Denis Anielski Detector systems to find HFS of 209 Bi ESR Emission characteristics Counting rates at existing mirror section Straight on detector option Parabolic mirror system Outlook Denis Anielski, Volker Hannen, Raphael Jöhren, Christian Weinheimer Westfälische Wilhelms-Universität Münster

Denis Anielski Relativistic Doppler Effect λ = λ´γ(1- βcos(θ))θ= 0° → 640nm λ´ = 1555nm θ= 40° → 1000nm Observed angle Boost Relativistic Doppler Effect and Boost (β = 0.71)

Denis Anielski Simulation of Boost Polar angles in the comoving system Polar angles in the lab system (Isotropic light source) A(0°,10°) = 4% A(10°;30°) = 25% A(10°;50°) = 52% →Most photons not in straight forward direction, because of sin(θ) in solid angle!

Denis Anielski Ideas For Detector Systems

Denis Anielski General Assumptions Number of excited ions: 2 e5 Lifetime in lab system: 82 ms [1] Lifetime in comoving system: 116 ms QE = 10% Circumference of ESR: 108 m β = 0.71 [1] V. M. Shabaev, PHYSICAL REVIEW A, JAN 1998

Denis Anielski Mirror System 10 elliptical mirrors on a 65cm section Original simulation software not available First order estimate: geometric count rate estimate Realistic simulations using GEANT4 under progress

Denis Anielski Estimated counting rate Counting rate is proportional to  Emitted photons per second N Ph = N/tau = 1,72 e6  Ratio of totally emitted photonsA = 0.38 (646 nm – 950 nm; 5°-37° )  Loss by reflexion and transmission R*T = 1/3 (R=0.35!!!)  Quantum efficencyQE = 0,1  Relevant beam sectionb = 0.065m/ 108m  Geometry of mirror systemg = 2/3  Number of windows(dia: 7cm)# = 3 →f = N Ph · A · g · RT · QE · b · # = 26 Hz

Denis Anielski Straight on option Diameter of window: 60mm Straight beam section: 17 m Distance – beam – detector: 3,5 m All Photons are focused on detector by a lense Transmission of lense: 0.9 →0,36 Hz(simulation c++)

Denis Anielski Parabolic mirror Detects forward emission → short wavelengths

Denis Anielski Parabolic mirror Assumptions Reflectivity coefficient: 0.8 Hole in mirror with diameter of 2cm for the beam GEANT4 model

Denis Anielski flange option Diameter of flange for mirror: 10 cm Diameter of flange for detector: 3.8 cm Distance: Beam - Detektor: 30 cm Straight section before mirror: 5 m Radius of mirror: 5 cm Lightguide as interface from window to detector GEANT4 simulation (Volker Hannen) →15 Hz

Denis Anielski flange option

Denis Anielski flange option – C++ Simulation Diameter of flange: 20 cm Distance: Beam - Detektor: 25 cm Straight section before mirror: 5 m / 10 m Radius of mirror: 7.5 cm Radius of detector/ focussing system: 3 cm Counting rate is multiplied by 0.9 because of slit →45 Hz / 60 Hz (Flange is just in front of mirror system!) Possible improvement with recessed exit window (distance beam – exit window = 15cm):154 Hz

Denis Anielski CPM beam tests Two setups have been installed at ESR yesterday Investigations of background photons and behaviour of CPM next to dipole magnet Positions: – 2-flange option – Straight on option Detectors: Channel-Photomultiplier – Easy to handle – Low dark count rate – Only 2% QE around 650nm – Suitable for 244nm transition at SPECTRAP (QE= 18%)

Denis Anielski Conclusions Mirror system:  26 Hz, but dark counts of three detectors, broad wavelength range  Reflexion of mirror?  Not all three windows present  ??? Straight on  very low rate ( < 1Hz)  ??? Parabolic mirror  System with highest counting rate on a SINGLE detector  Small wavelengths (640 – 680nm)  !!!

Denis Anielski Outlook Test of Hamamatsu R PMT (suitable detector for parabolic mirror system) Detailed GEANT4 simulation of existing mirror system and search for best parameters of parabolic mirror system