Haluk YÜCEL, Ayşe SOLMAZ, Asena KURT, Tolga İNAL, Doğan BOR

DİSK KAYNAK GEOMETRİSİ İÇİN 30-670 keV GAMA IŞINI ENERJİ ARALIĞINDA CdZnTe DETEKTÖRÜNÜN DEDEKSİYON VERİMİ

Bu çalışmada, dedektör hassasiyeti, temelde iki parametreye; enerji çözme gücü ve dedeksiyon verimine bağlı olduğundan, belirli bir enerji aralığında CdZnTe dedektörlerin spektroskopik özellikleri incelenmiştir. Bu amaçla, radyoaktif disk kaynaklar kullanılarak bir 5x5x5 mm3 CdZnTe dedektörle elde edilen gama spektrumlarının analizinden enerji çözme gücü (yarı yükseklikteki tam genişlik, YYTG cinsinden) ve pik biçimleri (pik-vadi oranı, P/V cinsinden) belirlenmiştir CdZnTe dedektörünün disk kaynak geometrisindeki dedeksiyon verimi, 30-670 keV enerji aralığında ölçülmüştür. Bu enerji aralığı, medikal görüntülemede kullanılan radyoizotopların, nükleer alandaki zenginleştirilmiş uranyum, plütonyum izotoplarının ve kullanılmış yakıt içindeki aktivasyon/fisyon ürünlerinin yayınladığı X- ve gama ışınlarının hemen hemen tümünü kapsar. Belirli bir mesafeye yerleştirilen disk kaynaklar ile CdZnTe dedektör için gama dedeksiyon veriminin enerjiye bağlılığını gösteren yarı-ampirik fonksiyon önerilmiştir. Ancak ölçülen verim değerlerinde, özellikle yüksek enerjilerde, 200-670 keV aralığında önemli derecede düşmeler gözlenmiştir. Bu durum, esas olarak kristal kusurlarına bağlı olan ve yükün etkin toplanamamasının bir sonucu olarak, fotopik alanlarında kayıpların olduğunu göstermektedir. Bunlar, geleneksel CdZnTe dedektörlerin bilinen yetersizlikleridir.

Anahtar Kelimeler:

CdZnTe dedektör, disk kaynak, enerji çözme gücü, dedeksiyon veya fotopik verimi, gamaışını spektrometrisi.DETECTION

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