1. STIS CCD: Housing Temperature, Darks, and Charge Transfer Inefficiency Michael A. Wolfe June 17, 2010 Co-Investigators: W. V. Dixon, P. Goudfrooij, T. Wheeler

2. Topics  Housing Temperature  Scaling Relation for Darks  Charge Transfer Inefficiency Extended Pixel Edge Response

3. Housing Temperature vs. Time Plot

4. Scaling Relation Scaling Equation: (dark image)*(1 + slope*(T O - T))

5. Dark Rate Ratio vs. Temperature Plot

6. Fractional Change in Dark Rate (Old Data)

7. Fractional Change in Dark Rate (New Data)

8. Histogram of Dark Rate

9. Dark Normalization New slope is 0.056/ o C ± 0.004/ o C New reference temperature is 22.0 o C Peak of histogram is -1.8 e-/s/pix Standard deviation is 0.4565 e-/s/pix Range of dark current is -2.2865 e-/s/pix to -1.3136 e-/s/pix

10. Charge Transfer Inefficiency Extended Pixel Edge Response Test at ≈ 12056.6 e - signal level (Janesick et al. 1991) Reference Janesick, J. R., Soli, G., Eliot, T., & Collins, S., 1991, “The Effects of Proton Damage on Charge-Coupled Devices”, in Proc. SPIE, 1447, 87

11. Extended Pixel Edge Response Test Plot

12. Temperature/CTI Parameters  Operating Temperature -83 °C  Clocking Times Parallel: 23.2 ms Serial: 22 μs  E center trap, P-V complex  -90 °C to -60 °C, 100 μs (parallel)  Largest slope for STIS is at -80 °C  -40 °C (serial)

13. CTI Dependence on Temperature Plot

14. CTI Dependence on Time Plot

15. Future Work Investigate the seeming dependence of CTI on temperature. Investigate the “settling” of the CCD. …. just to name a couple.