Double escape peak

Figure 12.7 presents the spectrum of Na. The single- and double-escape peaks due to the 2.754-MeV gamma are clearly shown. The single- and double-... 

Figure 12.7 A gamma spectrum showing single- and double-escape peaks (from Chap. 4.4.2 of Bertolini and Coche).

The double-escape peak efficiency is important if the energy of the gamma E is greater than about 1.5 MeV, in which case pair production becomes important. The energy of the double-escape peak, equal to P — 1.022 MeV, is used... 

The double- and single-escape peak efficiencies are used with semiconductor detectors only. In the above definitions, if the total detector efficiency is replaced by intrinsic, the corresponding full-energy, single-, and double-escape peak efficiencies are also considered intrinsic. 

SE, DE Single and double escape peaks are 511 and 1,022 keV below the full energy peak of high-energy photons that can produce an electron-positron pair. These peaks are produced when one or both annihilation photons leave the detector. 

AE Between the single escape and double escape peaks there are events from Compton scattering of both escaping 511 keV photons, which leave the sensitive volume. Their... 

Pair production - total absorption, followed by possible partial or complete loss of annihilation quanta. Complete loss produces the single and double escape peak. Counts appearing between the Compton edge and the full energy peak are due to multiple interactions of whatever type. 

Single and double escape peaks from the gamma-rays of greater than 1022keV can be expected. Not all were observed, however. 

S, single escape peak D, double escape peak Parentheses, indicate not observed. Random summing is with 22keV Ag K X-rays from decay of Cd. 

DOUBLE ESCAPE PEAK An extra peak in a spectrum due to the loss of two photons of 511 key energy each during the absorption of a high energy gamma-ray. See escape peaks. 

ESCAPE PEAKS Extra peaks often Seen in a gamma spectrum that contains full-energy peaks greater than 1022 key. They are caused by the escape from the detector of one or two annihilation photons of 511 keV each. The single escape peak is at (full-energy -511) keV the double escape peak is at (full-energy -1022) keV. 

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