Merge pull request #3 from cms-opendata-workshop/klp-initial-02

02: start with miniaod info

episodes/02-nanoaod-miniaod.md

@@ -1,38 +1,70 @@
 ---
 title: "Differences between NanoAOD and MiniAOD"
 teaching: 10
-exercises: 0
+exercises: 5
 ---
 
 :::::::::::::::::::::::::::::::::::::: questions 
 
-- What have we learned in the pre-exercises and how can we apply it?
-- What is the structure and content of the nanoAOD format?
-- How is it different from miniAOD?
+- What is the structure and content of the NanoAOD format?
+- How is it different from MiniAOD?
+- What if the required information is not available in the NanoAOD format?
 
 ::::::::::::::::::::::::::::::::::::::::::::::::
 
 ::::::::::::::::::::::::::::::::::::: objectives
 
-- Apply what we have learned in the pre-exercises
-- Learn about the structure and content of nanoAOD and how it differs from miniAOD
+- Learn about the structure and content of NanoAOD and how it differs from MiniAOD
+- Learn where to find information on how to use MiniAOD
 
 ::::::::::::::::::::::::::::::::::::::::::::::::
 
+## What are the differences between NanoAOD and MiniAOD
 
-TO-DO we can "borrow" information from below:
+In the previous episode, we found the description of the NanoAOD variables.
+
+Let us now compare it to the MiniAOD format. Note that the variable descriptions are not available attached to the datasets, but we can have a look at the [MiniAOD description in the CMS WorkBook](https://twiki.cern.ch/twiki/bin/view/CMSPublic/WorkBookMiniAOD2016#High_level_physics_objects).
+
+You will see a table starting with:
+
+![](fig/MiniAODTable.png){alt='MiniAOD descripion in the CMS WorkBook'}
+
+The objects in the MiniAOD format are C++ classes in CMSSW, the CMS Software package, and the table gives the class name. We can find the exact class description in the CMSSW reference manual. See, for example 
+
+- [`pat::Muon`](https://cmsdoxygen.web.cern.ch/cmsdoxygen/CMSSW_10_6_25/doc/html/d6/d13/classpat_1_1Muon.html) 
+- [`pat::Electron`](https://cmsdoxygen.web.cern.ch/cmsdoxygen/CMSSW_10_6_25/doc/html/d2/d1f/classpat_1_1Electron.html).
+
+These are C++ classes that can *inherit* information from parent classes or contain objects, of some complex types. Therefore, some of the variables are not explicitly listed as they are available through other objects.
+
+For example, for MiniAOD, we will not find `eta` or `pt` explicitly in the class description as they can be obtained through the `LorentzVector` object. This is transparent in the code when accessing those values, but much less so in the documentation!
+
+Let us now compare it to NanoAOD. The major difference is that MiniAOD contains most of the constituents of a physics object (such as tracks and/or calorimeter clusters) whereas NanoAOD only contains some information about them.
+
+## NanoAOD with particle flow candidates
+
+Many CMS open data users have relied on the [Particle flow information](https://twiki.cern.ch/twiki/bin/view/CMSPublic/WorkBookMiniAOD2016#Packed_ParticleFlow_Candidates), available in the MiniAOD format but not in the NanoAOD format. See the class description: [`pat::Packe](https://cmsdoxygen.web.cern.ch/cmsdoxygen/CMSSW_10_6_25/doc/html/d8/d79/classpat_1_1PackedCandidate.html).
+
+TO-DO
+find them and compare variable lists 
+
+
+## Using MiniAOD
+
+Demo only, 
+
+show container
+
+show edmDumpEventContent
+
+miniAOD links for use: [Getting started with miniAOD](https://opendata.cern.ch/docs/cms-getting-started-miniaod)
 
-miniAOD links for use: [Getting started with miniAOD](https://opendata.cern.ch/docs/cms-getting-started-miniaod), [miniAOD in Workbook](https://twiki.cern.ch/twiki/bin/view/CMSPublic/WorkBookMiniAOD2016#High_level_physics_objects)
 
-nanoAOD links for use: [Getting started with nanoAOD](https://opendata.cern.ch/docs/cms-getting-started-nanoaod)
 
 ::::::::::::::::::::::::::::::::::::: keypoints 
 
-- Use `.md` files for episodes when you want static content
-- Use `.Rmd` files for episodes when you need to generate output
-- Run `sandpaper::check_lesson()` to identify any issues with your lesson
-- Run `sandpaper::build_lesson()` to preview your lesson locally
+- Analyses that require detailed information about physics object constituents may require using MiniAOD instead of NanoAOD
+- Selected datasets include Particle flow candidates in an enriched NanoAOD format are available and their use does not require using CMS-specific software
+- CMSSW environment is available as a Docker container and can be used to work with MiniAOD
 
-::::::::::::::::::::::::::::::::::::::::::::::::
 
-[r-markdown]: https://rmarkdown.rstudio.com/
+::::::::::::::::::::::::::::::::::::::::::::::::