(Cd,Mn)Te detectors for characterization of X-ray emissions generated during laser-driven fusion experiments

Abstract

Abstract-We present our measurements of (Cd,Mn)Te photoconductive detectors (PCDs), fabricated for the goal of measuring both the temporal and spectral dependences of X-ray emissions generated from laser-illuminated targets during the inertial confinement fusion experiments. Our Cd 1-x Mn x Te (x = 0.05) single crystals, doped with V, were grown using a vertical Bridgman method and, subsequently, annealed in Cd for the highest resistivity (~10 10 Ωcm) and a good mobility-lifetime product (~10 -3 cm 2 /V). The 1-mm-and 2.3-mm-thick detectors were placed in the same housing as two 1-mm-thick diamond PCDs. All devices were pre-screened by a 7.6-mm-thick Be Xray filter with a frequency cutoff of 1 keV. The incident shots from the OMEGA laser were 1-ns-long square pulses with energies ranging from 2.3 kJ to 22.6 kJ, and the PCDs were biased with 5000 V/cm. The response amplitudes and rise times of our (Cd,Mn)Te PCDs were comparable with the diamond detector performance, while the decay times were 4 to 10 times longer and in the 2-5 ns range. We observed two X-ray emission events separated by 1.24 ns. The first was identified as caused by heating of the target and creating a hot corona, while the second one was from the resulting compressed core. For comparison purposes, our testing was performed using ~1 keV X-ray photons, optimal for the diamond PCD. According to the presented simulations, however, at X-ray energies >10 keV diamond absorption efficiency drops to <50%, whereas for (Cd,Mn)Te the drop occurs at ~100 keV with near perfect, 100% absorption, up to 50 keV.

Picosecond (Cd,Mg)Te detectors for both optical and x-ray photons

“…(Cd,Mg)Te is a ternary compound with a variable direct energy gap EG, ranging from 1.5 eV to 3.1 eV by modifying the Mg content. The Cd1-xMgxTe (x is between 0 to 0.45) crystal exhibits the zinc blende structure and it is the latest member of ternary alloys that include (Cd,Zn)Te and (Cd,Mn)Te, both well known for X-ray detection applications, 6 with (Cd,Mn)Te being also a semi-magnetic semiconductor. 7 CMT single crystals possess all the necessary qualities for the optimal radiation detector, 8 like high material density (5.83 g/cm 3 ), high effective mass (49.5), ultrahigh resistivity (∼10 10 Ωcm, when In or V doped), and good electron mobility lifetime (μe) product (~10 −4 cm 2 V −1 ).…”

Time-resolved, nonequilibrium carrier and coherent acoustic phonon dynamics in (Cd, Mg)Te single crystals for radiation detectors

“…Currently, cadmium zinc telluride [(Cd, Zn)Te or CZT] is the accepted material of choice; however, because of the large Zn segregation constant in CdTe, it has poor crystal growth yield making it costly to fabricate in large volumes [1,2]. Proposed alternatives to CZT are cadmium manganese telluride [(Cd, Mn)Te or CMnT] single crystals [3,4] and most recently developed cadmium magnesium telluride [(Cd, Mg)Te or CMgT] [5]. All of the above materials are ternary alloys that contain tellurium, which assures their very high stopping power and 100% absorption efficiency for x-ray photons with energies above 100 keV [4].…”

“…Proposed alternatives to CZT are cadmium manganese telluride [(Cd, Mn)Te or CMnT] single crystals [3,4] and most recently developed cadmium magnesium telluride [(Cd, Mg)Te or CMgT] [5]. All of the above materials are ternary alloys that contain tellurium, which assures their very high stopping power and 100% absorption efficiency for x-ray photons with energies above 100 keV [4]. However, CMgT possesses all of the other necessary qualities for an optimal radiation detector, i.e.…”

Photoconductive and electro-optic effects in (Cd,Mg)Te single crystals measured in an experiment-on-chip configuration

“…(Cd,Zn)Te is one of the main materials used as an x-ray and gamma-ray detector and is commercially available [6,7], while (Cd,Mn)Te is among the best-known diluted magnetic semiconductors [8,1]. In addition, (Cd,Mn)Te has been known for its interesting properties, both magneto-and electro-optic [9,10], and recently has been successfully implemented in time-resolved x-ray detectors [11].…”