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MA inzer MI krotron MAMI : A precision accelerator for nucleon structure investigations

MA inzer MI krotron MAMI : A precision accelerator for nucleon structure investigations. Kurt Aulenbacher Reactor Training Course U-South Carolina May, 28, 2008. l : Wavelength. d: object size. d:. required resolution. l < d. l :. Lightwaves and particle waves. l :.

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MA inzer MI krotron MAMI : A precision accelerator for nucleon structure investigations

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  1. MAinzer MIkrotron MAMI: A precision accelerator for nucleon structure investigations Kurt Aulenbacher Reactor Training Course U-South Carolina May, 28, 2008

  2. l: Wavelength d: object size d: required resolution l < d

  3. l: Lightwaves and particle waves l: visible light : l=400 – 700nm For particle-waves l=h/p : E~100keV: electron microscope E~1000MeV: ‚nucleon‘ structure ‚microscope‘

  4. nucleus: a few 10-15 m (0,0001 × Diameter of Atom) Atom Kern

  5. e Nucleus, z.B. Helium: Proton(1919) and Neutron(1931) (Nucleons) very complicated ‚many body‘ system n p p n Electron(1898) Proton: 10-15m, charge e+ Neutron: 10-15m, „neutral“ (pointlike , charge e-)

  6. UHV ~ -100.000V ElektrostaticAcceleration, Vacuum kinetic Energy of Electrons: E = 100.000eV ( d.h. v= 54,8% •c = 164.350km/s l = 4 • 10-12m )

  7. 25.000 W Power Microwave Resonating Structure with longitudinal field components and appr. phase shifts …allows for nearly continous energy transfer from field to particle!

  8. surf

  9. surf

  10. surf

  11. surfin’ on the wave

  12. Linac Section 2 Meter, 25.000W cw Hf, 1.800.000eV

  13. Achieving several hundred MeV by brute force: LINAC For c.w. 800MeV required: (LINAC): - ca. 400 Sections - ca. 1km length - 15MWc.w. high frequency power

  14. 2 Dipole Magnets + n LINAC Passages Much more efficient: The RaceTrack Mikrotron (RTM) z.B.: LINAC: 7,5MeV, 90Turns 675MeV total ( 125kW Hf-Power)

  15. Three stage acceleration

  16. Operating since 1990 for more than 100000 hours RTM 2 51 Rezirkulationen 180MeV RTM 1 18 Rezirkulationen 15MeV RTM 3 90 Rezirkulationen 850MeV LINAC 3.5MeV Elektronenquelle 100keV

  17. 1990-2006:MAMI-B 450 Tonnen, 1.28T still not enough: 1500 MeV desired!MAMI-C

  18. 250 to 250 to 2000 to 2000 to 450 to 450 to 250 to 250 to The double sided microtron (K.H. Kaiser et al.) 43 Turns, 855MeV 1,5GeV

  19. 855MeV 1500MeV Harmonic Double Sided Microtron Mikrotron (HDSM)

  20. The HDSM, a world wide unique microtron variant Successful start up: 19. Dezember 2006

  21. 2 1 Ein, pin, Sin 3 Beispiel: E=1508MeV ± 0.030MeV (0.002%) I= ~ pA – 100mA Strahlposition konstant auf ~ 10mm Ei, pi, Si Eout, pout, Sout ? knowing 1 + 2 + 3:-get to know Koinzidenz-Experiments need cw-beams ! The Goal: Understanding the ‚Nucleon‘ “Vielkörperstruktur stark wechselwirkender Systeme” Nukleon (Proton, Neutron) ~ 10-15m ?

