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Beam Profile Monitor For Slowly Extracted Beams @CERN
Expectations vs. Reality
Signal from 𝟏𝑴𝒆𝑽 electrons is with agreement with theoretical predictions
GEANT4 simulations are needed to better understand the data Next step is a measurement of thinner fibers
(∅ 1𝑚𝑚,∅ 0.5𝑚𝑚)
North Area @CERN
Silica Fiber before and after polishing procedure
• Zero energy loss• Zero beam
perturbation• Radiation hard• Fast• Precise• Cheap
𝒙
𝒙𝟎= 𝟒𝟒. 𝟒𝟕 𝐜𝐦
Radiation Hardness
≥ 𝐌𝐆𝐲
Time resolution ~ns
Spatial resolution
< 1mm
Low cost
Cherenkov Light Detector Based on 𝑺𝒊𝑶𝟐 Optic Fibers
http://bwtek.com/spectrometer-part-6-choosing-a-fiber-optic/
𝒔𝒊𝒏𝜽𝟏 =𝒏𝟐𝒏𝟏
Cherenkov light emission in cone defined by angle:
𝜽𝒄𝒉 Beam direction
𝒄𝒐𝒔𝜽𝒄𝒉 =1
𝒏𝜷
Predicted Cherenkov angle:
beam E 𝜷 𝜽𝒄𝒉𝒆𝒓𝒑 𝟒𝟓𝟎 𝑮𝒆𝑽 𝟏 𝟒𝟕°𝒆 𝟏𝑴𝒆𝑽 𝟎. 𝟖𝟔 𝟑𝟖°
Theoretical angle of beam
For our 90𝑆𝑟 source of 1MeV electrons:
𝟏𝟕° ≤ 𝜽𝒃𝒆𝒂𝒎 ≤ 𝟓𝟗°(±16° from non−colimated source)
PMT
𝑺𝒊𝑶𝟐 fibre
90𝑆𝑟 β − source
Experimental setup
photomultiplier
β - source
Discriminator and counter
module
+
First Results Conclusions and Future investigations
Experimental Setup
Karolina Kmiec, Inaki Ortega Summer Student Session, CERN 2019
𝑆𝑖𝑂2 Fibers𝑆𝑖𝑙𝑖𝑐𝑎 𝑓𝑖𝑏𝑒𝑟
Discriminator and counter module
𝒏𝟐 = 𝟏. 𝟑𝟕𝒏𝟏 = 𝟏. 𝟒𝟔𝜽𝑻𝑰𝑹 = 𝟔𝟗°
Physical phenomena in 𝑺𝒊𝑶𝟐
Perfect Beam Profile Monitor is:
Beam profile monitors are needed to inspect the beam in real time to ensure the required quality. The beams delivered to the North Area are extracted slowly 4.8 𝑜𝑟 9.8 𝑠 , are un-bunched and very intense (1013 𝑝𝑎𝑟𝑡/𝑠). Currently there is no satisfying instrumentation. We investigate the feasibility of a Cherenkov Fiber Detector, which would fulfil all those requirements.
Experimental setup scheme
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RA
TE [
HZ]
BEAM ANGLE [DEGREE]
CHERENKOV LIGHT EVENT RATEVS. BEAM ANGLE
background
data
Total Internal Reflection