tcal

5. Millimeter band calibration
Vhot,Vcold,Thot,Tcold → Tcal → Tsys → TA → TA* → Sv

6. Chopper wheel calibration
BTL(Bell Telephone Laboratory )

7. Uncertainties of mm band calibration
10% accuracy have been the ‘standard’
Usually, errors in Air Mass, Opacity, Aperture efficiency, Tcal

8. Airmass estimate Airmass traditionally modeled as 1/sin(Elev)
For 1% calibration accuracy, must use a better model below 15 deg.
For 1% calibration error, require A to ~0.1

9. Opacity estimate
Vertical weather data provides absorption as a function of height(Temperature, Pressure, Dew Point, Cloud Cover, …)
For 1% calibration accuracy, requires opacity to 0.01

10. Opacity estimate Must do multiple tips for wideband observations
Tips take up telescope time
Requires knowing Tcal to high accuracy

11. Telescope efficiencies

12. Tcal estimate
Determining Tcal from hot-cold load measurements in the lab

13. ALMA band1-10 receivers
2007 ALMA : two-load chopper wheel calibration（1%）
Ambient load at 20℃ and hot load at 70℃

14. GBT 4mm receiver
2011，GBT 4mm receiver : two-load chopper wheel calibration
Ambient load and cold load(300K\80K)
two beams on same elevation，4.7 arcmin , 5 S

15. the sample of GBT 4mm receiver

17. Onsala 3mm & 4mm receiver

18. The sample

19. The scheme of 3mm & 4mm receiver

20. Scheme

21. Scheme

22. Thanks!