Astroparticle Physics at the Royal Institute of Technology

1. Presented by Felix Ryde Astroparticle Physics at the Royal Institute of Technology Faculty: Professor Mark Pearce Docent Felix Ryde Post Doc: Announcement for GLAST (see www.particle.kth.se/astro) Graduate Students: Cecilia Marini Bettolo (PoGOLite) Petter Hofverberg (PAMELA) Mózsi Kiss (PoGOLite) Laura Rossetto (PAMELA) Juan Wu (PAMELA)

2. Astroparticle Physics at KTH • Research on the high-energy Universe through the study of X- and • gamma-radiation and cosmic rays. The group has actively participated in • experiments measuring different aspects of the cosmic radiation for more • than a decade. • The fundamental scientific questions addressed concern particle acceleration • and radiation processes in cosmic plasmas, in the galaxy and around compact • objects, and the understanding of dark matter and gamma-ray bursts. • The focus is on design and development of strategic satellite- and balloon- • borne instrumentation, and on the analysis and astrophysical interpretation • of the data obtained with these instruments.

3. Astroparticle Physics at KTH • PAMELA: Payload for Antimatter Matter Exploration and • Light-nuclei Astrophysics. • PoGOLite: Polarised Gamma-ray Observer. • GLAST: Gamma-ray Larger Area Telescope • Outreach: (SEASA)

4. PAMELAPayload for Antimatter/Matter Exploration and Light-nuclei Astrophysics

5. Precision study of charged particles in the cosmic radiation (antiprotons and positrons) • Search for dark matter • Search for antihelium (primoridal antimatter) • Study of cosmic-ray propagation (light nuclei and isotopes) • Study of electron spectrum (local sources?) • Study solar physics and solar modulation • Study terrestrial magnetosphere

6. EM shower containment Magnetic curvature(trigger) Design performance Maximum Detectable Rigidity (MDR) ‘Spillover’ • Energy rangeParticles/3 years • Antiproton flux 80 MeV - 190 GeV >3x104 • Positron flux 50 MeV – 270 GeV >3x105 • Electron flux up to 400 GeV 6x106 • Proton flux up to 700 GeV 3x108 • Electron/positron flux up to 2 TeV (from calorimeter) • Light nuclei (up to Z=6) up to 200 GeV/n He/Be/C: 4 107/4/5 • Antinuclei search Sensitivity of 3x10-8 in He-bar/He • Unprecedented statistics and new energy rangefor cosmicray physics • e.g. contemporary antiproton & positron energy, Emax 40 GeV • Simultaneous measurements of many species – constrains secondary production models 1 HEAT-PBAR flight ~ 22.4 days PAMELA data 1 CAPRICE98 flight ~ 3.9 days PAMELA data

7. PAMELA milestones • Launch from Baikonur: June 15th 2006, 0800 UTC. • ‘First light’: June 21st 2006, 0300 UTC. • Detectors operated as expected after launch • Different trigger and hardware configurations evaluated • PAMELA in continuous data-taking mode since commissioning phase ended on July 11th 2006 • As of ~now: • > 300 days of data taking (70% live-time) • ~5.5 TByte of raw data downlinked • ~610 million triggers recorded and under analysis

8. e+ p (He...) e- - p - + Trigger, ToF, dE/dx Anticoincidence system reduces background. Sign of charge, rigidity, dE/dx Electron energy, dE/dx, lepton-hadron separation NB: e+/p: 103 (1 GeV) → 5.103 (10 GeV) p’/e-: 5.103 (1 GeV) → <102 (10 GeV)

9. Signal (SUSY)… … background

10. CAPRICE balloon experiment, 1998 Antiprotons AMS-01: space shuttle, 1998 PAMELA Secondary production ‘C94 model’ + primarycc distortion Secondary production (upper and lower limits) Simon et al. ApJ 499 (1998) 250. Primary production from cc annhilation (m(c) = 964 GeV) Secondary production(CAPRICE94-based) Bergström et al. ApJ 526 (1999) 215 Ullio : astro-ph/9904086

12. Z=1 Z=2 g~2.76 g~2.71 Preliminary !!! Galactic p and He spectra

14. PoGOLite - polarization of soft gamma-rays • DAQ system • Dimensioned for long duration flights • No HV supply lines • Flash ADC recording of all non-zero waveforms • Memory stick storage • Attitude control • Design adapted from HEFT. • Goal: 5% of F.O.V. = ~0.1 degrees • 2 star cameras, DGPS, 2 gyroscopes, 2 magnetometers, accelerometer. Axial and elevation flywheels. • Star cameras are primary aspect sensors. Acquires 8th mag. stars in daylight at 40 km.

