Lithium-containing semiconductor crystals for radiation detection
- PDF / 6,427,815 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 111 Downloads / 234 Views
Lithium-containing semiconductor crystals for radiation detection Ashley C. Stowe1, Joe Cochran1, Pijush Bhattacharya2, Eugene Tupitsyn2, Brenden Wiggins2, Michael Groza2, Arnold Burger2 1
Y-12 National Security Complex, Oak Ridge, Tennessee, USA
2
Fisk University, Nashville, Tennessee, USA
ABSTRACT Semiconductor materials have shown promise as ionizing radiation detection devices; however, to be used as a neutron detector, these materials require the addition of a nucleus with a large neutron absorption cross section (such as 10B or 6Li) to capture thermal neutrons and convert them into directly detectable particles. A semiconducting material that contains the neutron absorber within its regular stoichiometry has the potential to be more efficient than a layered or heterogeneous device at transferring the kinetic energy of the charged particle into the semiconducting material. One class of materials that has shown promise is Li-containing AIBIIIXVI2 compounds such as LiGaTe2, LiGaSe2, and LiInSe2. These materials have band gaps (2-3.5 eV) appropriate for room-temperature detection of thermal neutrons and would be the first detection material that is simultaneously, exquisitely sensitive to thermal neutrons; is insensitive to gammas; and acts as a direct conversion device. A vacuum distillation process provided highpurity lithium metal for AIBIIIXVI2 synthesis. Single crystals of sufficient bulk resistivity (grown for LiGaSe2 and LiInSe2LiInSe2) showed a distinct photo response as well as a clear response to alpha particles. Additional radiation measurements indicated that a 6 mm x 7 mm x 1.33 mm crystal of LiInSe2 detected gamma rays, and despite being composed of natural abundance lithium, responded to thermal neutrons as well. INTRODUCTION A worldwide helium shortage has developed in recent years as a result of a limited supply of He and increasing demand for neutron detection materials for scientific and security applications. As a result, research into alternatives to gas detectors (3He or 10BF3) or scintillation detectors (cerium-doped lithium glass) has grown [1]. It is highly desirable to develop a solidstate detector for neutron detection. In much the same way as solid-state CZT detectors have revolutionized gamma-ray detection, a solid-state neutron detector would offer the significant advantages of portability, sensitivity, simplicity, and low cost. A neutron absorber (e.g., 6Li or 10 B) must be used along with a charge collector in such a device. To date, most reports of lithium-containing solid-state neutron detectors have used a lithium conversion layer in conjunction with a silicon diode detector [2]. To obtain a useable thickness of lithium to stop neutrons efficiently, deep holes are etched in the silicon, and a lithium- (or boron-) containing material is conformally deposited into the holes [3]. If, however, the neutron absorber is within the charge generating/collecting device (i.e. the semiconductor), each thermal neutron impinging on the detector crystal has a high probability of reacting wi
Data Loading...
