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Title: Beam Line Status

1
Beam Line Status
MEG-Review February 2006
2
Measurement Synopsis

2005 (post last Review) 2 Beam periods
mid July end August
? BTS arrival Commissioning
(for technical reasons only dewar
operation possible)
? Bfield mapping
? Phase Space measurements up to end BTS
misalignment sensitivity observed ?
design steering magnet
beg. November end December
? Commissioning BTS with PSI LHe Cryo-plant
BTS Control systems
aim to achieve automated BTS
operation
? Injection Phase Space measurements
inside COBRA
temporary He-Bag system for COBRA
3-D measuring machine
APD new horizontal steering
magnet implemented

3
Beam Line Status

All beam elements functioning
- BTS stable in automatic mode
- Separator now stable
- improvised He-Bag for COBRA constructed
tested
- horizontal steering magnet manufactured
installed
Beam Line Commissioning Phase 1 part Phase 2
finished
(rest Phase 2 2006)
- First beam injected into COBRA measurements
with all Bfields ON
COBRA end-caps/He-Bag System - design close to
completion
- US End-Cap fully designed (apart from Burst
valve system)
- DS End-Cap, same as US apart from central
part for Insertion System, (awaiting
completion of Insertion Tube System design)
Insertion Tube System
design study underway
Target System
Discussions with Bill (UCI) Makisan (KEK) about
3 potential designs also UCI expressed interest
in taking-over the target design/manufacture
agreed on, though in coordination with PSI (beam)

4
Measurement Schedule Nov.-Dec. Beam Commissioning

First Time Operation
of BTS with LHe-Cryo. Plant
4 weeks (2-planned)
to cool-down
have stable
AUTOMATIC
OPERATION
(thanks go to Cryo. Group Stefan)
5-days lost Separator
Repair

5
Nov.-Dec. Measurement Programme
Measurements with Degrader DC-test Not
possible ? 2006
?
?
?
?
?
?
?
6
COBRA Injection Test Setup
LHe From Cryo. Plant
CH2/EVAL/CH2 sandwich
BTS-COBRA Improvised Connection He-Bag US
Improvised He-Bag DS
7
Phase Space Measurements
Magnet measuring machine
APD
COBRA DS without He-Bag

Measurements performed in COBRA
excitation curves like - unlike --
polarities
beam profiles rates at centre both polarities
SNM, DNM
for ? 0, 180, 30, 45, 60
axial z-scan over whole COBRA length
profiles at various z-positions
Present priority end-cap
design
Detailed Analysis of Nov./Dec. data to be
started shortly

8
Provisional Results Centre COBRA
COBRA Axial z-scan (No Degrader)
Very similar to GEANT Predictions
BTS-Excitation Curve to focus beam in COBRA
unlike - Polarity
Measured Rate at Centre COBRA (Dependent on
mode) Rµ (1.15 - 1.19)108 µ s-1 at 1.8mA 4
cm Tg.E
9
Provisional Results Centre COBRA cont.
COBRA Horizontal Vertical Beam Profiles In
100He No Degrader
GEANT 90 He 10 Air
? 12.8 mm
Reality
? 13.5 mm
Theory GEANT
Reality

?
Investigating misalignment asymmetry for BTS
/- focusing
!!! Varies with mode ? up to
10 mm off centre !!!
re-measure BTS radial symmetry during COBRA /
BTS field mapping
magnetic axis geometrical axis
???

10
Sonic Resonance Gas Concentration Monitor (SRGCM)

Developed during Nov./Dec. run
flush COBRA exhaust gas through pipe length L
use frequency generator, speaker microphone
to create standing wave in pipe
measure resonant frequency overtones ?
determine SPEED OF SOUND in GAS
compare to pre-calibrated curve of SPEED of
SOUND vs. HELIUM CONCENTRATION

2L?fij i (j1)
or
L ?fii jj ii ( jj2)

1st resonance 2nd resonance 3rd
resonance 4th resonance
With systematics under control
refinements Absolute precision lt lt 0.5 achievable
Frequency
COBRA measurements gave (91.6 0.2) He rest
Air
He-Concentration
11
Setup
Gas-Rack
Frequency Generator
Oscilloscope
Pipe (88.6cm)
Air
Microphone
Speaker
Helium
12
COBRA End-Cap Flanges Insertion System

Based on extensive background studies (Kenji)
Permanent Rohacell insertion tube rejected for
fixed ?-target (with rotation/translational

possibility)
retractable insertion bellows system for
accelerator, LH2-target beam monitoring
future insertion possibilities

e.g. US End-Cap Flange DS-version
Mounted after DCs US-TCs

Upstream End-Cap Design finished
apart from rupture valve
system
deadline for completion mid-Feb.
Downstream End-Cap very similar to US
apart from central region for Insertion system
DC cable/gas feedthroughs
finalization of design depends on completion
of insertion system design
deadline for completion mid-March.

13
Rupture Valve System
Diminish damage to COBRA environment (mainly DCs)
due to rupture of beam vacuum window (Prob.
2/30 yrs)

Simplified Calculation based on
Bernoullis Equation
Darcy-Weisbach Equation for
turbulent flow
Colebrook-White approximation for
frictional factor Moody diagram
conservation of mass
Possible to approximate flow conditions
after rupture
ignoring SHOCK WAVE !!!

V3
V3
Vacuum V1
He V2
V3

No Rupture Valves
Depressurization time 10 ms
streaming velocity in vac. 660 m/s
Reynold number 1.4106 (turbulent gt4000)
?PCOBRA 446 mb
?TCOBRA 63 K

14
Rupture Valve System cont.

With Rupture Valves max 4 US 4 DS
re-pressurization time 890 ms/ 1 burst valve
pressure compensation for 8 valves in 10 ms
20 mb/ 10 ms
Conclusion with 8 Valves dMAX 6 cm
ONLY 5 compensation !!!

Spring-loaded Hinged Sealing flap
Inside He
Outside air

Reality must consider
SHOCK WAVE enhanced by He
generated into vacuum pipe
reflection 10 ms also

Contact Surface 979 m/s
COBRA
Shocked air
vacuum
shock front 1175 m/s
Expansion front 1000 m/s
Expansion tail 933 m/s
Conclusion need a faster acting system !!!
Not Solved new idea
15
Insertion System