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Nuclear Physics B Proceedings Supplement 00 (2014) 1–6

Nuclear Physics BProceedingsSupplement

How the HYPATIA analysis tool is used as a hands-on experience to introduceHEP to high schools

Christine Kourkoumelis and Stylianos Vourakison behalf of the ATLAS collaboration1

Physics Faculty and Institute of Accelerating Systems and Applications,University of Athens, Panepistimioupoli, Ilissia 15771, Greece

Abstract

“HYPATIA” is a tool for interactive analysis of data from the ATLAS experiment at the Large Hadron Collider ofCERN. It has been created by the authors and has been evolving over a number of years. It is available in a dowloadableversion, which is regularly used in the International Masterclasses, and an online version which now exists in the formof a webapp. Furthermore, the data from ATLAS, which are necessary for performing different educational analysispaths, are available online. Such examples of interactive analyses vary from the estimation of the magnetic field ofthe ATLAS solenoid magnet, to detecting “pseudo” Higgs events. These applications have been used in recent yearsin a large number of schools in the form of a half-day mini local (or even remote) masterclass. These activities havebeen supported by various European Union outreach programs which give emphasis to promoting science educationin schools through new methods based on the inquiry based techniques: questions, search and answers. This waywe have been able to introduce cutting edge research in particle physics to High Schools, bridging the gap betweenresearch and school hands-on experience.

Keywords: ATLAS, LHC, HYPATIA, ATLAS event analysis tool

1. INTRODUCTION1

Particle physics has rarely (if ever) been part of the2

high-schools curricula in most countries. The same3

is true to some degree about the ideas of modern4

physics in general. School curricula in most countries5

include only the basic physics concepts that have been6

known for centuries. The demonstrations/experiments7

available date back to the beginning of the 20th century.8

Moreover, no information is given about the modern9

research and the cutting-edge technologies. The10

European Union (EU) has long recognized the need of11

bridging the gap between school science education and12

pioneering research. Through the support of several13

1Email: [email protected] and [email protected]

EU outreach programs, the HYPATIA event tool [1]14

has been developed and implemented in several inquiry15

based education contexts. HYPATIA is an innovative16

hands-on event visualization tool which aims to intro-17

duce the students to the most modern particle physics18

research. It aims to stimulate students’ interest with19

science by involving them to interactive analysis of data20

from the ATLAS experiment [2] at CERN.21

22

The recent discovery of the Higgs boson has attracted23

large media coverage generating great public interest.24

The students, through the usage of HYPATIA, can try25

to “discover” the Higgs boson themselves. In addi-26

tion, their teachers get extensive help in their effort to27

explain the most recent experimental results, subjects28

which they have not been trained to explain. In this29

C.Kourkoumelis and S.Vourakis / Nuclear Physics B Proceedings Supplement 00 (2014) 1–6 2

