J. Stefan Institute, Ljubljanahttp://www-f9.ijs.si

Institute:Multidisciplinary institute, largest research institution in Slovenia•Physics (solid state, particle physics, nuclear physics, theory, surface science, reactor physics)•Chemistry•Biochemistry•Electronics, electrotechnics

Staff: about 1000

Main facilities: •TRIGA MarkIII reactor •Tandem 2 MeV

Peter Križan, UL+JSI

JSI: interdisciplinary research is

easy – next door lab might have a

solution for your troubles

Example: High power pulsed laser

in the solid state department (80fs

pulse width, 10J/pulse)

excellent for Single Event Upset

(EPS) tests of read-out electronics

for Belle SVD

Experiments: ATLAS, Belle, AUGER Past: HERA-B, CPLEAR, DELPHI

Staff: Researchers: ~20 (including part time professors of the

Universities of Ljubljana and Maribor) PhD students: ~10

Particle physics department (F9)

Physics Panel, 17/06/20084

Research Programme – Snapshot

R&D projects

• Cryogenic detectors (CERN RD-39)

• Diamond detectors (RD-42)

• Radiation hard detectors (RD-50)

ATLAS experiment at LHC in CERN~2000 researchers, 167 institutions

Belle experiment at KEK-B in KEK~380 researchers, 55 institutions

EU projects Grid computing (EGEE-I, II, III)

Medical imaging detectors (MADEIRA)

MC training on particle detectors

(MCPAD)

RADFET dosimetry (RADOS)

Physics Panel, 17/06/2008

Experimental Paricle Physics 5

Decays to CP eigenstates

difference of effective lifetimes measured in

decays to CP (D0 → K+K-, +-) and non-CP states (D0 → K-+)

precise measurement first evidence of mixing

(30 years after D0 discovery)

+

)%25.032.031.1( CPy

yKK

Ky

CPVnoCP

1)(

)(

Belle, Phys. Rev. Lett. 98, 211803 (2007)

ratio

(K+K-++-) vs. K-+

y: one of parameters determining the rate of mixing

Highlights - D0 Meson Mixing

Expertise(in experimental methodology)

• RICH detectors: DELPHI, HERA-B, Belle upgrade• Si strip detectors: DELPHI, RD20, ATLAS, Belle• Diamond sensors: ATLAS BCM, Belle radiation monitoring• readout/ trigger electronics: HERA-B (RICH, tracker), Belle

(SVD, PID upgrade) • Grid computing: CrossGrid (EU project), BalticGrid

(EU project), WLCG• Monte Carlo simulations (detector modelling, physics

simulations)• Lecturing at the University of Ljubljana (undergraduate and

postgraduate courses): particle physics, detector techniques, analysis methods; supervising diploma, MSc and PhD theses.

7

JSI@ATLASATLAS

– Members since 1996– SemiConductor Tracker

• Radiation hardness studies and QA (at the reactor center)

• Low-mass tapes and thermal enclosure heaters

– Beam Conditions Monitor– Radiation monitors– Physics analysis and MC software– Grid computing – TIER-2 centre

8

Into the Future – R&D for sLHC

• sLHC = LHC x 10 in luminosity– Severe radiation damage to tracker– Current tracker needs to be replaced– All-Si tracker envisaged– Si (short) strips at outer radii– Pixels inside

• Active in two ATLAS R&D projects– Diamond pixels– n+p strips– Recent striking result

Collected charge from n+p strips independent of fluence if sufficiently high bias applied

HERA-B RICH

100 m3 of C4F10 ~1 ton of gas

HERA-B RICH Little noise, ~30 photons per ring

Typical event

Worked very well!

Kaon efficiency and pion, proton fake probability

KK

pKK

Belle PID upgrade R+D

Two new particle ID devices, both RICHes:

Barrel: TOP – a special kind of DIRC

Endcap: proximity focusing RICH

stack two tiles with different refractive indices: “focusing” configuration

How to increase the number of photons without degrading the resolution?

normal

Radiator with multiple refractive indices

n1< n2

focusing radiator

n1= n2

4cm aerogel single index

2+2cm aerogel

Focusing configuration – data

NIM A548 (2005) 383

JSI is looking forward to the collaboration

within the MC-PAD project

Physics Panel, 17/06/2008

Experimental Paricle Physics 15

Highlights - Direct CP Violation

Belle, Nature 452, 332 (2008)

Difference between B and B decays CP violation known; magnitude too small

to describe matter domination in universe

within SM AK+- ≈ AK+0 008.0018.0094.0 KA

01.003.007.00 KA

)()(

)()(0 fBNfBN

fBNfBNf

A

~ one out of 105 B mesons

decays to this final states

037.0164.0 A

difficult to explain within SM

(especially in combination with other meas.);

hint for yet unknown sources of CP violation?