Transcript Data Released by CMS - CMS DocDB Server

CMS Public Data for
High-School Analyses
Data Available
CMS “Masterclass” Tutorial
Resources
Dave Barney, CERN
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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
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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
Concentrate today on the Masterclass activity
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Data Released by CMS (2)
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Data Released by CMS (3)
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Data Released by CMS (4)
Used for Masterclass
measurements
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CMS Masterclass (1)
• Developed within the framework of IPPOG
International Masterclasses
http://www.physicsmasterclasses.org/
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CMS Masterclass (2)
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CMS Masterclass (3)
http://cms.web.cern.ch/content/cms-physics-masterclass
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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+  m+ + n
W+  e+ + n
W-  m- + n
W-  e- + n
Z0  e+ + eZ0  m+ + m-
To determine:
• W+/W- production ratio
(gain insight into the inner
structure of the proton)
• Z0 mass
• Using:
– iSpy-online event display software
– Google doc for counting, combining data etc.
MEASUREMENT IS 100% ONLINE! NO SOFTWARE DOWNLOAD!
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iSpy-online software
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Particle id in CMS
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
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e.g. W decaying to a
muon and a neutrino
Signature: Signal in muon detectors
+ missing energy
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e.g. Z0 decaying
to two muons
Signature: Two signals in muon detectors
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Measuring Charge
Clockwise bend = positive charge
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Data Analysis via shared
Google spreadsheet
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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
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Today’s Tutorial
– getting started
• Open your Firefox/Chrome/Safari browser with two
tabs:
1.
2.
Choose a “group” number between 1 and 19
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)
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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
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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
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+
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
W ® en
1.418 ± 0.008 stat ± 0.036 syst
W ® mn
1.423 ± 0.008 stat ± 0.036 syst
(combined)
0.5
1.421 ± 0.006 stat ± 0.033 syst
W ® ln
CMS
0
36 pb-1 at s = 7 TeV
NNLO, FEWZ+MSTW08 prediction
1.43 ± 0.04
1.5
[with PDF4LHC 68% CL uncertainty]
1
R+/- = [ s ´ B ](W + ) / [ s ´ B ](W - )
Dave Barney, CERN
What does this
mean?
That the “simple”
model of the proton
(uud) is not quite
correct……
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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”
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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 [email protected] 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.
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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/cgibin/PublicDocDB/ShowDocument?docid=11532
• Resources in French for CMS Masterclasses
https://cms-docdb.cern.ch/cgibin/PublicDocDB/ShowDocument?docid=11533
• Article about CMS Masterclasses
http://cms.web.cern.ch/news/being-physicist-day
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