Dear prashanth,

Any detector as such is not designed for giving out only timing or only energy type of signals. The fundamental signal that any detector gives out as a response to radiation interaction in its active volume is a momentary pulse of current. Based on the way in which you process this momentary current pulse the system as a whole either acts as a timing based ( used only for counting purpose) or as a energy signal (used for extracting energy spectrum). My suggestion would be to continue to use whatever detector you have. To get the timing information you can just change the front end electronics from charge sensitive (current integrator) pre-amplifier to a current sensitive(current to voltage converter) pre-amplifier.

I totally agree with Prasanna Gandhiraj. One need to select the corresponding electronics accordingly for energy and timing information . But, intrinsic property of detector like capacitance of the detector ultimately restricts the timing resolution.

Thanks gadir,prasanna, sikdar for answers....... but still i have some doubt..... e.g. for LEGe or HPGe detectors timing information is not so precise because for any detector signal formation depends on the drift of the charges over distances and for Ge this distance is quite large, thats why Ge detectors are not very fast. If i made changes to electronics, it will not give me timing resolution in nsec. If I am wrong please correct me . For my experiments i need a X-ray detector which can give me timing resolution in nsec, so i can study the coincidence events between particles and X-ray.

Currently , I am working in Fission and X ray coincidence. I have used LEPS detector . Taken energy signal from LEPS , put it into MSCF-16 ( which does both energy shaping and give timing OR of all four channels). On the other side, I have used Solar cell for fission fragment detection. Used 142 Preamplifier , put it into TFA and then used TSCA to get logic output for timing. Then used TAC ( start from LEPS and Stop from Solar Cell) and get the TAC signal. I have achieved timing resolution of 500 ns(FWHM) roughly. I am still working to improve it. For any details ,you can ask me. Any further improvement, if it is possible let me know.

This for your information.... With the above metioned technique, and playing little bit in Differentation and Integration of TFA and Threshold of TSCA, we have achieved a time resolution( FWHM ~ 250 nsec or better)

Thanks Sikdar for information.... Basically we are doing same thing in our Xray-particle coincidence experiment.... We are taking enrgy signal from Microstrip detector and putting it into MSCF-16, from where we are taking trigger output to make TAC start...... whereas for TAC stop we are taking energy output from Xray detector, putting it into TFA and then TSCA to make logic output for stop signal. NOTE we are also delaying the signal using about 20 meter 50 ohm lemo cable in TSCA. I think adjustment in delay can give us better results. For extra information, shaping time of X-ray detector is 3-5 micro sec. whereas for Microstrip detector,it is .5 to 1 micro sec. Is this factor (shaping time of two detectors) can play a key role to get the coincidence events?

Hello Prashant

The rising time of the detector output pulse carries the timing information. the best timing performance is generally obtained from detectors with a fast rise time. I think, taking short shaping time you can enhance timing resolution. as Mr. Sikdar wrote, Differentation and Integration of TFA and Threshold of TSCA can help you.

Actually, you are actually doing the other way round... u r using MSCF-16 for Microstrip and I am using it for X ray. Kept 2 micro second shaping time and delayed it ( need to look out for values with standard GATE DELAY GENERATOR) and given it to start to TAC. on the other hand, taken the preamplier signal from 142A ORTEC preamplifier for fission fragment, given to TFA( Diffentiation 20 nsec and integration 500 nsec) and given to TSCA. Play threshold and differentiation to optimize the resolution and also look out you do not miss any fission signal for high threshold. Let me know the progress?

Thanks Sikdar..... I will be in your touch and let you know about the progress whenever next experiment will be carried out.

Ok....:)

You don't say what the energy range of your x-rays are. There are PIN diodes that, in photoconductive mode, will be sub ns in their response. Also there are x-ray streak cameras that go down to ~ ps. These are good from UV to ~20keV.

@ Anthony Are you asking me or Prashant?

Sorry, Prashant. It wasn't a question, just a comment.

Why don't use the LEAK MICROSTRUCTURE (LM) for timing with Xray?

In NIM A 388(1997) 186-192 , in fig.5 (at pag.189) it is reported pulses obtained from a Fe55 source (5.9 Kev)  with a risetime of some nanosecond and several tens of mV in amplitude. Of course if you have to detect  Xrays of more energy you will obtain pulses of greater amplitude ( the LM is a detector working in proportional region) and ,if the case, you can  reduce the HV to the LM to limit the amplitude of pulses.

In PRANAMA Vol.57,No.1,July 2001,pp.115-124,  fig.10 (p.123) reports an example of timing  with the LM using a very simple coincidence-electronics and a Fe55 source: some nanosec. FWHM.

Hi Prashant et al. There is a fairly robust solution to this problem based on micro-pattern gaseous detectors in TPC-configuration (micromegas would be best for this, but one could also use GEM depending on more detailed specs), allowing for a thin entrance window transparent to the X-rays. The rise-times from multiplication itself are pretty fast and usually it is just the time jitter coming from the electron released closest to the multiplication region that determines the time resolution. Although these configurations are popularized in charge-mode one could certainly use current-amplifiers (depending on the time resolution you finally need) as it has been often done. A thin Xenon drift region will make the trick for you nicely. Additionally, with Multi-gap timing RPCs, 100ps-sigma is easy for gammas (with few-% efficiency), although with x-rays you will have problems to cross the fairly bulky structure. I am certain this is doable though.

PIN diodes can provide very good timing informations. The fast rise time of these detectors can be utilised. If tens of ns is ok, then one can try gas scintillators for X-ray spectroscopic study.