way both students and teachers get engaged with playful30

learning of High Energy Physics (HEP).31

2. THE EU OUTREACH PROJECTS WHICH32

HELPED DEVELOP THE HYPATIA TOOL33

As mentioned in the introduction HY.P.A.T.I.A (HY-34

brid Pupils Analysis Tool for Interactions in ATLAS) is35

an event display for data collected by the ATLAS exper-36

iment at CERN. It has been developed at the University37

of Athens since 2007, in cooperation with the Belgrade38

Institute of Physics during the first years (2007-2010).39

The development was initially supported by the ATLAS40

outreach group, and subsequently by the following EU41

outreach projects:42

1) Learning with ATLAS@CERN (2009-2011) [3].43

This project was coordinated by one of the authors44

(C.K); its main objective was to use the information ma-45

terial and the data from the ATLAS experiment in order46

to build educational scenarios for schools and universi-47

ties. It formed a rich repository of HEP resources rele-48

vant to the ATLAS experiment [4]. This way it demon-49

strated and applied the innovative pedagogical approach50

of inquiry learning to communities of students, teachers51

and the general public.52

2) PATHWAY to inquiry based science education53

(2011-2013). The project focused on teachers and pro-54

posed a standard-based approach to teaching science,55

in general and not only HEP, by inquiry. It outlined56

instructional models, motivated the teachers to adopt57

inquiry based techniques and activities in their class-58

rooms, and offered access to a unique collection of open59

educational resources and teaching practices [5].60

3) Discover the COSMOS: e-Infrastructures for an61

Engaging Science Classroom (2010-2012) which was62

coordinated by one of the authors (C.K). The Discover63

the COSMOS activities introduced students to concepts64

and ideas of big science in the fields of Astronomy65

and HEP. During its two year course, it implemented66

a great number of activities that interconnected schools67

and research centers following a detailed pedagogical68

framework. The project developed an innovative learn-69

ing environment [6] which brings together more than70

95,000 science education learning objects and activi-71

ties connected to the science curriculum from Astron-72

omy, Space Physics and HEP. The consortium managed73

to mobilize an extremely large number of users (5,70074

teachers and approximately 31,000 students) and to in-75

volve them in numerous activities, at schools and at re-76

search centers.77

4) Go-lab [7]: Online science labs, started in Novem-78

ber 2012 for a four year duration. It goal is to open79

up the remote science laboratories, their data archives,80

and virtual models (“online labs” ) for large-scale use81

in education. Go-lab is addressed to students, teach-82

ers and lab-owners. During its first year of operation it83

has already created a pilot federation of several online84

labs from worldwide renowned research organizations85

(e.g., CERN, ESA) and from several selected universi-86

ties. Four HYPATIA scenarios which will be described87

in sections 4 and 5 are included in the Go-lab portal as88

Inquiry Learning Spaces (ILSs). The structure of each89

ILS is such that it includes all steps of the inquiry learn-90

ing methodology, namely : orientation, conceptualiza-91

tion, investigation, conclusion and discussion.92

5) Inspiring Science Education (ISE). The ISE93

project [8] began in April 2013 and will last till July94

2017. It aims at contributing to the implementation95

of the “Digital Agenda for Europe” in particular con-96

tribute to mainstreaming the eLearning for moderniza-97

tion of education and training. The ISE designs, plans98

and implements large-scale pilots to stimulate and eval-99

uate innovative use of existing eLearning tools and dig-100

ital resources for scientific disciplines and technology101

(STEM related subjects), enhancing science learning102

in 5,000 primary and secondary schools in 15 Euro-103

pean Countries. During its first year it has already104

reached 500 schools in Europe; all Greek schools par-105

ticipating in the pilot phase have received training in the106

HYPATIA HEP scenarios through mini-masterclasses107

(see 6.2).108

3. DESCRIPTION OF THE HYPATIA TOOL109

The full-featured offline version is based on the AT-110

LANTIS event display created by the University Col-111

lege London and Birmingham University teams of AT-112

LAS [9]. HYPATIA (Figure 1) offers a graphical repre-113

sentation of the products of proton collisions registered114

by the ATLAS detector. Students using the event dis-115

play can interact with the events and in this way study116

the fundamental building blocks of nature and their in-117

teractions. At the same time, they learn how the gigantic118

state-of-the-art detector works. This gives students an119

insight into the research being done at CERN and stim-120

ulates an enthusiastic interest in it and in possible sci-121

entific careers. The full version of HYPATIA has been122

used in the International Masterclasses (IMC) [10], [11]123

(see 6.1) unofficially since 2007 in Athens and officially124

since 2009 worldwide. It uses java and is therefore com-125

patible with most operating systems (Windows, Linux,126

OSX, Solaris). This version is updated every year with127

new functionality to better serve the IMC’ s needs as one128

of the two ATLAS exercises -the Z path [12]- evolves.129


Figure 1: Offline version used in the International Masterclasses

The latest additions include the use of photons in or-130

der to study the H → γγ decays along with the cor-131

responding histograms and export functions for the re-132

sults. In the most recent HYPATIA-v7.4 2014 Mas-133

terclass version, the histograms of the decay products134

of H → ZZ → 4`, (` = e, µ) are plotted separately135

according to the type of lepton combination, namely136