15. Measuring polarisation • Incident g deposits little energy at Compton site • ‘Large’ energy deposited at photoelectric absorption site •  large energy difference • Can be distinguished by simple plastic scintillators (despite poor intrinsic energy resolution) • g from a polarised source undergo Compton scattering in a suitable detector material • Higher probability of being scattered perpendicular to the electric field vector (polarisation direction) • Observed azimuthal scattering angles are therefore modulated by polarisation Array of plastic scintillators Photoelectric absorption E g Compton scatter

16. Well-type phoswich detectorA narrow field-of-view and low background instrument Valid event • Pink: Phoswich Detector Cells (total 217units) • Orange: Side Anti-counter Shield (total 54 BGO) • Yellow: Neutron Shield (polyethylene) 140 cm Phoswich Detector Cell

17. PoGOLite polarimeter – schematic 60 cm 100 cm

18. P o G OLite g SLAC / Stanford- KIPAC KTH, Stockholm University Tokyo Institute of Technology, Hiroshima University, ISAS/JAXA, Yamagata University. [25 – 80 keV] g • Gamma- / X-rays can be characterised by their energy, direction, time of detection andpolarisation • Polarisation only measured once (OSO-8, 2.6 & 5.2 keV,1976) • Measuring the polarisation of gamma-rays provides a powerful diagnostic for source emission mechanisms • Polarisation can occur through scattering / synchrotron processes, interactions with a strong magnetic field •  sensitive to the ‘history’ of the photon e.g. G L A S T [10 keV – 300 GeV]

19. Synchrotron emission: • Rotation-powered neutron stars (eg. the Crab pulsar) • Pulsar wind nebulae(eg. the Crab nebula) • Jets in active galactic nuclei • Compton scattering: • Accreting disk around black holes (eg. Cygnus X-1) • Propagation in strong magnetic field: • Highly magnetised neutron stars • Expected polarization is a few % - ~20% • →Need a very sensitive polarimeter Polarisation in soft g-ray emission - PoGOLite 6h flight: +Crab: distinguish between emission models Polar Cap, Outer Gap Caustic Models +Cyg X-1: reflection component in hard state - Long duration flight + Her X-1: cyclotron absorption lines. PoGOLite is optimised for point-like sources covers25-80 keV rangeand detects10% pol in 200 mCrab sources ina 6 hour balloon observation

20. Engineering flight: 2009 / Science flight: 2010 Primary Northern-sky targets (6h) • Proposed location: NASA Columbia Scientific Balloon Facility, Palestine, Texas • Nominal ~6 hour long maiden flight • Total payload weight ~1000 kg • 1.11x106 m3 balloon • Target altitude ~40 km • Engineering flight from Sweden planned for 2009. Long duration Sweden to Canada also proposed. Accreting X-ray pulsar High-mass X-ray binary Pulsar / SNR

21. GLAST - Large Area Space Telescope Gamma-ray Large Area Space Telescope • France • IN2P3, CEA/Saclay • Italy • Universities and INFN of Bari, Perugia, Pisa, • Roma Tor Vergata, Trieste, ASI, INAF • Japan • Hiroshima University, ISAS, RIKEN • United States • CSU Sonoma. UC Santa Cruz, Goddard, NRL, OSU, • Stanford (SLAC and HEPL), Washington, St. Louis • Sweden • Royal Institute of Technology (KTH), Stockholm University, • Kalmar University Principal Investigator: Peter Michelson (Stanford & SLAC) ~270 Members (includes ~90 Affiliated Scientists,37 Postdocs, and 48 Graduate Students)

22. GLAST Key Features Imaging gamma-ray telescope Two GLAST instruments: LAT (Large Area Telescope): 20 MeV – >300 GeV GBM (GLAST Burst Monitor) 10 keV – 25 MeV Launch: February, 2008. 5-year mission (10-year goal) Large area Large field of view Large energy range Sub-arcmin source localization Superior deadtime Energy resolution @ 10 GeV < 6 %. Large Area Telescope (LAT) GBM

23. GLAST Sensitivity GLAST Burst Monitor (GBM): 10 keV – 25 MeV Large Area Telescope (LAT): 20 MeV – 300 GeV Launch: early 2008 • 30 times better sensitivity • (5x for GRBs) • Good localization 30’’- 5’ • (FOV 2-3 sr) • Good energy resolution ~10% • 50 – 150 bursts/year • Several spectral components? • Self-compton component? • IC ambient rad. field? • IC photospheric radiation? • Ultra relativistic hadrons induce EM • cascades through photomeson and • photo-pair production

