Orientation

Welcome

Welcome to the very first workshop on the use of open data from the CMS experiment. We are really happy to have you here! In order to make the best use of the time during the workshop, we have prepared a set of pre-exercises, which you are requested to go through before the workshop.

Yes, requested: this is because we know that setting up the proper environment may take some time, and it may happen that you would need help. We can help you get started before the workshop, but during the workshop we really want to concentrate on the use of open data, and therefore we will do our best that everyone has all technicalities settled down in advance.

In this page, we try to explain why we have chosen those pre-exercises, please read though!

Analysis workflow

Analysis of CMS data is most commonly done in two steps

The first step will almost inevitably be done using the CMS software (CMSSW) and in a computing environment compatible with the open data.

For the computing environment, you can either

Setting up this environment is the first pre-exercise. The choice between these two options - VM or docker - depends on your own setup and your goals. We give a list a features which you can take into consideration when choosing between these two options at the end of this page.

Learning some basics of CMSSW is the second pre-exercise. We understand that not all of you are keen on learning the details of CMSSW, but some basic knowledge of it is definitely needed in order get hold of the data. Note that the code and commands to run are the same in VM and in docker.

In the second step, during this workshop, we will use root data analysis framework. This is because

Learning some basics of root useful for this workshop is the third pre-exercise. Note that if you do not wish to use root, you can use the analysis tools of your choice afterwards, but we will not be able to cover different options during this short workshop. This is why we ask you to go through some basic notions of root, even if you do not intend to use it later. And for those who are already familiar with root, take note that we will use some very nice new functionalities, such as root data frames, which you will be delighted to learn of!

The second, analysis step can be done in the CMS open data virtual environment (whether VM or docker) or by passing the output files to your local setup and analysing them there. If you are familiar with root and have it installed on your local system, you may prefer doing it there. In this case, check the root pre-exercise to be sure that you have the right root version used in the open data analysis example.

Different operating system

Traditionally, CMSSW is developed, validated and run in a well-defined version of linux operating system, which we have made available together with open data. Linux users will find their way through fairly smoothly, although they will need to use these old versions compatible with the data. Mac users have traditionally worked it through and it is quite common in use considering the amount of apples in some of our meetings (when we still used to sit in a common physical meeting room). For Windows, recently, there have been some quite interesting developments, mainly with docker and WSL, and we hope to bring through Windows users as well, without too many hiccups.

Please take note that this is a learning process for us as well, we really want to learn from the eventual difficulties you may encounter so that we can improve. However, bear with us, for the normal analysis work of CMS data we keep to those well-defined versions of linux, and we may not have all solutions for different environments ready.

VM or docker

Right at the start, for the first pre-exercise, you will need to decide if you want to go for VM or docker. Here we list some features which may help you in choosing between these two computing environments.

VM:

Docker:

Note that you can try both, if you wish. Windows WSL users may need to change a setting and reboot between switching from VM to docker