4` = 2e2µ, 4µ, 4e). The offline version of HYPATIA is137

freely available at [13] along with event files, instruc-138

tions and supporting material. This version has also139

been used in the context of Nuclear Physics laboratory140

for 4th year undergraduate students at the University of141

Athens.142

In addition to the offline version, since 2010 the Uni-143

versity of Athens has developed an online version of144

HYPATIA [14] which is simpler to handle events and145

aimed squarely at educational use. The first iteration146

of the online version was implemented as a java applet147

and was used from 2010 until 2013. Due to the java148

requirement which limited the target use (not supported149

by mobile operating systems) and the increasing diffi-150

culty in supporting java in recent browser versions due151

to security concerns, a new iteration was developed in152

2014. This is implemented as a web application and is153

based on HTML5 and javascript which are supported by154

all operating systems, both pc based (windows, linux,155

etc) and mobile (android, ios, windows phone). In ad-156

dition, the new iteration does not require the installation157

of any additional software (such as java) and runs every-158

where out of the box. The web application is designed to159

be simpler to use than the offline version of HYPATIA,160

while still containing all the functionality necessary for161

the exercises. It is especially easy to explain to students,162

doesnt need any deployment in classrooms or computer163

laboratories and can be used in any device available,164

even tablets and smartphones. The web application (on-165

line) version of HYPATIA shown on Figure 2 is avail-166

able at [14] and includes event files for all exercises (Z,167

Higgs, Conservation of momentum and Magnetic field168

measurement), instructions (including videos), help, ex-169

ercise descriptions and solutions. Both the application170

and the supporting website are available in Greek, En-171

glish, German and French. The great advantage of the

Figure 2: New online version of HYPATIA written in Javascript andHTML5

172

web application is its flexibility and possibility of cre-173

ation of personalized exercises/labs by the instructor. It174

includes four different versions with increasing level of175

difficulty; level four (HYPATIA4) being the full version176

which permits the reconstruction and histogramming of177

the Z and Higgs bosons.178

4. HEP SCENARIOS OF HYPATIA179

As mentioned above, the Go-lab portal already in-180

cludes two full ILSs dedicated to the discovery of the181

Z0 [15] and Higgs boson [16] respectively. By following182

the ILSs step-by-step instructions are given to students183

and teachers, so that the scenarios can be performed in184

class without external help. A search for the Z0 and185

Higgs boson can also be performed using HYPATIA4186

online, but in this case the help of a HEP scientist (ei-187

ther visiting or remote) is necessary. The same is true188

for the offline version of HYPATIA, where the Z path189

instructions [12] have to be followed with external help.190

In the Z boson exercise the students study the Z0 →191

e−e+ and Z0 → µ−µ+ decays. They are guided to learn192

how to separate the characteristic signatures which the193

muons or the electrons leave in the ATLAS detector194


by studying the event display in two mutually perpen-195

dicular views. After the identification of two opposite196

charged muons or electrons, the corresponding tracks197

are inserted into the invariant mass table and their invari-198

ant mass is automatically calculated. By studying the199

invariant mass histogram, mll, the user is instructed to200

determine whether she/he has found a “resonance” cor-201

responding to the mass of the Z0 boson, and in this202

way infer its existence. The histograms of the invariant203

masses of Z0 → 2e and Z0 → 2µ (mee and mµµ his-204

tograms) are also available, so the user can compare the205

two masses and their differences, if any. The user should206

also observe the finite width of the resonance and draw207

conclusions about the lifetime of the boson and the ex-208

perimental errors.209

The Higgs exercise builds upon the experience gained210

during the “Discover the Z boson” exercise. This time211

the students look at Higgs boson decays into four lep-212

tons (H → 4l) which can be two pairs of electron-213

positron or muon-antimuon or one of each. The user214

looks for two Z bosons in the event and inserts the de-215

cay products of each one into the invariant mass table.216

This way she/he can determine the mass and width of217

the Higgs boson2 through the corresponding mllll his-218

togram.219

5. THE HYPATIA SCENARIOS DIRECTLY220

CONNECTED TO THE SCHOOL CURRIC-221

ULA222

The Go-lab portal also contains two new scenarios di-223

rectly connected with the school curricula: these exer-224

cises have short duration, are aimed at younger students225

and can be easily implemented in the classroom in the226

course of one lesson plan.227

The first exercise, aims to demonstrate that the con-228

servation principles [17] apply to big science as well,229

namely from the macroscopic to the microscopic world.230

The cross-section of the ATLAS detector perpendicular231

to the proton beams (z-axis) is used to demonstrate the232

principle, since both before and after the collision, the233

total momentum is zero. In this exercise we use spe-234

cially selected and filtered events with very few charged235

tracks (muons, which are easily identifiable). The stu-236

dents should add up all momenta of the tracks either by237

vector addition or by adding the x,y components. The238

2The events contained in the “Higgs” online file are not real datafrom ATLAS but are “pseudo” events produced by overlapping tworeal Z events, therefore the mass of the few “Higgs” events comes outclose to 2mZ .