24. EGRET all years E>100 MeV

25. GLAST 1 Year E>100 MeV

26. Anticoincidence shield Conversion foils Particle tracking detectors e+ e– Calorimeter Detection technique • Tracker: Solid state detector Si-strip pair conversion tracker for gamma-ray detection and direction measurement. • CsI calorimeter: energy measurement. • Plastic scintillator anti-coincidenceshield (ACD): background rejection charged particles. • Signature of a gamma event: No ACD signal 2 tracks (1 Vertex)*

27. Overview of Large Area Telescope Precision Si-strip Tracker 18 XY tracking planes. Single-sided silicon strip detectors (228 mm pitch) Measure the photon direction; gamma ID. EGRET: spark chamber, large dead time, Hodoscopic CsI Calorimeter Array of 1536 CsI(Tl) crystals in 8 layers. Measure the photon energy; image the shower. EGRET: monolithic calorimeter: no imaging and decreased resolution Segmented Anticoincidence Detector 89 plastic scintillator tiles. Reject background of charged cosmic rays; segmentation reduces self-veto effects at high energy. EGRET: monolithic ACD: self-veto due to backsplash  e– e+ Tracker ACD [surrounds 4x4 array of TKR towers] Calorimeter • Field of View factor 4 • Point Spread function factor > 3 • effective area ( factor > 5 • Results in factor > 30 improvement in sensitivity below < 10 GeV, and >100 at higher energies. • Much smaller dead time factor ~4,000 • No expendables

28. GLAST science menu:Universe is largely transparent at LAT energies: high-z and cosmic accelerators 0.01 GeV 0.1 GeV 1 GeV 10 GeV 100 GeV 1 TeV Active Galactic Nuclei Bazars: bulk of luminosity -  EBL: attenuation of AGN spectra -SFH Solar flares Unidentified sources Pulsars, cf. PoGO Gamma Ray Bursts Cosmic ray acceleration: Resolve SNR Quantum Gravity ? Strange Quark Matter ? Dark matter(decay exotic, annihil. LSP neutralinos): large area, low bkg, emission line

29. High optical depth: >1 Low optical depth: <1 Photospheric radius: rph = 6*1012 L52G2-3 cm

30. GRB: Broad band spectral coverage To find out more, we need a broader spectral coverage. Composite spectrum of GRB 930131; BATSE, COMPTEL, and EGRET instruments COMPTEL: 0.75 – 30 MeV EGRET: 30MeV-30GeV 20keV 200MeV Bromm & Schaefer 1999

31. Beyond the 20keV-2MeV band: GRB 941017 Light curves Gonzales et al., Nature 2003 Non-thermal Band-function BATSE-LAD Energy Spectra High energy Power-law constant? EGRET 1-10 MeV EGRET 10-200 MeV hadrons=> EM cascades (photo-meson and photo-pair prod) 200 MeV

33. Spectral components in the theoretical spectrum: Thermal, photospheric emission (black body) Thermal Photophere, T Mészáros et al. (2000) Photospheric Comptonization, PHC . 2 =L/Mc ”Common” in astro- physics Shock Synchrotron, S GLAST BATSE Shock pair-dominated Comptonization, C See also Lyutikov & Usov (2000) , Drenkhahn & Spruit (2002), Daigne & Mochkovitch (2002), Rees & Mészáros (2004), Pe’er, Mészáros, & Rees (2005)

34. Experimental Particle Physics @ KTH KTH ATLAS group: Bengt Lund-Jensen (Prof) Stefan Rydström (Electronics engineer) Karl-Johan Grahn (PhD student) Mohamed Gouighri (Guest PhD student) Per Hansson (PhD student) Space radiation: Christer Fuglesang (Aff. Prof) Oscar Larsson (Dipl. Student)

35. Barrel presampler Operational in ATLAS Analysis of cosmic muons All 64 sectors in place with electronics Cosmic muon data analysis

36. HV status of the ATLAS barrel presampler KTH shares the responsibility for the presampler. (KTH, Grenoble, Casablanca). The presampler is constructed by assembling anode and cathode electrodes to form ~2 mm wide gaps of liquid argon. Some short circuits in the gaps appeared during and after installation in ATLAS.These shorts are assumed to be due to dust between the electrodes. A short circuit results in one side of a group of anodes being inactive, giving only half the signal in 32 readout channels, i.e. increaing the noise. • Standard electromagnetism also works in particle physics experiments: • By discharging a high voltage capacitor over the short • circuit the dust can be destroyed. • In worst case thin copper lines on the anode • electrodes work as a fuses • So far we believe that we have burnt the dust rather than the copper lines.

