Title Solar Radio Recombination Lines Pi A. O. Benz Time 10 hrs 1. Solar Radio Recombination Lines Arnold O. Benz, Christoph Keller 2. Clark et al. (1995) have reported the detection of the H19-alpha line in the 350?m band. No line in the millimeter band has been detected yet in the solarmillimeter or sub-mm radiation. The extremely high sensitivity of ALMA and its spatial resolution may help to discovered them. Their detection would represent direct verification of dielectronic recombination processes in the low corona and transition region, and would offer the unique possibility of measuring the magnetic field strength in those regions through the Zeeman effect. 3. Number of sources: one 4. Coordinates: Follow solar orbital motion and solar rotation ecliptic, i.e. +- 23 degrees declination moving target ! Time critical: no 5. Spatial scales: 5.1. Angular resolution (arcsec): better than 0.1" 5.2. Range of spatial scales/FOV (arcsec): small mosaic (optional: indicate whether single-field, small mosaic, wide-field mosaic...) 5.3. Single dish total power data: yes/no yes 5.4. ACA: yes/no if available 5.5. Subarrays: yes/no no 6. Frequencies: 6.1. Receiver band: Band 3, 6, 7, or 9 6 6.2. Lines and Frequencies (GHz): one line 6.3. Spectral resolution (km/s): 0.1 km/s 6.4. Bandwidth or spectral coverage (km/s or GHz): 1 GHz 7. Continuum flux density: 10^6 Jy 7.1. Typical value (Jy): (take average value of set of objects) 10^6 Jy 7.2. Required continuum rms (Jy or K): 100 Jy 7.3. Dynamic range within image: 10 db 9. Polarization: yes/no (optional) yes 10. Integration time for each observing mode/receiver setting (hr): 1 second 11. Total integration time for program (hr): 10 hr 12. Comments on observing strategy: Start with short observing periods to test feasibility ************************************************************************ -------------------------------------------------- Review v2.0: 3.1.2 unchanged Solar Radio Recombination Lines Benz This would use total power and would use the ACA but does not provide details. I would think that all of the flux would be important for this experiment. It aims at 0".1 resolution. It requests 0.1 km/s over 1 GHz, which is not available with the ALMA correlator. Closest (ref Memo 556) is Mode 8 which provides 0.32 km/s resolution: Mode8 16 1 GHz 4096 244 kHz 0.32 km/s 2-bit x 2-bit Nyquist 512 msec 0.88 This uses two polarizations. If sensitivity and polarizations are not an issue, Mode 2 will do: 2 16 1 GHz 8192 122 kHz 0.16 km/s 2-bit x 2-bit Nyquist 512 msec 0.88 which gains a factor of two in resolution. Reply: Mode 2 is a good start. There is no reason to change the DRSP.