  22. Das KAOS Spektrometer = Nachweis von Kaonen

  23. Grundriss von MAMI C (ca. 6500 Stunden Betrieb pro Jahr) Diplomanden und Doktoranden in experimenteller und theoretischer Kern- und Teilchenphysik, Beschleunigerphysik

  24. MAinzer MIkrotron MAMI: Practical Training: Irradiation and induced radioactivy Kurt Aulenbacher Reactor Training Course U-South Carolina May, 28, 2008

  25. Irradiation of samples with MAMI at 855MeV and simultaneous measurement of neutron radiation field in accesible area., Hall clearance and installation of ‚cut off‘ area Investigation/identifaction of induced radioactivity: by gamma spectroscopy Our program this afternoonTwo groups, exchanging after about 1 hour

  26. Hier sind wir ! Aerial view: RTM 1 + 2 RTM 3 Accelerator and experiments are completely underground typically 10-15 meters deep below ground level!

  27. high power (150kW), high energy particle sourceno persons allowed in areas where accelerator operates secondary radiation : gamma rays (Bremsstrahlung up to 1500MeV) tertiary radiation: Photoneutrons (up to 1000MeV) neutral particles are more difficult to shield due to missing continous ionisation! Primary radiation disappears after shutdown, induced radioistopes may persist! Radiation and Radioisotopes at MAMI

  28. Example:Operation modus I. MAMI-B (Halle A + B + C) Sperrbereich (’cut off’ area ) permanent cut off due to induced radioactivity

  29. Op-modus II. Exp op.: (Spektrometerhalle) 100mA bei 1.500.000.000eV = 150kW Leistung

  30. Rückl. Vorl 300kW High power beam dump () Al-beads/Water (Vol60/40Strahlungslänge 14cm) Transferefficiency Beam-powerwater >95% Shielding 1.5 Meter heavy concrete + 6meter soil. (upwards),

  31. p High energy accelerators E>100MeV have very complicated radiation field. Proton worse than than electron. Electrons (primary) Bremsstrahlung (secondary) Photohadrons (tertiary) Neutral components are difficult to shield against: Photons and Neutrons e

  32. Charged particles are easy to shield ! …but electrons create (neutral) gamma radiation

  33. Interaction Gamma-radiation • Photoeffect: s~E-7/2, ~Z4 • dominant for E < 100 keV • efficient with high nuclear charge Z • Elektronen der K-Schale • Comptonscattering: s~E-1, ~ Z/A • dominant 100 keV < E < 10 MeV • Paircreation: s~ln(E) (0<1MeV) ~Z2 • dominant ~ 10 MeV < E • Absorbermaterial mit hoher Ordnungszahl

  34. Sum of cross sections and cascade High energies: Pair creation dominant: ge++e-2g2e++2e-4g4e++4e- typical length scale: ‚radiation length‘ Pb: 0.56cm/Fe:1.76cm/ heavy concrete: 5cm /Water 36cm

  35. Pb d = 1,27 cm

  36. Pair creation leads to a large number of ionizing particles dose increases (at first) with shielding thickness. In deeper layers main energy dissipation by compton scattering exponetial damping of energy flux and associated dose. Typical attenuation constant: l=1/(50cm2*g-1) 6 GeV Elektronen Due to relativsitic effect energy transport remains concentrated in narrow forward cone Shielding thickness at MAMI in forward direction at least 5 Meter heavy concrete (or äquivalent) lateral: 2 Meter

  37. Photo-Neutrons Photo-Neutrons for Eg< 100 MeV by Giant resonance neutrons! for >170MeV:HE-neutrons by Pion production p+gp++n These are much more difficult to shield!

  38. Dose rate behind thick shielding mFL … Massenbelegung λ(Q;E)Abschwächungskonstante d … Abstand zum Strahlungsort we are here… Liefert a.a.O. 54mSv/h bei 150 Watt.

  39. X1 area in forward direction of (low power) beam dump

  40. X1 area is accessible ‚controlled area during beam dump operation. (1meter iron+ 2 Meters heavy concrete shielding) Todays exercise: I) comparison of standard neutron monitor with ‚wide range‘ detector II) investigation of irradiated samples by g-spectroscopy Low power beam-set-up beam dump: irradiation of test samples (Cu,Fe,Al)

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