37. Presently there are 3 short circuits (out of 79616 cells), all reappering some time after the burning campaign made in October 2006..

38. Optical cables for the Liquid Argon calorimeters • Delivered, spliced and tested Electronics room. Back end read- out electronics Stefan Rydstrom slicing the optical cables. The whole LiAr calorimeter has been read out

39. HV supplies: (KTH participates) problems with week components solved by modifications. All modules retrofitted. Working as expected. Remaining modules of new type will be delivered by end of September All optical cables connected to the back-end electronics.

40. Goal: Improving calorimeter resolution and linearity for hadronically showering particles by applying relevant weightings and corrections. Activities Comparison of beam test data (pion data) with Geant4 Monte Carlo. Dependence on hadronic physics lists. Improvements in liquid argon calorimeter simulation, e.g. saturation effect for heavily ionizing particles. Investigation of weighting schemes exploiting layer correlations. Based on principal component analysis of energy deposited in the different calorimeter samplings, which capture properties of shower development. Dead material corrections. Correct for e.g. energy loss in cryostat between liquid argon and tile calorimeters. Hadronic calibration

41. Hadronic Calibration in the ATLAS Barrel Combined Beam Test • Allows us to validate calibration procedures on real data in a controlled environment. • Data taken fall 2004, analysis still ongoing. • All the sub detectors of the ATLAS barrel region • inner tracker • liquid argon electromagnetic calorimeter • tile hadronic calorimeter • muon tracker together on at the H8 SPS beam line at CERN. • Electrons/positrons, pions, protons, energies 1–320 GeV

42. Dead material corrections applied to Monte Carlo and test beam data

43. SUSY at LHC • Mass and branching fractions of the various SUSY particlea are model dependent, (e.g. ways to break SUSY (GMSB,mSugra,etc,..)) • Gluino and squark production dominates at LHC • R-parity conserved: complex cascade decay chains end with lightest SUSY particle (usually neutralino) • Focus on final state -> distinct signature is missing transverse energy (MET)

44. Desire (Dose Estimation by Simulation of the ISS Radiation Environment) Work by Tore Ersmark (left after PhD for a private company) Idea: Use Geant4 for particle transport through the space station and especially the Columbus module in order to estimate the radiation dose for astronauts

45. Dose rate dependenceon geometry • Simulation results are dependent on level of detail of Geant4 geometry models • Studied using three versions of Columbus geometry models with different level of detail • C1 – Very simple, mass of 4400 kg, 10 volumes • C3 – The most detailed model, correct total mass of 16750 kg,750 volumes • C2 – Simplified version of C3,23 volumes

46. Dose rate dependence on geometry • Increasing shielding thickness  • Decreasing trapped proton dose rate • Increasing or constant GalacticCR proton dose rate • Increased amount of shielding may be harmful in some cases! • Similar results for C2 and C3  • C3 detail unnecessary in this case • C3I1 model used in studies

47. Continuation beyond Desire Geant4 not perfect: Heavy ion models are only valid up to C. Ion-nuclei interaction models only valid for < 10GeV/N. Need to compare simulations and data. Data available from the Sileye3/Alteino detector on board ISS. • 8 silicon detector planes 8x8 cm2 (380 μm thick) • each plane is divided in 32 strips with 2.5mm pitch • trigger is provided by two scintillators Now: diploma work to analyze data and compare with simple Geant4 model

48. FIN

49. SUSY at LHC • Many (more or less conventional) ways to break SUSY (GMSB,mSugra,etc,..) • mSugra – hidden sector at GUT scale explicitly breaks susy -> 5 parameters (m0,m1/2,A0,mu,tanBeta) • Gluino and squark production dominates at LHC • Mass and branching fractions model dependent • Cross-sections model independent • gluinos/squarks cascade in complex decay chains • R-parity conserved: decay chain ends with lightest SUSY particle (usually neutralino ) Cross section (pb) • Focus on final state -> distinct signature is missing transverse energy (MET) Average particle mass (GeV)

50. SUSY predicting backgrounds (In collaboration with Stockholm University) • Studying signature with two leptons+jets+missing momentum • ~95% of the background is top quark pair production Smoking gun of SUSY events with large missing transverse momentum • Early measurements need background estimates from data • Our earlier experiences from top quark analyzes at the Tevatron is valuable