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Event Triggers

  With the area layout described in Sec. 2.2.4, it is possible to construct both a single arm and a two arm coincident trigger. The two arm trigger is used to detect the two approximately anticollinear photons emitted after the single charge exchange reaction tex2html_wrap_inline4942. It incorporates both the CsI and the NaI detectors, as well as the B0tex2html_wrap_inline5072B1 coincidence. The trigger thresholds on the CsI and NaI arrays are set as described in Sec. 2.2.5. The timing of the two arm trigger, shown in Fig. 2.10, is such that the CsI array starts the time to digital converter (TDC).

  figure714
Figure 2.10: Reconstruction of the signals for the two arm trigger configuration (CsItex2html_wrap_inline5126 NaI Inner tex2html_wrap_inline3090 (B0tex2html_wrap_inline5126 B1).

The two single arm triggers are comprised of the B0tex2html_wrap_inline5072B1 coincidence, and one of either the CsI or NaI detectors. In this way, it is possible to detect the photons from the single charge exchange reaction and the 129 MeV photon from the pion capture reaction tex2html_wrap_inline4806. Like the two arm trigger, the thresholds for triggering the arrays are set as noted in Sec. 2.2.5. The timing of each single arm trigger is determined appropriately by the CsI and NaI arrays. The CsI single arm trigger configuration is shown in Fig. 2.11.

  figure724
Figure 2.11: Reconstruction of the signals for the CsI one arm trigger configuration (CsItex2html_wrap_inline5126 (B0tex2html_wrap_inline5126 B1)).

The rates for the single arm and two arm triggers depend on that of their components. These trigger component rates for the 116 MeV/c beam runs are summarized in Table 2.3. The schematic of the electronics used in the 1997 beam time are shown in Figs. 2.12 through 2.20.

  table734
Table 2.3: Experimental rates for 1997 Panofsky Ratio measurement.

  figure744
Figure 2.12: First of eight panels showing a schematic of the electronics used during the 1997 beam time. Drawing courtesy of Michael Dugger, Arizona State University.

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Figure 2.13: Second of eight panels showing a schematic of the electronics used during the 1997 beam time. Drawing courtesy of Michael Dugger, Arizona State University.

  figure758
Figure 2.14: Third of eight panels showing a schematic of the electronics used during the 1997 beam time. Drawing courtesy of Michael Dugger, Arizona State University.

  figure765
Figure 2.15: Fourth of eight panels showing a schematic of the electronics used during the 1997 beam time. Drawing courtesy of Michael Dugger, Arizona State University.

  figure772
Figure 2.16: Fifth of eight panels showing a schematic of the electronics used during the 1997 beam time. Drawing courtesy of Michael Dugger, Arizona State University.

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Figure 2.17: Sixth of eight panels showing a schematic of the electronics used during the 1997 beam time. Drawing courtesy of Michael Dugger, Arizona State University.

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Figure 2.18: Seventh of eight panels showing a schematic of the electronics used during the 1997 beam time. Drawing courtesy of Michael Dugger, Arizona State University.

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Figure 2.19: Eighth of eight panels showing a schematic of the electronics used during the 1997 beam time. Drawing courtesy of Michael Dugger, Arizona State University.

  figure800
Figure 2.20: One of eight panels showing a schematic of the electronics used during the 1997 beam time. Drawing courtesy of Michael Dugger, Arizona State University.


next up previous contents
Next: Tomography of Scintillators Up: Electronics and Trigger Configurations Previous: Components of Event Triggers

Penny Slocum
Fri Apr 2 00:36:38 EST 1999