Hello,
Instead of TTree/TChain, I’d recommend you do this with RDataFrame:
which is a higher-level API.
Initially, you would create a new dataset from your collected data, a bit like it’s shown here:
So you would define how many events you want in your dataset, the columns of your dataset and then store that (snapshot) in a ROOT file. Note that you can use that ROOT file to create an RDataFrame too for later analysis (in the docs you can find everything you can do with RDataFrame).
Alternatively, in case you are currently storing the data you collect in a CSV file, you can load it directly from RDataFrame with the CSV data source:
One of the advantages of using RDataFrame is that you get parallelization on your local cores for free.
Please let us know if this model suits your use case and whether we can help you with anything else.
Enric