Status: Low-Z LPM Structured target resonance Plans (for 2015): Heavy ion bremsstrahlung
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Transcript of Status: Low-Z LPM Structured target resonance Plans (for 2015): Heavy ion bremsstrahlung
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Status:1. Low-Z LPM2. Structured target resonancePlans (for 2015):3. Heavy ion bremsstrahlung4. Positron production (8 MIMOSAs)
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STATUSLow-Z LPM
Phys. Rev. D 87, 072007 (2013)
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Preliminary
Low-Z LPM Test LPM (Migdal) theory in low-Z targetsNo indications of insufficiency at level of stat. accuracy
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Preliminary
20 GeV electrons in Copper:No signs of kink-like structure
Pile-up and background dilute the (possible) effect.
Low-Z LPM
Phys. Rev. D 87, 072007 (2013)
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STATUSStructured targets
Phys. Lett. B 732, 309 (2014)
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Structured targets – systematic investigation, Phys. Lett. B 732, 309 (2014)
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Structured targets
Measuring the formation length with a micrometer screw....
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STATUSPositron production2012 measurement
+DESY test
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Angular scans• Radiation enhancement
observed w/ 180 GeV electrons (signal = radiation above 50 GeV, ‘strong field radiation’)September 2012, CERN with 1.5 mm diamond:
-8500 -8000 -7500 -7000600
800
1000
1200
1400
1600
1800
2000
2200
Rad
iatio
n si
gnal
Goniometer step (1.7 rad)
(110) plane
1.5 mm diamond, 180 GeV e-
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MIMOSA read-out
ASTRID and DESY test
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PLANS FOR 2015
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(MAMI)
Also a testing ground for our simulation code for radiation and pair creation in crystals…
Phys. Rev. Lett., accepted
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Positron production
Factor 15 enhancement at low energies
Reduced for thicker targets
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Heavy ion bremsstrahlung
Peak structure due to finite nuclear size
(deBroglie wavelength of virtual photon of order R)
Radiation emission
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Heavy ion bremsstrahlung
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Argon 18+ bremsstrahlung20 A GeV
0 1 2 3 4 5 6 7
Photon energy
Cros
s sec
tion
[mba
rn]
0
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6
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Argon 18+ delta-
electrons
Homogeneously charged sphere
Pointlike nucleus
Approx. 1 day of (parasitic) beam in H4
Quantitative statistical analysis of sensitivity underway
Size of MIMOSA
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Delta-electrons – charge density of the nucleus
150 A GeV Ar18+, 1 day
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Publications, NA63• Since previous SPSC presentation:1. K.K. Andersen, S.L. Andersen, J. Esberg, H. Knudsen, R.
Mikkelsen, U.I. Uggerhøj, T.N. Wistisen, A. Mangiarotti, P. Sona and T.J. Ketel (CERN NA63): Experimental investigation of the Landau-Pomeranchuk-Migdal effect in low-Z targets, Phys. Rev. D 88, 072007 (2013)
2. K.K. Andersen, S.L. Andersen, J. Esberg, H. Knudsen, R. Mikkelsen, U.I. Uggerhøj, T.N. Wistisen, A. Mangiarotti, P. Sona and T.J. Ketel (CERN NA63): Measurements of the spectral location of the structured target resonance for ultrarelativistic electrons, Phys. Lett. B 732, 309-314 (2014)