Download 2016.11.20, LHC-type Crystal Dossier, QMP52 (v1.5 - Indico

Datasheet QM52 (v1.3)
[Type text]
2016.11.20
Datasheet
QMP52 crystal
Crystal assembly description
QMP52 is a crystal assembly (Figure 1) designed for investigations in the frame of Crystal
collimation experiment (UA9). The crystal assembly consists of metal bending device and silicon crystal
bent inside of bending device with means of quasi mosaic effect. The main purpose of crystal assembly is to
deflect charged particles hitting outer part of crystal by means of channeling effect. It has been designed for
the installation into the high precision goniometer for the crystal collimation research of high energy halo
particles circulating in the LHC. The design of bending device has been developed in PNPI (Gatchina) to be
assembled without any single screw in order to effectively resist against thermal shocks for long term
stability.
Crystal parameters
y
Dimensions:
z
Full assembly
Height (y)
mm
Width (x)
mm
Length (z)
mm
Total weight
g
Crystal
Height (y)
mm
Width (x)
mm
Width of outer part
mm
Length (z) / along the beam
mm
Crystal characteristics:
Planar channeling plane
Miscut angle for channeling
Defection angle
Efficiency of deflection
(protons 400GeV/c)
urad
rad

40 ± 0.05
29.6 ± 0.1
25 ± 0.1
95.75 ± 0.01
x
27 ± 0.02
30 ± 0.02
6.5 ± 0.1
4 ± 0.02
(111)
25 ± 10
55 ± 3
69 ± 3
Date of final assembly: 2015.06.05
Figure 1. QM crystal of LHC-type
Bending device
The bending device consists of five (5) metal parts bending one silicone crystal. The four metal parts
made of Titanium alloy Grade 5, one part made of Beryllium bronze (see the list of materials below).
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Datasheet QM52 (v1.3)
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2016.11.20
All the titanium parts have passed through the standard thermal annealing process at 700°C in order to
release possible mechanical internal tensions induced by manufacturing of raw material. This operation is
obligatory for components critical to long term stability of shape.
The assembly doesn’t contain screws or adjustable elements, it keeps the bending of crystal by means
of internal spring and capable to be heated up to 300°C.
All the parts have been manufactured with the following treatments: milling, grinding, deep optical
polishing. One part after polishing has been coated by high reflective nickel-molybdenum alloy in order to
provide flat reflective surface which is used for optical alignment of crystal mounted into goniometer.
The crystal with bending device has been assembled on June 5th 2015 following with measurements of
bending angle with H8 test beam in CERN.
List of Materials
●
●
●
●
Spring - Beryllium bronze CuBe2 (known also as Alloy 25, C 17200);
Bending device (4 parts) - Titanium alloy Grade 5 (known also as Ti-6Al-4V), it is a chemical
composition of Titanium with 6% of Aluminum, 4% of Vanadium, 0.25% (maximum) of Iron, 0.2%
(maximum) of Oxygen;
Crystal – monocrystalline silicon;
Round mirrors - Nickel-Molybdenum non-magnetic alloy sputtered on titanium optical polished
surface. The mirror has a round shape of diameter 11 mm and thickness ~2.7 𝜇m.
Heating test
Crystal assembly was treated with the heating test at vacuum lab in b.SMA18 performing the thermal profile
with the following characteristics: heating under vacuum < 10-5 bar at temperature 250°C during 24 hours
with ramp up/down 50°/h.
The heating test of QMP52 was performed 2 times with characterization by means of H8 beam before and
after heating:
- 8th June 2015 in the vacuum lab of b. SMA18;
- 4th July 2016 in the vacuum lab of b. SMA18.
Crystal characteristics
While manufacturing during February-May 2015 crystal assembly was passed through multistage process of
grinding and deep polishing of all the surfaces with the control of orientation of working crystal planes (111)
with respect to the crystal face. Miscut angle of crystal represents a misalignment between optical surface of
working face and (111) crystal planes. At the final production stage the miscut angle was characterized by
means of X-rays diffractometer and resulted to be better than 50 rad with the following deep polishing. The
miscut angle of assembled crystal device was measured with X-ray setup in 2016 with result 25 ± 10 rad.
During manufacturing and preliminary assembly crystal bending angle was characterized at PNPI by indirect
optical methods based on measurement of primary bending curvature by means of profilometer based on
while-light interferometry principle and custom developed equipment for characterization of optical surfaces
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Datasheet QM52 (v1.3)
[Type text]
2016.11.20
shape known based on deflectometry. After final assembly the crystal bending features were characterized
by means of direct method on H8 test beam of protons with the energy 400 GeV/c and later with pions 180
GeV/c. The measurements were performed before and after heating without additional optical indirect
characterization after beam tests.
The deflection angle of crystal by means of channeling effect is described as a difference between incoming
and outcoming trajectories of charged particles hitting crystal in the oriented conditions. This kind of
deflection is characterized also by channeling efficiency which is the fraction of deflected particles with
respect to flux hitting crystal in the selected geometrical region on crystal. The torsion of crystal is the
changing of crystal plane orientation vs. vertical impact position.
The following Table 1 represents direct measurements of deflection angle and channeling efficiency
performed for crystal QMP52 with test beams. The respective results of characterization are also show on
Figure 2and Figure 3.
Table 1. Results of crystal characterization
#
Conditions
Date
1
before heating 2
2015.06.06
2
after heating 2
2015.06.13
3
before heating 3
2016.07.01
4
after heating 3
2016.07.05
5
after heating 3
2016.09.16
Beam
Deflection
angle
400 GeV
proton
beam
400 GeV
proton
beam
180GeV
pion beam
180GeV
pion beam
180GeV
pion beam
3
rad
54.3 ± 2.5
Efficiency
(±5 rad beam
divergence)
%
67.7 ± 3.5
Torsion
(±2mm in
vertical)
rad/mm
<1
55.0 ± 2
69.7 ± 3
<1
57.8 ± 3
66.3 ± 4
-
55.4 ± 2
64.8 ± 4
-
54.5 ± 3
65.8 ± 4
-
Datasheet QM52 (v1.3)
[Type text]
2016.11.20
70
Deflection angle, rad
Protons 400 GeV/c
Pions 180 GeV/c
June 2015
65
July 2016
Sept. 2016
60
55
50
45
bakeout 2
bake-out 3
40
1
2
3
4
5
Test #
Figure 2. Measurements of crystal deflection angle
85
Protons 400 GeV/c
Deflection angle, rad
80
Pions 180 GeV/c
June 2015
July 2016
Sept. 2016
75
70
65
60
55
bakeout 2
bake-out 3
50
1
2
3
4
5
Test #
Figure 3. Measurements of crystal efficiency deflection
4