The Sciencetech PMH-01 Photon Counting PMT Module is a self contained unit with built-in electronics and PMT. The system includes a power supply as well. The photon count pulses is both displayed on the unit's built-in LCD display and also available as a read-out through an output BNC connector. An optional PCI counter card and Sci-Spec software allows the photon counts to be read into a Windows based PC for analysis. There are three built-in PMT selections to choose from.

Photon Counting PMT Module
The photon counting head used has low power consumption (max 0.5W). It is already adjusted for best S/N ratio. There is no additional adjustment necessary to start the operation. Internally, there is built in PMT, high-speed amplifier, discriminator, high voltage power supply, and a LCD display. The output signal can be read via a BNC connector to an external data acquisition system or computer interface.

Computer Interface
In addition to seeing the photon counts on the LCD display, it can also be read off the BNC connector. However, an optional data acquisition system consisting of a PCI counter board and Windows based Sci-Spec software application is required. The Sci-Spec software reads the photon counts via the PCI counter board. Both PCI counter and Sci-Spec software must be purchased separately. Please note that if you have purchased a Sciencetech multi-channel detector such as a CCD detector or photo-diode array detector, it already comes with Sci-Spec and the PCI counter board option. There is no need to repurchase these two items for the Photon Counting PMT module.

The BNC connector output gives off the actual number of photon count pulses detected in real time for the PCI counter board to track. It does not give the displayed count value as shown on the LCD display.

Data Acquisition Speed
Although the PMT and supporting electronics have a pulse pair resolution of 35ns, the PCI counter board that is reading the photon pulses into the computer cannot respond that quickly. It is only a 5MHz board (200ns) and once you consider that it could take more than one clock cycle to process a pulse, its response time is in the microseconds range.

Obtaining 35ns Pulse Pair Resolution
To obtain 35ns pulse pair resolution, the counter board needs to be upgraded to a 80MHz board which is fast enough to support it, but special development is required. Please contact a Sciencetech Application Sales Specialist for details.

Mounting Mechanism
Sciencetech's PMT Housing uses a quick release mechanism with two side screws to mount the PMT Detector onto Sciencetech monochromators without the need for re-alignment. The monochromator output port 9000M-PMT needs to be ordered with this corresponding quick release mount.

Tube Selection Specifications

• Peak Wavelength Sensitivity: 400nm
• Dark Count (30min in darkness): 30s^-1

Technical Specifications

Photon Counting Head
• Operating Temperature Range: 5 to 40 °C
• Storage Temperature Range: -20 to 50 °C
• Counting Linearity: 2.5 Mcps
• Pulse Pair Resolution: 35 ns
• Output Pulse Width: 30 ns
• Output Logic: TTL, positive
• Input Voltage: +5 V
• Input Current at 2.5 Mcps Output: max. 80 mA
• Output Signal Cable: RG-174/U
• Dark Count (Typical): 400 cps
• Dark Count (Max.): 800 cps
• LCD/Counter Unit Refresh Time: 6 s
• Display Type: 8 digit LCD