MA
Sponsored Links
This presentation is the property of its rightful owner.
1 / 42

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


  • 83 Views
  • Uploaded on
  • Presentation posted in: General

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 :.

Download Presentation

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

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


MAinzer MIkrotron 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:

visible light : l=400 – 700nm

For particle-waves l=h/p :

E~100keV: electron microscope

E~1000MeV: ‚nucleon‘ structure ‚microscope‘


nucleus: a few 10-15 m

(0,0001 × Diameter of Atom)

Atom

Kern


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-)


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 )


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!


surf


surf


surf


surfin’ on

the wave


Linac Section

2 Meter, 25.000W cw Hf, 1.800.000eV


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


2 Dipole Magnets + n LINAC Passages

Much more efficient:

The RaceTrack Mikrotron (RTM)

z.B.: LINAC: 7,5MeV, 90Turns

675MeV total ( 125kW Hf-Power)


Three stage acceleration


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


1990-2006:MAMI-B

450 Tonnen, 1.28T

still not enough: 1500 MeV desired!MAMI-C


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


855MeV 1500MeV

Harmonic Double Sided Microtron Mikrotron (HDSM)


The HDSM, a world wide unique microtron variant

Successful start up: 19. Dezember 2006


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

?


Das KAOS Spektrometer = Nachweis von Kaonen


Grundriss von

MAMI C

(ca. 6500 Stunden Betrieb pro Jahr)

Diplomanden und Doktoranden

in experimenteller und theoretischer

Kern- und Teilchenphysik, Beschleunigerphysik


MAinzer MIkrotron MAMI:

Practical Training: Irradiation and

induced radioactivy

Kurt Aulenbacher

Reactor Training Course

U-South Carolina

May, 28, 2008


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


Hier sind wir !

Aerial view:

RTM 1 + 2

RTM 3

Accelerator and experiments are completely underground

typically 10-15 meters deep below ground level!


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


Example:Operation modus

I. MAMI-B

(Halle A + B + C)

Sperrbereich (’cut off’ area )

permanent cut off

due to induced radioactivity


Op-modus

II. Exp op.:

(Spektrometerhalle)

100mA bei 1.500.000.000eV

= 150kW Leistung


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),


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


Charged particles are easy to shield !

…but electrons create (neutral) gamma radiation


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


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


Pb d = 1,27 cm


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


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!


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.


X1 area in forward direction of

(low power) beam dump


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)


  • Login