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howto:t3r_antibunching_-_slow_decay [2015/06/03 15:07] adminhowto:t3r_antibunching_-_slow_decay [2022/02/01 11:32] (current) – [A decay caused by correlation statistics] peter
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-{{tag> antibunching T2}}+{{tag> antibunching T3-mode T2-mode}} 
 +~~TOC~~ 
 +====== Artefacts in Antibunching Histograms - Slow Decay ======
  
-====== T3R Antibunching - Slow Decay ====== 
  
-===== Q.: How can we avoid decay at very long time delay (up to 5us)? ===== 
-==== In this show-case the external preconditions are: ==== 
  
-- detectors: perkin elmer SPCMAQR14 
  
-- 700 nm SP filter in front of one of the APDs 
- 
-- sample: diamond nanocrystals (100 nm), we are measuring the antibunching of the NV centers emission 
- 
-- laser wavelength: 532 nm, cw 
- 
-- T3R Measurement with PicoHarp Software  
- 
-===== A.: The decay can be caused by blinking of the nanodiamonds. ===== 
 ==== A decay caused by correlation statistics ==== ==== A decay caused by correlation statistics ====
  
-On top of an eventual blinking you will have a decay caused by correlation statistics.+[{{howto:slope.png ?478x300|Fig. 1: Baseline decay }}]
  
-This happens because you correlate the first arriving photon against a photon at the longer time,+This decay is caused by correlation statistics. This happens because you correlate the first arriving photon against a photon at the longer time, which will be an increasingly unlikely event because the earliest stop photons always win and the experiment restarts.
  
-which will be an increasingly unlikely event because the earliest stop photons always win and the experiment restarts.+A simulation with 90ns dead-time period: 
  
-I attached a simulation+[{{howto:logf.png?320x240|Fig. 2: Simulation }}]
  
-[{{howto:logf.png?320x240|Fig. 1: Logfile logf.png }}] 
  
  
  
- +\\
-\\ ==== You will I need the raw data ==== +
 The timescale is in ns. The plateau is the [[glossary:dead time]]. The decay slope depends on the count rate. The timescale is in ns. The plateau is the [[glossary:dead time]]. The decay slope depends on the count rate.
  
-You can zoom into your data and you will see roughly the same behavior - linear decay after the [[glossary:dead time]], which than of course is overshadowed by the background. +The way to avoid this is to calculate the total correlation after T2 MODE MEASUREMENT. This is not a start-stop correlation but the correlation of every photon against every photon.
- +
- +
-The way to avoid this is is to calculate the total correlation. This is not a start-stop correlation but the correlation of every photon against every photon+
- +
-It can be done measuring in T2 mode and then correlating using the SymPhoTime Software (http://www.picoquant.com/products/sw_mt/sw_mt.htm).+
  
-For a trial you will I need the raw data - a pt2 file containing all the photon data - not just the correlated curve. You can record this using the button I highlighted in the attached screenshot+It can be done using the SymPhoTime Software (http://www.picoquant.com/products/sw_mt/sw_mt.htm).
  
howto/t3r_antibunching_-_slow_decay.1433344033.txt.gz · Last modified: 2015/06/03 15:07 by admin