V102AR406/3.5M-X6 Detector Assembly

1Overview

The V102AR406/3.5M-X6 is a turnkey scintillation detector assembly combining a large NaI(Tl) crystal with a high-quantum-efficiency photomultiplier tube (PMT), aluminum housing, and a standard 14-pin connector for direct coupling to a digital multichannel analyzer base. The package is compact enough for vehicle-roof mounting or aircraft integration while delivering the large active volume needed to achieve useful detection sensitivity at environmental gamma flux levels.

At 4 liters (14.7 kg) of NaI(Tl), this detector is among the largest practical field-deployable scintillation assemblies. The quartz optical window keeps low-energy background contributions suppressed, and the SBA-cathode PMT maximizes photoelectron yield from the NaI emission band centered near 415 nm. Together, these choices produce an energy resolution below 8% FWHM measured at 662 keV under the off-axis geometry typical of airborne survey.

2Features

• 4-liter (14.7 kg) NaI(Tl) scintillation crystal, 102 × 102 × 406 mm (4" × 4" × 16")
• Low radiological background due to quartz optical window
• High quantum efficiency (HQE) SBA-cathode photomultiplier tube, 89 mm diameter
• Standard 14-pin connector, compatible with digital MCA bases
• 1.0 mm aluminum housing: lightweight and field-durable
• Energy resolution <8% FWHM at 662 keV, measured sideways halfway at 30 cm off-axis
• Wide operating temperature range: −20 to +65 °C
• Positive high-voltage polarity; compatible with standard NIM and digital bases
• Optimized efficiency/energy-resolution balance for mobile survey

3Description

Crystal and Optical Coupling

The detector uses a NaI(Tl) crystal measuring 102 × 102 × 406 mm, a format often designated 4" × 4" × 16". NaI(Tl) remains the established workhorse for environmental gamma surveys: its emission peak near 415 nm couples efficiently to bialkali and SBA photocathodes, and its high light yield (relative index 100) delivers the photoelectron statistics needed for sub-10% FWHM resolution at the 662 keV cesium-137 reference line.

The quartz optical window is a deliberate choice for background reduction. Borosilicate glass windows contain trace amounts of naturally occurring radioactive material that can contribute low-energy counts. Quartz provides a cleaner optical interface without that background penalty, which matters when monitoring at environmental flux levels where signal-to-noise margins are tight.

Photomultiplier Tube

Crystal readout is via an 89 mm diameter PMT with a super bialkali (SBA) photocathode. SBA cathodes offer higher quantum efficiency in the 350 to 450 nm range compared with standard bialkali, translating directly into better photoelectron yield per scintillation event and improved energy resolution. Operating voltage is positive polarity, +700 V to +1000 V, compatible with the voltage-divider bases commonly used with digital MCA systems.

Housing and Mechanical

The assembly is enclosed in 1.0 mm thick aluminum. This wall thickness balances mechanical protection against crystal and PMT damage with weight economy for mobile applications. The maximum overall envelope, measured to the tip of the 14-pin connector, is 109 × 109 × 538 mm. The 14-pin standard connector provides direct mechanical and electrical coupling to compatible digital bases without adapters or custom wiring.

Environmental and Thermal Performance

The operating temperature range of −20 to +65 °C covers the conditions encountered in airborne and vehicle-mounted survey: cold early-morning flights at altitude and hot-day ground operations in desert or tropical environments. The temperature gradient limit of 10 °C per hour protects the NaI(Tl) crystal from thermal shock, which can crack a large-volume hygroscopic crystal if temperature changes are imposed too rapidly. Field users should allow the detector to equilibrate before powering up in extreme ambient conditions.

4Technical Specifications

5Applications

The V102AR406/3.5M-X6 is designed primarily for mobile and airborne environmental gamma survey. Its large crystal volume maximizes detection efficiency over a wide footprint while the controlled energy resolution keeps spectral peaks identifiable for isotope-specific analysis. Typical deployment scenarios include:

• Airborne Radiological Survey: Mounting under the fuselage or in the cargo bay of small aircraft or helicopters for large-area background mapping and anomaly detection
• Vehicle-Mounted Survey: Fixed or semi-permanent installation on survey trucks and SUVs for road-network radiological baseline mapping
• Environmental Monitoring Networks: Fixed-station or semi-portable monitoring at nuclear facilities, waste sites, or border control points
• Emergency Response: Rapid-deployment vehicle kits for post-incident environmental characterization and contamination mapping
• Nuclear Security: Mobile interdiction units requiring high sensitivity to weak or shielded sources at patrol speeds
• Background Baseline Studies: Long-dwell counting to establish natural background variability before facility construction or decommissioning

6Ordering & Contact