H, He, Li and Be Isotopes in the PAMELA-Experiment Wolfgang Menn University of Siegen On behalf of the PAMELA collaboration International Conference on Particle Physics and Astrophysics Moscow 09-Oct-2015

PAMELA Payload for Antimatter Matter Exploration and Light Nuclei Astrophysics A wide Range of Measurements: Search for Antimatter ( p, He, e + ) and Dark Matter Study of Cosmic Ray Propagation: p, He, e -, B, C Solar Particles Solar Modulation Interactions between energetic Particles and the Earth Magnetic Field We published results in all these fields

Antiparticles (antiprotons, positrons), secondaries from homogeneously distributed interstellar matter (light nuclei) PAMELA Secondary Cosmic Rays

Tuning of cosmic-ray propagation models with measurements of secondary/primary flux ratio 2 H/ 1 H and 3 He/ 4 He are complimentary to B/C measurements in constraining propagation models (Coste et al., A&A 539 (2012) A88) Light Nuclei and Isotopes

Adriani et al., ApJ 791 (2014), 93 Tracking performance: σ x = 14 μm, σ y = 19 μm MDR = 250 GV Modelization of cosmic-ray propagation in the Galaxy Boron and Carbon Fluxes and B/C Ratio

Adriani et al., ApJ 791 (2014), 93 Tracking performance: σ x = 14 μm, σ y = 19 μm MDR = 250 GV Modelization of cosmic-ray propagation in the Galaxy Boron and Carbon Fluxes and B/C Ratio

H, He, Li and Be Isotopes

GF: 21.5 cm 2 sr Mass: 470 kg Size: 130x70x70 cm 3 Power Budget: 360W PAMELA and its Measured Quantities Velocity (β) (Multiple dEdx)

Isotope Measurements with the Velocity versus Rigidity Technique Velocity versus Rigidity Technique Velocity versus Rigidity Technique: Rigidity from spectrometer Beta from ToF, dEdx, … Mass Resolution: β-Measurement Spectrometer

Spectrometer: microstrip Si tracking system + permanent magnet Measures Rigidity R: R=p / Z∙e -6 layers of silicon microstrip detectors - 3 µm resolution in bending view - magnetic field ~ 0.45 T - → MDR ~ 1 TV PAMELA Instrument: Spectrometer

PAMELA Spectrometer 6 3 µm, 0.45 T → MDR ~1000 GV (dR/R) mult ~ (x/X 0 )/(beta · B·dL) Silicon Tracker doesn`t need support structure → minimal multiple scattering ~3.5 %

Time-Of-Flight (TOF): plastic scintillators + PMT -time resolution: ~ 300 ps for Z = 1 ~ 100 ps for Z = 2 ~ 85 ps for Z = 3 ~ 80 ps for Z = 4 PAMELA Instrument: Time-of-Flight

ToF: Charge (after conversion from dEdx) vs. beta Charge Selection Trk: dEdx vs. Rigidity Be Li

Velocity (ToF) versus Rigidity Technique Velocity (ToF) versus Rigidity Technique

Mass Resolution for Flight Data Helium

Velocity versus Rigidity Technique Velocity versus Rigidity Technique PAMELA Tof + Spectrometer Expected Mass Resolution for 4 He 4 He

Isotope Measurements with the Velocity versus Rigidity Technique Velocity versus Rigidity Technique Velocity versus Rigidity Technique: Rigidity from spectrometer Beta from ToF, Cherenkov, dEdx… Mass Resolution: β-Measurement Spectrometer Multiple dE/dX measurement

Electromagnetic W/Si calorimeter 44 Si layers (X/Y) +22 W planes 380 µm silicon strips, 4224 channels 16.3 X 0, 0.6 λ I Dynamic range ~1100 mip PAMELA Instrument: Calorimeter

Calorimeter: Truncated Mean Method Only usuable for non-interacting events Energy loss in each silicon layer of the calorimeter: Cut away highest 50% Use the lower 50% (black points) to calculate a mean dEdx

Refined Selection Method Strict Selection: All events with interactions are discarded Refined selection: Use information of the „clean“ part in the calorimeter, neglect the lower part Discarded !

