Hamamatsu PMT Photomultiplier Tube R331-08 with Matching Base


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Product Overview

Hamamatsu PMT R331-08 Photomultiplier Tube with Matching Base

Condition: Used, clean, and in good physical condition. Previously installed in a Packard Tri-Carb liquid scintillation counter.

General Description:

The Hamamatsu R331-08 is a high-performance head-on type photomultiplier tube (PMT) designed for ultra-low light detection applications. This PMT features:

Key Specifications:

  • Photocathode Type: Bialkali
  • Effective Photocathode Area Diameter: 46 mm
  • Spectral Response Range: 300 - 650 nm
  • Peak Wavelength: 420 nm
  • Tube Diameter: 51 mm
  • Typical Anode Luminous Sensitivity: 60 A/lm
  • Typical Anode Radiant Sensitivity: 40 mA/W
  • Typical Gain: 5 x 10^5

Features and Benefits:

  • Includes matching voltage divider base for proper dynode voltages
  • Extremely sensitive light detector for ultra-low light applications
  • Multiplies signal from incident photons into measurable electrical pulse
  • Ideal for spectroscopy, particle physics, medical diagnostics, and analytical instruments

The Hamamatsu R331-08 PMT with matching base offers exceptional performance and reliability for demanding low-light detection applications.

What is a Photomultiplier Tube (PMT) and How Does it Work?

A photomultiplier tube (PMT) is an extremely sensitive vacuum tube device used to detect and amplify low levels of light. It consists of the following key components:

  • Photocathode: A photosensitive surface that converts incident photons into electrons via the photoelectric effect
  • Electron Multiplier: A series of dynodes that multiply the initial photoelectrons through secondary emission, creating an avalanche of electrons
  • Anode: Collects the multiplied electrons, producing an output current proportional to the incident light intensity

Operating Principle

The PMT operates based on the following steps:

  1. Photons enter the vacuum tube and strike the photocathode, causing it to emit photoelectrons.
  2. The photoelectrons are accelerated and focused onto the first dynode by an electric field.
  3. Upon striking the dynode, secondary electrons are emitted, multiplying the number of electrons.
  4. This process is repeated through successive dynodes, creating an avalanche of electrons.
  5. The multiplied electrons are collected by the anode, producing an output current proportional to the initial light intensity.

The high gain of PMTs, typically ranging from 105 to 108, allows for the detection of extremely low light levels, even down to single photons.

Key Features

  • High sensitivity and low noise
  • Fast response time (nanosecond range)
  • Large photosensitive area
  • Wide spectral range (UV to near-infrared)
  • High gain and amplification


PMTs are widely used in various applications that require low-light detection, such as:

  • Spectroscopy (fluorescence, Raman, etc.)
  • Medical imaging (PET, SPECT, etc.)
  • Particle physics experiments
  • Astronomy and astrophysics
  • Analytical instruments
  • Scintillation counting

About Hamamatsu Photonics

Hamamatsu Photonics is a leading Japanese manufacturer of optical sensors, light sources, and photonic systems. Founded in 1953, the company has over 65 years of experience in developing cutting-edge photonic technologies for scientific, industrial, and medical applications.

Pioneering Innovations

Hamamatsu is renowned for its pioneering innovations in photomultiplier tubes (PMTs), photodiodes, image sensors, and other optoelectronic devices. The company's products have played a crucial role in advancing fields such as:

  • Particle physics and astrophysics research
  • Medical imaging and diagnostics
  • Analytical instrumentation
  • Semiconductor manufacturing
  • Optical communications

Quality and Reliability

Hamamatsu places a strong emphasis on quality and reliability, adhering to strict quality management systems and industry-specific testing standards. The company's products are known for their exceptional performance, durability, and precision, making them trusted choices for demanding applications worldwide.

Commitment to Innovation

With a dedication to continuous innovation, Hamamatsu invests heavily in research and development, allocating at least 9% of its annual revenue to R&D efforts. The company's Central Research Laboratory and Tsukuba Research Center are at the forefront of exploring new photonic technologies and applications, ensuring Hamamatsu remains a leader in the field.

Global Presence

Hamamatsu Photonics has a global presence, with subsidiaries and sales offices across the Americas, Europe, Asia, and Oceania. This worldwide network allows the company to provide localized support and solutions tailored to the specific needs of customers in different regions.

By choosing Hamamatsu's PMT Photomultiplier Tube R331-08, you can be confident in the product's quality, reliability, and the company's commitment to advancing photonic technologies for a better world.


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Item was as described, and very fast delivery!

5 stars across the board for every seller rating category, and I would buy from this seller again. And per my request, the capacitors were also very well packed for safe delivery.

Bruce B.

Obtainium have been a very helpful seller to me.

In recent times I have had a few items go astray enroute to my address in Australia. This seller was most helpful & encouraging, regarding the onward tracking & eventual safe delivery of this item. This item's arrival in good condition was a joy to me as, it was a rare part that fitted my military comms. Well done seller. I would gladly recommend this seller to all potential buyers.

Jean-Pierre H.

The item was as described and in good and working condition.

Delivered as promised. I would order again if store has anything else I may need. THANK YOU!

Robert L.

Super Duper Fast Shipping.

Item As Described. Packaged Nicely, What A Seller.

Wayne L.

Product shipped quickly and arrived in good shape

J. Fong


The instrument was well packed. It is in extremely good condition. It passed all preliminary tests.

Raymond W.

Item looks better than described, looks brand new and works great.

My old buffer was 50 years old and I sent it to buffer heaven, thanks.

Mike H.

Just what the doctor ordered.

Good supply and price. Thxs

Ralph M.

As advertised. Would buy from again.

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Perfect transaction, pleasure to deal with.

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