Effects of packaging SrI2(Eu) scintillator crystals

Recent renewed emphasis placed on gamma-ray detectors for national security purposes has motivated researchers to identify and develop new scintillator materials capable of high energy resolution and growable to large sizes.

We have discovered that SrI2(Eu) scintillators has many desirable properties for gamma-ray detection and spectroscopy, including high light yield of ∼90,000 photons/MeV and excellent light yield proportionality. We have measured <2.7% FWHM at 662 keV with small detectors (<1 cm3) in direct contact with a photomultiplier tube, and ∼3% resolution at 662 keV is obtained for 1 in.3 crystals. Due to the hygroscopic nature of SrI2(Eu) scintillators, similar to NaI(Tl), proper packaging is required for field use.

This work describes a systematic study performed to determine the key factors in the packaging process to optimize performance. These factors include proper polishing of the surface, the geometry of the crystal, reflector materials and windows. A technique based on use of a collimated 137Cs source was developed to examine light collection uniformity.

Employing this technique, we found that when the crystal is packaged properly, the variation in the pulse height at 662 keV from events near the bottom of the crystal compared to those near the top of the crystal could be reduced to <1%. This paper describes the design and engineering of our detector package in order to improve energy resolution of 1 in.3-scale SrI2(Eu) scintillators crystals.

This article comes from sciencedirect edit released

Medical Filter – IPL Filter

IPL filter is the key optical element for IPL (intense Pulsed Light) machine, which filters the UV wave and reserve the useful wave from 400nm to 1200nm for cosmetic laser, such as photrevujenation, hair removal, vascular and acne treatment. The available wavelength are 550, 560, 570, 590, 615, 645, 695, 755,780 nm.

  • Material:N-BK7 Grade A optical glass, Fused silica, Sapphire crystal.
  • Dimension Tolerance:+/-0.1(General), +/-0.01(High Precision)
  • Thickness Tolerance:+/-0.2 (General), +/-0.005(High Precision)
  • Surface Quality:60/40
  • Clear Aperture:>90%
  • Parallelism<3 arc min. (General) , <5 arc sec.(High Precision)
  • Wavefront Distortion(per 25mm@633nm): λ/2 (General) , λ / 8(High Precision)
  • Bevel(face width x45°):0.2~0.5mm

Available wavelength: 515 ~ 1200, 530 ~ 1200, 550 ~ 1200, 560~ 1200, 570 ~ 1200, 590 ~ 1200,
615 ~ 1200, 645 ~ 1200, 695 ~ 1200, 755 ~ 1200, 780 ~ 1200 nm

Laser Line Bandpass Filter

Laser Line bandpass Filters transmit a well-defined center wavelength of light, with band pass width, while blocking the other unwanted radiation. Central Wavelength from 350 nm to 1550 nm, 350nm, 488nm, 515nm, 560nm, 590nm, 640nm, 755nm, 850nm, 980nm, 1060nm, 1310nm, 1550nm laser line type.
1nm, 3nm, 10nm, 12nm, 25nm, 40nm, and 70 nm Bandpass width etc.

This article comes from wavelength-tech edit released

Common Laser Crystals Dopants

Laser crystals are typically single crystals (monocrystalline material) which are used as gain media for solid-state lasers. In most cases, they are doped with either trivalent rare earth ions or transition metal ions. These ions enable the crystal to amplify light at the laser wavelength via stimulated emission, when energy is supplied to the crystal via absorption of pump light (→ optical pumping).

Compared with doped glasses, crystals usually have higher transition cross sections, a smaller absorption and emission bandwidth, a higher thermal conductivity, and possibly birefringence. (The article on laser crystals versus glasses discusses the differences in more detail.) In some cases, monocrystalline laser materials may be replaced with ceramic gain media, which have a fine polycrystalline structure.

This article comes from rp-photonics edit released

Well-type NaI(Tl) detector efficiency using analytical technique

Highlights

• A new analytical approach for calculation of the full-energy peak efficiency is deduced.
• The method depends on the calculation of the photon path length.
• Separate calculation of factors which related to photon attenuation is introduced.
• The effective solid angle between source-to-detector is calculated.
• Remarkable agreement between measured and calculated efficiencies was achieved.

Well-type detectors play an important role in qualitative and quantitative analysis of low-activity samples, thanks to their pronouncedly high efficiency; this is particularly the case with scintillation detectors. In this work a theoretical approach to calculations of full-energy peak efficiencies of well-type detectors is elaborated.

The approach is based on the concept of the effective solid angle and the efficiency transfer principle. In parallel, ANGLE 4 software was employed to the same aim, using point sources positioned on 2″ × 2″ NaI(Tl) detector axis outside the detector well cavity. The theoretically obtained and ANGLE 4 calculated efficiency values were compared to the measured ones. These comparisons supported/confirmed both the theoretical concept and ANGLE 4 Software validity in well-type scintillation detectors calibration.

This article comes from science-direct edit released