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Detectors of charged particles and ions

Detectors of charged particles and ions. Mostly high efficiency (ionization will start immediately), big enough detector – absorption of whole energy. 1) Gas filled detectors a) Ionization chambers b) Proportional counters c) Multiwire chambers

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Detectors of charged particles and ions

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  1. Detectors of charged particles and ions Mostly high efficiency (ionization will start immediately), big enough detector – absorption of whole energy 1) Gas filled detectors a) Ionization chambers b) Proportional counters c) Multiwire chambers d) Time projection chambers 2) Scintillation detectors 3) Semiconductor detectors Silicon detectors of alpha particles produced by CAMBERA company Hadron calorimeter of NA49 experiment Calorimeter of ATLAS experiment

  2. Scintillation detectors Response on heavy charged particles: Non-linearity for L = f(E) starts to manifest Limited number of scintillation centers → saturation – part of energy is not converted Semiempirical Birks equation: (mainly for organic scintillator) Response of fast plastic scintillator on heavy ions Total light output L: A – absolute scintillation efficiency, kB – parameter which joins density of ionization centers with ionization saturation: Many other variants of semiempirical equations Dependency of light output on ionization losses Dependency of light output on kB

  3. L(long) L(short) Differentiation by means of comparison of light outputs with different time window: BaF2 spectrometer TAPS (right) and CsI(Tl) (left) Dependency of response on energy for plastic scintillator NE102A Differentiation of different ions by means of analysis of puls shape: Short and long components of de-excitation – de-excitation of different excited states (ratio of their excitation probability depends on ionization losses) Possibility to use two types of scintillator with different de-excitation time ΔE-E telescopes 2 mm plastic and CsI scintillator

  4. Hadron calorimeters End of hadron shower E ~ ETHR(π) ~ 100 MeV – threshold of πmesons production Transversal energyflow and longitudinal energyflow – escape from detector Uncertainty consists of three components: 1) statistical fluctuations: 2) detector – noise, pedestals: 3) calibration – photomultiplier nonlinearity, in homogeneities: Detection of large amount of created neutrons (5 neutrons/GeV), their energies ~ 8 MeV Compensation calorimeter: Bigger response to particles of elmg component Le/Lh = 1,1 – 1.35 Suitable active and passive calorimeter parts: Le/Lh≈ 1 238U – absorption of slow neutrons, shielding from soft photons by layers of materials with small Z Forward calorimeter of ALICE experiment Absorption of photons from neutron captures by means of atoms with large Z Possibility of correction during later analysis – usage of information about course of shower

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