nta-hccc stato aggiornato della sperimentazione vincenzo guidi sezioni di fe, lnl, mib (como e ts)...
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NTA-HCCC
Stato aggiornato della sperimentazione
Vincenzo Guidi
Sezioni di FE, LNL, MIB (Como e TS)
Partecipazione esperimento UA9– CERNCoordinato da W. Scandale
2
5
3
1
4
6
Outlook
Sample preparation
Runs with negative charges (H4)
Runs with positive charges (H8)
Connection with UA9 experiment
Activity under way in 2009
Demand for lower roughness
An application of crystals would be the collimation of beam halo in next generation of hadron machines (e.g. the LHC)
Particles in the halo drift outwards at the rate of ~2 nm per turn. Since the tune is not integer, the particles will hit the crystal every ~10-20 turns and thereby the first impact parameter of the particles onto the crystal will be in the range of ~100 nm (curtesy of V. Previtali and R. Assmann)
It demands a crystal with a roughness lower than 100 nm on the lateral faces of the crystal
Anisotropic etching I
Anistropic etching is a feasible way to realize sub-surface damage free crystals entirely by wet chemical methods
(100) (110) (111)
7.1 m/h 10.7 m/h Negligeable
Etch rate on different silicon planes for KOH 20% at 40 °C
Photolythography
a) Starting material: (110) silicon wafer
b) LPCVD deposition of silicon nitride thin layer
c) Silicon nitride patterning
d) Etching of Si in KOH solution, silicon nitride acts as masking layer
e) Silicon strips release
f) Removal of silicon nitride
Fabrication of multistrips
Fabrication of either a multistrip or a batch of strips is possible through wet chemical methods
Structural characterization
Lateral surface (AFM)
Sub-nm roughness was achieved
Entry surface (HRTEM)
High-quality surfaces achieved via ACE
Sub-nm roughness was
achieved
Previous runs
August and September data acquisition setup for 400 GeV/c protons and 150 GeV/c µ-, π- , K-
1.92x1.92 cm2 telescopes with reading steps 50 µm
Spatial resolution:5 µm
DAQ rate = 2.1 kHz
Goniometer
Perpendicular planes orientation(to looking for axial channeling)
Stage rotativo “culla”
goniometer
crystal
Vertical direction
Bended planes orientations(to looking for planar channeling)
Axial channeling
First observation of axial channeling with high efficiency.
Capability to divert 90% of beam particles towards an ordered direction
Negative particles I
First observation of:• planar channeling
• volume reflectionwith negative particles
Negative particles II
First observation of axial channeling with negative particles in a single strip
P(θx>0)=90.6%
MST14 Multistrips I
• 12 crystals aligned in ~400µm
• ~40µm volume reflection region with:
-no channeling-109µrad deflection angle
New crystal holder conception
MST14 Multistrips II
• 12 crystals aligned in ~100µm
• ~160µm volume reflection region with:
-no channeling-109µrad deflection angle
Different mass charge distribution over strips
MST14 Multistrips III
Volume Reflection
• Deflection angle:
109 µrad
• Efficiency:
94%Surprisingly
high level
MVR 2007 vs 2008
2007 2008
MVR 2007 vs 2008
Deflection angle: 40.5 radEfficiency: 93%
Deflection angle: 109 radEfficiency: 94%
MST curvature dependence
Volume Reflection:Deflection Angle VS Radius
Channeling:Efficiency VS Radius
MST15 Multistrips I
• Low efficiency channeling peak
• ~400 µm volume-50µrad deflection angle
Changed bending angle
MST15 Multistrips II
• No channeling peak
• ~750 µm volume-25µrad deflection angle
Changed bending angle
Multiple volume reflection in a single crystal
Volume reflection from different planes
Clear observation of multiple volume reflection in single strip crystal (V. Tikhomirov, PLB 655, 5-6, 2007)
Schemes for beam collimation
Planar channeling (ST9 for UA9)
Volume reflection (MST14 for UA9)
Axial channeling
Multiple volume reflection in a single crystal
The steering committee of the UA9 selected two crystals fabricated by
INFN
Scientific production
NIM B 249 (2006) 302
PRL 97 (2006) 144801
NIM B 252 (2006) 11
APL 90 (2007) 114107
APL 91 (2007) 061908
PRL 98 (2007) 154801
PLB 658 (2008) 109
RSI 79 (2008) 023303
PR ST 11 (2008) 063501
JPD 41 (2008) 245501
PRL 101 (2008) 164801
PRL 101 (2008) 234801
PRL 102 (2009) to appear
PRA 79 (2009) to appear
PRL 102 (2009) to appear
2009 Activity I
External line H410 days
Negative particles (µ- and π-) beam 150 GeV/c
Electron beam 150 GeV/c
External line H838 days
Proton beam 400 GeV/c
2009 Activity II
Planned experimental activity on H8
1. Investigation on multiple volume reflection
2. Observation of multichanneling (with piezo-systems)
3. New material (Tungsten)
4. New concept: silicon lens for channeling experiment
5. Observation of PXR with 400 GeV protons
2009 Activity III
Planned experimental activity on H4
1.Precise measurements of dechanneling length
2.Study of multiple volume reflection with negative charges.
Super-acceptance channeling I
With a silicon lens it is possibile to reduce the number of dechanneled particles by focusing the proton beam onto the center of the potential well, with a precise cut in the crystal
beam
cut
crystalz1
z2
z3
0
x
y z
Super-acceptance channeling II
Simulation of particle trajectories
Silicon crystal Silicon Lens
Super-acceptance channeling III
Channeling with focusing results in 99% efficiency!
0,0 0,2 0,4 0,6 0,8 1,00
5
10
15
20
25
30
θ
Pdech
, %
rms, μrad
7 TeV
0 1 2 3 4 5 6 70
5
10
15
20
25
30
35
40
θ
Pdech
, %
rms, μrad
400 GeV
,1
,71
,17
3
2
1
cmz
mz
mz
===
μμ
,1
,14
,4
3
2
1
mmz
mz
mz
===
μμ
Super-acceptance channeling IV
Implementation of the method of the cut through a buried SIMOX layer
Richiesta di integrazione
ME Inv
FE 4.5 16
LNL 2
MIB 4.5