kinematic quantities of each track (direction, momen-239

tum) are given in the table shown in the lower left hand240

side of Figure 2. Then by calculating the vector oppo-241

site to the sum of the momenta of all particles, the stu-242

dents either confirm that it is almost zero (experimen-243

tal errors always exist in real data) or that a substantial244

amount of momentum is missing in a particular direc-245

tion. This may be an indication of an invisible neutrino.246

They can also compare the result of their calculation247

with the corresponding quantity calculated by the web248

app ETmiss and the direction of the resulting vector (in249

the x-y plane) to the red dotted line shown on the can-250

vas which is the corresponding quantity calculated by251

the webapp.252

The philosophy behind the second exercise [18] is to253

apply the Lorentz law of the force exerted on a particle254

by the magnetic field in order to calculate the strength of255

the magnetic field of the ATLAS solenoid surrounding256

the Inner Detector [2]. ATLAS measures the momen-257

tum of charged particles by bending them in the mag-258

netic field of its several magnets. The inner magnet is259

a superconducting solenoid creating an almost uniform260

field of 2 Tesla. The magnetic field lines are parallel261

to the beams, thus the tracks of the charged particles262

are bent by the Lorentz force in the x-y plane (trans-263

verse plane, plane of Figure 2). The force exerted in264

this plane is the centripetal force which is equal to the265

Lorentz force:266

(m ∗ v2T )/R = q ∗ vT ∗ B (1)267

where vT is the velocity of the charged particle calculate268

in the plane transverse to the colliding beams269

Taking as known the strength of the magnetic field in270

Tesla, the absolute value of the charge q and estimating271

the radius of curvature of the tracks R in meters, AT-272

LAS calculates the pT (the transverse component of the273

momentum) of the charged tracks:274

pT (GeV/c) = 0.3 ∗ R(m) ∗ B(T ) (2)275

In the exercise the user treats the pT as known (by276

selecting a track and looking at its value in the table277

shown in the lower left hand side of Figure 2. The R278

(arc radius) is calculated by HYPATIA by right clicking279

on three well separated points on the curved track and280

fitting a circle to it3. The result obtained by the user is281

the strength of the field in Tesla, since HYPATIA soft-282

ware solves equation (2) for B. After performing this283

3In order to have tracks which are bent within the 2.4 m diameterof the solenoid only charged tracks with transverse momenta between500-700 MeV/c appear in the list of tracks of this exercise.


