Two-state modeling of the superheated emulsion detector

Study of gamma ray response of R404A superheated droplet detector using a two-state model

“…Superheated droplets, when exposed to energetic radiation, are expected to decay monotonically. However, when the droplets are irradiated multiple times with a radiationoff period in between successive irradiations, it is observed that the nucleation rate at the beginning of the irradiation considerably increases compared to the rate at the end of the previous irradiation [8,9]. This discrepancy in the nucleation rate data indicates that in SDD the droplets are in two metastable states.…”

“…At thermal equilibrium the droplets in the detector are distributed among the two metastable states. When irradiated the short lived droplets in second metastable state decay much faster than the others in normal metastable state, giving a sharp initial fall in the nucleation rate, after which only the long-lived droplets remain and decay [8,9]. The short lived droplets repopulate from the normal metastable state during the radiation-off period resulting in an increase in the nucleation rate at later irradiations.…”

“…For the preparation of SDD different low boiling point liquids are used, such that at their operating temperature they are in reasonably superheated state and can be used for detection of ionizing radiations. Recent studies also indicated that in superheated emulsion there exist two groups of droplets one having much shorter lifetime than the other [8,9]. The decay of these droplets in SDD has been modeled earlier [9] using a two-state model which explains the ambiguity in the nucleation rate data.…”

“…Recent studies also indicated that in superheated emulsion there exist two groups of droplets one having much shorter lifetime than the other [8,9]. The decay of these droplets in SDD has been modeled earlier [9] using a two-state model which explains the ambiguity in the nucleation rate data. In this paper we have studied the characteristics of R404A (nearly azeotropic blend of C 2 H 3 F 3 , C 2 H 2 F 4 and C 2 HF 5 ; b.p.…”

“…The gamma ray detection threshold temperature of R404A is obtained using a 662 keV 137 Cs gamma ray source. The nucleation parameters, detection efficiency and interstate transition kinetics of the two metastable state is studied using the two-state model [9]. To the best of our knowledge R404A based SDD has not been studied earlier.…”