CMS Public Data for High-School Analyses

Data Available CMS “Masterclass” Tutorial

Resources

Dave Barney, CERN 1

Credits •  The use of CMS data for “Education & Outreach”

activities has been driven by: –  IPPOG – International Particle Physics Outreach Group

http://ippog.web.cern.ch/

–  QuarkNet – US network of HEP institutes and schools http://quarknet.fnal.gov/

–  I2U2 – Interactions In Understanding the Universe http://www.i2u2.org/

•  The data formatting and analysis tool development have mainly been done by Tom McCauley, Phong Nguyen, Mihael Hategan, Ken Cecire under the auspices of CMS and the groups above

Dave Barney, CERN 2

Data Released by CMS (1) •  Since 2010 CMS Collaboration has released small

samples of data for use by educators •  Roughly three categories:

–  Small data samples (hundreds to thousands of events) for high-school student activities in a limited time Mainly for “Masterclass” activities within IPPOG and QuarkNet

–  Medium data samples (hundreds of thousands of events) for high-school or science club activities over weeks or months Mainly within I2U2 framework

– Large data sample (50pb-1) for undergraduate students in workshops etc. (only one example so far: http://ippog.web.cern.ch/resources/2012/cms-hep-tutorial

Dave Barney, CERN 3 Concentrate today on the Masterclass activity

Data Released by CMS (2)

Dave Barney, CERN 4

Data Released by CMS (3)

Dave Barney, CERN 5

Data Released by CMS (4)

Dave Barney, CERN 6

Used for Masterclass measurements

CMS Masterclass (1) •  Developed within the framework of IPPOG

International Masterclasses http://www.physicsmasterclasses.org/

Dave Barney, CERN 7

CMS Masterclass (2)

Dave Barney, CERN 8

CMS Masterclass (3)

Dave Barney, CERN 9 http://cms.web.cern.ch/content/cms-physics-masterclass

CMS Masterclass (4) •  Particle identification in the CMS detector

–  Components of the detector –  Electrons and muons (positive & negative charge) –  Neutrinos, through missing ET

•  Analyse CMS data containing decays: –  W+ à µ+ + ν –  W+ à e+ + ν –  W- à µ- + ν –  W- à e- + ν –  Z0 à e+ + e-

–  Z0 à µ+ + µ-

•  Using: –  iSpy-online event display software –  Google doc for counting, combining data etc.

Dave Barney, CERN 10

To determine: •  W+/W- production ratio

(gain insight into the inner structure of the proton)

•  Z0 mass

MEASUREMENT IS 100% ONLINE! NO SOFTWARE DOWNLOAD!

iSpy-online software

Dave Barney, CERN 11

Particle id in CMS

Dave Barney, CERN 12

Muon (red track) traversing whole detector, leaving hits in outer layers. Missing energy represented by yellow arrow

Electron (yellow track) stopping in the ECAL. Missing energy represented by yellow arrow

e.g. W decaying to a muon and a neutrino

Dave Barney, CERN 13

Signature: Signal in muon detectors + missing energy

e.g. Z0 decaying to two muons

Dave Barney, CERN 14 Signature: Two signals in muon detectors

Measuring Charge

Dave Barney, CERN 15

Clockwise bend = positive charge

Data Analysis via shared Google spreadsheet

Dave Barney, CERN 16

Today’s Tutorial •  In a Masterclass situation we would now:

–  Ask the students to predict the expected W+/W- ratio from their knowledge of the quark structure of the proton – i.e 2

–  Show the students through a few events to understand a little more how to use the iSpy-online tool and see how to use the spreadsheet together

•  We would also split the students into groups of two – maximum 19 groups –  Separate data file (100 events) and separate spreadsheet

tab for each group

•  More than 19 people today doing the tutorial, so there may be some conflicts in the spreadsheet!

•  And we will concentrate on the W+/W- measurement Dave Barney, CERN 17

Today’s Tutorial – getting started

•  Open your Firefox/Chrome/Safari browser with two tabs: 1.  Choose a “group” number between 1 and 19 2.  Event display software

•  http://cern.ch/go/h9XN (same as http://www18.i2u2.org/elab/cms/event-display)

3.  Google Spreadsheet for results

•  http://cern.ch/go/KD7r •  Select the tab corresponding to your group number (1 to 19)

Dave Barney, CERN 18

Use iSpy-online to classify events etc. & spreadsheet to record findings

–  Click on the icon to see a transverse view –  Make sure the “Drift tubes (muon)” box is checked –  Click on the file folder icon to open the folder called

“mc” and then select “mc_n.ig” where “n” is the number of your group. Finally, select an event in the list and click the “load” button

–  Make sure the “Missing Et (reco)” box is checked –  Perhaps uncheck the “Tracks (reco)” box…. –  Rotate, zoom etc. to get an idea of whether you are

seeing signs of a Z0 or W+ or W- –  Follow the instructions in the spreadsheet –  To go to the next event, click the icon

Dave Barney, CERN 19

Ten minutes to “play”

•  With help in the audience from: – Stephanie Beauceron – Jean Fay – Tom McCauley

•  An “easy” event is: – File mc_1 – Event 109019570

Dave Barney, CERN 20

W+/W- Measurement •  “Results” tab on the spreadsheet shows the

combination of all student’s results –  Including an overall W+/W- ratio –  Can ask students why their measured ratio is not 2

Dave Barney, CERN 21 ) - B ](W× σ) / [ + B ](W× σ = [ +/-R

0 0.5 1 1.5

= 7 TeVs at -136 pbCMS

[with PDF4LHC 68% CL uncertainty]NNLO, FEWZ+MSTW08 prediction

0.04±1.43

ν e→W syst 0.036± stat 0.008±1.418

νµ →W syst 0.036± stat 0.008±1.423

(combined) ν l→W syst 0.033± stat 0.006±1.421

) - B ](W× σ) / [ + B ](W× σ = [ +/-R0 0.5 1 1.5

What does this mean? That the “simple” model of the proton (uud) is not quite correct……

Summary •  Data samples exist and are readily available on

the web •  Web-based tools (e.g. iSpy-online and Google

docs) enable simple data analyses to be performed at institutes or in schools

•  Feedback from students and teachers (and CMS physicists) is excellent

•  A “closure test” showed that students (from Annecy) correctly identified events/particles/charges with ~95% efficiency

•  Higgs events may be mixed-in to give the students an extra challenge – to “hunt the Higgs”

Dave Barney, CERN 22

We need you! •  Where can you do your own Masterclass-type

activities? –  In your institute –  In a local school equipped with PCs and internet

connection and Firefox/Chrome/Safari (a standalone dvd with data+iSpy is also available)

–  At CERN – investigating purchase of ~15 laptops for these activities

•  Please contact Marzena.Lapka@cern.ch if you: –  Wish to start your own educational activities based on

CMS data –  Have ideas for improvements, introductory talks,

suggestions for other analyses (and new data) etc.

Dave Barney, CERN 23

Resources •  CMS Education Web pages

http://cms.web.cern.ch/content/cms-data-public •  Example introductory presentations

http://cms.web.cern.ch/org/cms-presentations-public •  Resources in English for CMS Masterclasses

https://cms-docdb.cern.ch/cgi-bin/PublicDocDB/ShowDocument?docid=11532

•  Resources in French for CMS Masterclasses https://cms-docdb.cern.ch/cgi-bin/PublicDocDB/ShowDocument?docid=11533

•  Article about CMS Masterclasses http://cms.web.cern.ch/news/being-physicist-day

Dave Barney, CERN 24