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I am planning to buy a photomultiplier tube for my lab experiment but I am not sure how to use it exactly. For eg. I was looking at the hamamatsu HC-120-05. http://mi-lasers.com/wp-content/uploads/HAMAMATSU-HC120_series.pdf

  1. It is written in the datasheet that the operating voltage is -1100V. Is that the supply voltage?

  2. How do you see the output from a coaxial cable.using oscilloscope?

  3. Do I have to use another amplification circuit to see very low light output?

Another one i checked was senstech P30A-03 http://www.sens-tech.com/assets/media/files/Data%20Sheets/P30A_iss2.pdf This one says power input is +/-5V and HV control sensitivity is -1000V. WHat's that?

Anyone who has ever use any photomultiplier please help. Its very expensive, I don't want to buy it without understanding how to use it.

Thanks so much.

Kashish
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  • have you read that datasheet? – PlasmaHH Oct 30 '17 at 22:27
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    The datasheet suggests to me that they have already designed the HV power supply for you. From the datasheet, "The high voltage needed to power the photomultiplier is generated with a 10 stage Cockcroft-Walton Voltage multiplier with one stage per dynode." This means (to me) that the "supply voltage" of at most $\pm 18:\textrm{V}$ is the issue for you to worry about. Supply it with the recommended $\pm 15:\textrm{V}$ seen in the figure on the last page of the datasheet. If you are not able to read this datasheet well, get some advice from Hamamatsu! They want you to succeed. – jonk Oct 30 '17 at 22:54
  • You should be aware that you can easily damage PMTs. You may accidentally create very high interdynode currents when an operating PMT is exposed to too much light. The electron bombardment of dynodes release ions and if enough of that occurs then breakdown will also occur. The PMT will just glow. The PMT is then left with an ion-damaged photocathode and filled with gas. A good design can help protect against this and I hope the unit you are considering is safe in this way, or that you will treat it with kid gloves. – jonk Oct 30 '17 at 22:58
  • Finally, I hate to say it but you sound as though you are without any clues. Who told you that you needed a PMT and why did they say so (what do you recall of it?) What exactly is your lab experiment, in detail? Do you know the range of irradiances you are concerned about; the watts per steradian and your optical arrangement and how all that reduces down to the needed sensitivity of your equipment; the wavelengths you are dealing with; etc.? You need to write a lot more, I think. – jonk Oct 30 '17 at 23:03
  • Thanks for all the information @jonk . I am required to measure very low intensity light from chemilluminescence(chemical reaction that gives out light). Pmt is needed to know the light luminosity or wattage that the reaction actually produces so that I can choose appropriate photodiode according to it. – Kashish Oct 31 '17 at 15:04
  • As you mentioned I will talk to hamamatsu about how to make the optical arrangement to perform the experiment. Your suggestions are great. Based on these I will prepare the whole setup(as you said it cannot be exposed to too much light, so that the pmt should always be in dark,maybe in a box,does that sound right?) @jonk – Kashish Oct 31 '17 at 15:04
  • What ratio of minimum-to-maximum light must you measure? And with what uncertainty must you measure? at minimum? at maximum? – analogsystemsrf Oct 31 '17 at 15:29
  • @analogsystemsrf The problem is that I don't know the amount of light in any unit(which is why i need the pmt). But for reference I can tell you that with a simple photodiode with a sensitivity of 0.2A/W, the light generates a photodiode output current in picoamperes(so it means the light,both minimum and maximum,is in the range of a few femtowatts). – Kashish Oct 31 '17 at 15:45
  • @Kashish I've used Si photodiodes to reach signal currents of $10:\textrm{fA}$. It's work to get down there. But it is NOT hard at all to reach into the low picoamps with photodiodes. – jonk Oct 31 '17 at 17:03
  • @jonk can you share with me the photodiodes that you used and how much amplification did you provide(using a transimpedance opamp I believe)? I have reached fA too (using hand-soldered through-hole components to give a 10^17 amplification) but its a very sensitive circuit which uses 1 and 10 Gohm resistors making it difficult to develop on a pcb. Thanks! It will be of great help. – Kashish Nov 01 '17 at 21:15
  • @Kashish Have you examined any Burr Brown parts? For extremely low currents I used integrators. I have also used HUGE resistor values, but even IC packages LEAK too much and for gain changes I had to use one of some very special COTO relays to avoid leakage in that packaging. – jonk Nov 01 '17 at 21:35
  • @Kashish You might look at the DDC112, for example. I've also used the ACF2101. And other Burr Brown parts. Worked with one of the IC designers for both parts as part of the work. For example, I can tell you that you'd better not exceed $7:\mu\textrm{A}$ on the DDC112 input due to one of the aluminum metallization paths being insufficient to carry more without diffusing out over time. I look for bulk resistivities near $10^{14}$ or better (no IC package comes close to meeting this.) I have had to buy dice and wire bond and use tiny TE cooler stacks in a TO-3 thingy to get what I wanted. – jonk Nov 01 '17 at 22:59
  • @jonk Thanks. I will look into these. I thought about using integrators too. Could you kindly tell me which Si photodiode you used? – Kashish Nov 02 '17 at 12:37
  • @Kashish Give me some time. I think I may have a few of them somewhere here. I might be able to remember from looking in a catalog. But I may as well give you the right info. I also called and spoke with Diodes, Inc about the possibility of doing a special diode and I found them, then, to be quite encouraging about the idea. Good folks, then, anyway. Never did it, though. (I had been doing my own 3D integral calcs to design a diode.) – jonk Nov 02 '17 at 17:05
  • Great! please let me know when you find the diode part number. Thanks for your help! – Kashish Nov 02 '17 at 18:34

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from what I had gathered from the datasheet that you sent I will answer your questions. in the order that they appear.

  1. the supply voltage is something that is generated withing the tube itself the only thing that you need to is adjust the control voltage.

The text said to the following.

"Monitor the voltage between the white (Control Wire) and the black (0V) the photo-multiplier operating voltage is 10000x that of the control." (Be very careful)

  1. Find someway to bridge the signal wire to a probe and make sure that you have a proper grounding as well.

  2. No the signal should be powerful enough or your equipment should have an external amplifier.

One thing to keep in mind is to wait a bit when you have everything set up to let the tube warm up, warm up time is all so stated in the documentation.

Good Luck.

Ben Madison
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