Status:1. Structured target resonance2. Magnetic suppression3. Low-Z LPM, Undulator-rad., Quantum

suppression

Plans:4. Heavy ion bremsstrahlung5. Positron production

STATUS

• 2x20 micron Au/Ta foils separated by 0 – 5000 microns (tolerance about 2 microns)

Signal ‘on top of’ about 2.0 (in these units) for separations in microns

2040120100

Structured target resonance

Measuring the formation length with a micrometer screw....

PreliminarySPS H4 exp., Sept. 2011

Structured target resonance

If the deflection angle over half a formation length

exceeds the ‘emission angle’

which happens for photons:

Suppression (crude model):

More elaborate theory needed...

Magnetic suppression

Magnetic suppression

•Material immaterial.•Higher fields move effect to higher photon energies.• Magnitude insensitive

•BUT: The effect will not be visible due to LPM suppression!

10% effect...

Magnetic suppression

•Material immaterial.•Higher fields move effect to higher photon energies.• Magnitude insensitive

NB!

300% effect!

Magnetic suppression

MCS

Field

The effect will not be visible due to LPM suppression!

Low-Z LPM• SLAC (1995) and CERN

(2001) indicate problems with low-Z targets.

• Test LPM theory in low-Z targets

• Analysis in progress (deconvolution of synchr. rad. poses problems)

from Electron/Positron Channeling in a Single CrystalA. Solov’yov, A. Korol, W. Greiner et al.

Initially tested (unsuccesfully) by NA63

Undulator radiation

Undulator radiationH. Backe, W. Lauth, A. Solov’yov, W. Greiner, U. Uggerhøj, J. Esberg, J.L. Hansen

Il Nuovo Cimento C, 34, 157-165, 2011Il Nuovo Cimento C, 34, 175-180, 2011

MAinz MIcrotron (MAMI)

0.01 0.1 1 10 1001E-3

0.01

0.1

10.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.0

0.2

0.4

0.6

0.8

1.0

I/Icl

0.001 0.01 0.1 1 10 100 1000 10000 1000000.001

0.01

0.1

1

10

Critical energy

Classical synchrotron radiation

Incident energy,Ee=10 GeV

Standard magnet, B = 1 T, 1m Si <110>max, Bequiv = 25.000 T, 0.1 mm

dN

/d

Photon energy [MeV]

Quantum Suppression

-4 -2 0 2 40.0

0.2

0.4

0.6

0.8

1.0

Qua

ntum

sup

pres

sion

of i

nten

sity

log10

(1/), log10

(C)

Synchrotron radiation Blankenbecler & Drell, eq. (7.5)

Classical: -> 0 => Cb -> infty

Quantum Suppression

Quantum Suppression

Analysis in progress• Factor 2 problem with normalization…

MonteCarlo

‘Fudge-factor’normalization

PLANS

Heavy ion bremsstrahlung33 TeV Pb82+ → Pb82+

γ = 170

Intact projectile

Scattering on a single rigid objectof charge Ze and mass M

Coherent scattering on Z quasi-free protons each of mass Mp

Incoherent scattering on individual quasi-free protons

Approx. binding energy per nucleon

Wavelength corresp. to nuclear size

Weizsäcker-Williams type calculation

BS never becomes the dominating mechanism in energy loss

Previous theories Now

Heavy ion bremsstrahlung

Heavy ion bremsstrahlung

Delta-electronsFinite nuclear size

…studies with aligned crystals – to be used for e.g. CLIC, LHeC previous studies with tungsten

High multiplicity and ’low’ energies (10 MeV e+)

Positron production

Positron productionMIMOSA detectors (M. Winter, Strasbourg)

• Vertex detectors for CLIC (?)

Positron production

Applications for funding – 100 kCHF – submitted

Funding expected by December 2011

11 MIMOSAs + DAQ delivered February 2012

Status:1. Structured target resonance2. Magnetic suppression3. Low-Z LPM, Undulator-rad., Quantum

suppression

Plans:4. Heavy ion bremsstrahlung5. Positron production