Electronics and data acquisition

Basic scheme of the data acquisition is along the current Hall C standard DAQ system.

Table 15 summarizes the number of required read-out channels for each detector. Signals from the drift chambers (HDC1, HDC2, EDC) are amplified and discriminated by Nanometrics 277 Amplifier-Discriminator boards (16 ch/board). These boards are mounted on the chambers and timing information of the output ECL signals is recorded by Fastbus TDC (LeCroy 1877). The FB TDC is now commercially unavailable and there is an option to replace the TDC by F1-Chip TDCs newly developed at Jlab if the development is finished in time.

PMT signals will be recorded with ADC (LeCroy 1881) and high resolution TDC (LeCroy 1872A). Since we require very good timing resolution ( $\sigma \sim 50$ ps) for the TOF counters (HTF1X, HTF1Y, HTF2X, HWC1, HWC2, EHOD1, EHOD2, EHOD3), the discrimination of these signals to the logic signals possibly be carried out in the Hall C to have better timing resolution.

Figure 37 shows a conceptual design of the trigger logic. The HKS counters produces the ``K'' trigger and the Enge does the ``electron''. The veto signals such as aerogel Cerenkov signals might be used individually rather than ORed in order to reduce the number of the over-kill events. A simple coincidence module might not be used for the main coincidence circuit. A sophisticated pattern matching logic is suitable for it.

表 15: Detector and read-out electronics summary

Name	Detector	Read-out Method	Channels	HR TDC	TDC	ADC
HKS detectors
HDC1	Drift Chamber	Nanometrics 277	660		660
HDC2	Drift Chamber	Nanometrics 277	720		720
HTF1X	TOF hodoscope (X)	PMT H1949	34	34		34
HTF1Y	TOF hodoscope (Y)	PMT H1949	18	18		18
HAC1	Aerogel Cerenkov	PMT R1250	20	20		20
HAC2	Aerogel Cerenkov	PMT XP4572B/D1	20	20		20
HAC3	Aerogel Cerenkov	PMT XP4572B/D1	20	20		20
HTF2X	TOF hodoscope (X)	PMT H1949	36	36		36
HWC1	Water Cerenkov	PMT H1161	36	36		36
HWC2	Water Cerenkov	PMT H1161	36	36		36
Sub total				210	1380	210
Enge detectors
EDC	Honeycomb DC	Nanometrics 277	1400		1400
EHOD1	TOF hodoscope (X)	PMT H6612	50	50		50
EHOD2	TOF hodoscope (Y)	PMT H6612	50	50		50
EHOD3	TOF hodoscope (Y)	PMT H1949	2	2		2
Sub total				102	1400	102
Grand Total				294	2780	294