Multiple dE/dx versus Rigidity Technique Multiple dE/dx versus Rigidity Technique

Mass Resolution with Calorimeter “Truncated Mean” 4 He

Mass Resolution For Lithium

Mass Resolution For Beryllium

Getting Isotope Counts (ToF) Compare flight data distributions with „model“ distributions ToF H & He: 1/β distributions are gaussian => do a gaussian fit

Getting Isotope Counts (ToF) ToF Li & Be: Work in progress… Create simulated 1/β distributions Compare flight data distributions with „model“ using Likelihood- Software like TFractionFitter, RooFit… TFractionFitter: Black Points: Data Red / Blue / Green: Isotopes Grey: Sum

Getting Isotope Counts (Calorimeter) Truncated mean dEdx distributions are not gaussian Model: Use GEANT4- Simulation of the PAMELA-Experiment Create simulated distributions of truncated mean dEdx TFractionFitter: Black Points: Data Red / Blue / Green: Isotopes Grey: Sum

Getting the Efficiency in the Calorimeter GEANT4- Simulation of the PAMELA-Experiment (Example: 3 He and 4 He) Derive Efficiency for specific set of selection cuts Flight Data Tracker dEdx 4 He 3 He Flight Data 1/β 4 He 3 He Flight Data ToF dEdx 4 He 3 He 3 He 4 He

Deriving Isotopic Fluxes and Ratios for H and He Efficiencies Livetime Interaction losses Geometry Factor Unfolding Make Use of ToF Analysis published „Measurement of the Isotopic Composition of Hydrogen and Helium Nuclei in Cosmic Rays with the PAMELA Experiment“ O. Adriani et al., ApJ, 770, 2, (2013) Measurement of hydrogen and helium isotopes flux in galactic cosmic rays with the PAMELA experiment V. Formato et al. NIM A, 742, p. 273–275 (2014)

Hydrogen Isotope Fluxes and Ratio using ToF & Calorimeter (2006 & 2007 Data) Preliminary

Helium Isotope Fluxes and Ratio using ToF & Calorimeter (2006 & 2007 Data) Preliminary

Lithium & Beryllium Flight Data 2006 – 2014

Lithium: ToF Lithium: ToF 2006 – 2014 Data GEANT4 simulation TFractionFitter

Lithium: Calorimeter “Truncated Mean” Method 2006 – 2014 Data GEANT4 simulation TFractionFitter 6 Li 7 Li

Beryllium: ToF Beryllium: ToF 2006 – 2014 Data GEANT4 simulation TFractionFitter

Beryllium: Calorimeter “Truncated Mean” Method 2006 – 2014 Data GEANT4 simulation TFractionFitter

So far no isotopic fluxes, only ratios Work in Progress! Li and Be spectra: Measurement of Lithium and Beryllium cosmic- ray abundances by the PAMELA experiment (ICRC 2015) Efficiencies Livetime Interaction losses Geometry Factor … Deriving Isotopic Fluxes and Ratios for Li and Be

Getting the Efficiency in the Calorimeter GEANT4- Simulation of the PAMELA-Experiment Derive Efficiency for specific set of selection cuts Check with flight data: Use redundant detectors to select flight data 6 Li and 7 Li Derive Efficiency in the same way as for simulated data ToF–β vs. R ToF-dEdx vs. R Trk-dEdx vs. R

Measurements of Lithium Isotopes

Measurements of Beryllium Isotopes 7 Be / ( 9 Be + 10 Be)

Measurements of Beryllium Isotopes (2) Difficult: Separate 9 Be and 10 Be… Large systematic error… Probably we need to use „Chi²-Method“ (or TMVA etc.) to get a better mass resolution…

Alternative Analysis: Make Use of Particle’s Slowdown Move the calculated Bethe-Bloch-Curve for a given Mass through the measured Data and calculate a Chi² value The best Chi² wins!

Mass resolution with “Bethe-Bloch-Chi²” Method 4 He Different methods still under test, work in progress…

Summary Momentum resolution of PAMELA spectrometer ca. 3.5 % H and He with Tof & Calorimeter: Analysis ( 0.1 GeV/n – 1.3 GeV/n) ready to publish Li and Be with ToF & Calorimeter: Results show that PAMELA will be able to provide new data for Lithium and Beryllium isotopes up to ~ 1.2 GeV/n Thank You !

Backup Slides

BESS MDR = 200 GV B = 0.5 T L = 1 m

ISOMAX Mass Resolution For Beryllium

Comparison ToF & Calorimeter 2.5 – 2.7 GV ToF Calorimeter: Truncated mean Chi² B.-B.

ISOMAX Mass Resolution

AMS-01 R=5.56 GV MDReff=32 GV each track layer = 0.65 % X0 (PAMELA 0.32 %) Expected He4 mass resolution: 0.4 2GV Data looks worse!

Definition of “non interacting” q tot = Total energy loss in each layer q track : Energy loss in the three strips closest to the track Perfect event: q track / q tot = 1 Old selection (until ICRC 2013): Integral q track /q tot > 0.9

PAMELA Spectrometer 6 3 µm, 0.45 T → MDR ~1000 GV CERN Beam Test Proton Data (dR/R) mult ~ (x/X 0 )/(beta · B·dL) Silicon Tracker doesn`t need support structure → minimal multiple scattering ~3.5 %