calculation for a small number of tracks, the user ob-284

tains the mean value of B and the instructor can pursue285

a discussion of statistics, outliers etc.286

6. ACTIVITIES FOR IMPLEMENTATION OF287

HYPATIA IN THE SCHOOL CLASS288

Since 2007 when the first of the five European289

projects was launched and the first offline version290

of HYPATIA was written, outreach teams from the291

consortium, the participating countries and beyond292

have been using HYPATIA in the context of master-293

classes, e-Masterclasses and mini-masterclasses. Sum-294

mer schools, teachers’s training sessions and contests295

have also been organized in the framework of the above296

mentioned EC projects to effectively support and dis-297

seminate the widespread use of the proposed activities298

in the participating countries and beyond (i.e. Australia,299

Canada, Bulgaria, U.S.A. etc).300

6.1. International Masterclasses301

The IMC organized each March by the International302

Particle Physics Outreach Group (IPPOG) [19] provide303

an opportunity for high school students and their teach-304

ers to be “scientists for a day”. Their goal is to famil-305

iarize the teachers and students with the cutting-edge306

research performed at CERN and in the LHC in partic-307

ular. Each year about 10,000 high school students from308

41 countries all over the world go to one of about 150309

nearby universities or research centres for one day in310

order to unravel the mysteries of particle physics by an-311

alyzing real data.312

During the day-long activity the local organizers313

(HEP scientists from universities or research centres)314

explain the ideas of particle physics and its importance315

in basic research while demonstrating the fundamentals316

of particle detector operation and explaining the way317

particles interact and leave characteristic signatures in318

the detectors according to their type.319

HYPATIA is used in the ATLAS Z path activity [12]320

of the IMC’ s. This is the most popular exercise used by321

67 institutes worldwide in 2014. The students use the322

HYPATIA offline tool and real events from the ATLAS323

detector in order to identify and study decays of short-324

lived particles such as Z0 → 2l, J/ψ → 2l, Y → 2l,325

H → 4l and H → 2γ decays. After the end of the326

event analysis, the students compare their results with327

those of students from about 5-6 other institutes which328

performed the same analysis, during a videoconference.329

6.2. Mini Masterclasses and e-Masterclasses330

The mini-masterclasses and e-masterclasses were pi-331

oneered by the Discover the COSMOS project and are332

smaller scale half-day masterclasses where the students333

can stay in their own school (or go to CERN) and334

are guided either remotely (by video-conferencing) or335

by a few visiting scientists with the simultaneous help336

from their trained teachers. For these masterclasses the337

students use the web application version of HYPATIA338

which allows easy use in any internet enabled device339

without the need for deployment. Usually these master-340

classes are accompanied by a virtual visit to the ATLAS341

control room. This way the students have the opportu-342

nity to see the scientists at work doing their shifts and343

discuss with them in a long question and answer ses-344

sion, following the presentation of the mini-experiment.345

Figure 3 shows a map of the very recent masterclasses346

performed in Greece during the last two years, which347

covered almost all regions of the country by visiting348

about 50 schools. Similar events were also performed

Figure 3: Mini masterclasses in Greece

349

in other European countries as well as at CERN, where350

students from four different countries came together for351

such events. Moreover, during the 2013 CERN Open352

Days, a large crowd of about 3,000 visitors came to the353

ATLAS stand and had hands on experience with the on-354

line HYPATIA tool as well as with MINERVA (Mas-355

terclass INvolving Event Recognition Visualised with356

Atlantis), Collider, LHC game and CERNland.357


6.3. HYPATIA Teachers training during CERN exposi-358

tions359

In addition to summer schools a large number of HY-360

PATIA training workshops were organized during the361

visits of the CERN mini exposition in Greece as well as362

in Spain and Cyprus. The mini expo, for its 2011-2012363

tour, was upgraded with new posters, hands-on activities364

and combined with educational activities. In every one365

of its six stops in different Greek cities (Athens, Herak-366

lion, Patras, Alexandroupolis, Kavala and Volos) several367

local teacher workshops were organized, training more368

than 650 teachers.369

In the spring of 2014 the “Accelerating Sci-370

ence” CERN exposition came to Athens for a month.371

It was hosted at the premises of the Eugenideio Foun-372

dation (science museum and planetarium). The exhi-373

bition was a huge success with more than 11,000 visi-374

tors, among them 4,000 students from 92 schools. Also375

about 120 teachers were trained in the use of HYPATIA376

in three workshops held in parallel with the exhibition.377

7. Conclusions378

During the past two years a great effort has been379

made to exploit the recent publicity about CERN and380

the Higgs boson, in Greece and in Europe. The Inter-381

national Masterclasses, the mini Masterclasses and the382

two CERN exhibitions have helped thousands of people,383

ranging from the general public to students and their384

teachers to get acquainted with HEP and CERN. The385

number of European schools visiting CERN has risen386

significantly. More specifically the number of Greek387

schools visiting CERN during the past two years has388

increased by 23% from 2012 to 2013 and a further 31%389

from 2013 to 2014. CERN can no longer accommo-390

date them! Furthermore, an example of the impact that391

all those actions have had on Greek students and teach-392

ers, is the fact that Odysseus’ Comrades team from Var-393

vakios Pilot School in Athens were joint winners of394

the Beam line competition of CERN. The teacher who395

led the team, A. Valadakis, has been trained in the use396

of HYPATIA and participated with his students at sev-397

eral masterclasses. He has also brought his students at398

CERN several times. This is a great example of the im-399

pact of such actions extending beyond the classroom400

and the given exercises. It shows that under the right401

circumstances, students and teachers can build upon the402

knowledge they gain through those actions and eventu-403

ally construct their own exercises or experiments.404

8. Acknowledgments405

This research has been co-financed by the European406

Union (European Social Fund - ESF) and Greek na-407

tional funds through the Operational Program “Educa-408

tion and Lifelong Learning ” of the National Strate-409

gic Reference Framework (NSRF) - Research Fund-410

ing Program: THALES. Investing in knowledge society411

through the European Social Fund.412

References

[1] C. Kourkoumelis and S. Vourakis, “HYPATIA-an online toolfor ATLAS event visualization ” , Phys. Educ. 49, 21 (2014).

[2] ATLAS collaboration, “The ATLAS Experiment at the CERNLHC”, JINST 3, S08003(2008).

[3] R.M.Barnett et al, “Learning with ATLAS experiment atCERN” , Phys. Educ. 47, 28 (2012).

[4] http://www.learningwithATLAS-portal.eu.

[5] http://www.pathway-project.eu

[6] http://www.portal.discoverthecosmos.eu.

[7] http://www.go-lab-project.eu/frontpage.

[8] http://inspiring-science-education.eu.

[9] http://atlantis.web.cern.ch/atlantis

[10] http://physicsmasterclasses.org.

[11] E. Johansson et. al., “European Particle physics masterclassesmake students into scientists for a day” , Phys. Educ. 42, 636(2007).

[12] http://atlas.physicsmasterclasses.org/en/zpath.htm.

[13] http:/hypatia.phys.uoa.gr.

[14] http://hypatia.iasa.gr.

[15] https://graasp.epfl.ch/#item=space9249.




[19] http://ippog.web.cern.ch.

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