Beam Transport

1
Beam Transport Target Systems
BTS Success Novosibirsk 24/5/2005 1815 300 A
2
Beam Line Target Status

• Topics to be Addressed
• Beam Transport System
• (i) Degrader / BTS optimization
• (ii) Layout - fixed
• Beam Line Components Status
• (i) Separator- undergoing
  HV-conditioning
• (ii) Beam Transport Solenoid BTS
  being commissioned ?E5
• (iii) Vacuum System (beam line BTS)- being
  assembled
• (iii) Cryogenic Transfer Lines LN2 LHe
  installed
• He-Bag Target Systems
• Schedule 2005
• Summary Critical Points

3
Beam Transport System Status
4
Beam Transport System
As previously reported Beam Line
Commissioning 2004 concluded with phase space
measurements In vacuum up to the INJECTION into
the BTS (without BTS !!!)
Using real data ? SIMULATE Phase Space
Back-Track to Triplet II
? Forward-Track with Fringe Field of BTS
COBRA up to Target in COBRA

using GEANT
waist
Input Data to GEANT to study Degrader/Target
BTS/COBRA layout
5
Degrader BTS/COBRA Optimization

• Studied
• BTS/COBRA Distance vs. Degrader segmentation
  Bfield
• (Cryo.-Cryo. Gap) minimum (200 mm),
  intermediate(300 mm), maximum(400 mm)
• BTS/COBRA Polarity (/), (-/) radial
  de-focussing/focussing

Max. Bve
Gap ?
Max. B-ve

• Weak Gap dependence (4)
• strong polarity dependence
• (15)

• Gap 400 mm
• -/ Polarity
• Degrader BTS

• strong degrader segmentation
• dependence (25)

6
Beam Transport System Layout
Distances Fixed Platform COBRA surveyed into
Zone
7
Beam Line Component Status
8
Component Status Separator

• MEG Vertical Separator
• Delayed by 8 weeks
• due to HV feed-through problems now solved
• HV (ve) supply changed to (ve) one - technical
  
• HV-electrode on top, want e deflected
  down
• !!! HV Conditioning Tests in front of ?E5
  !!!
• expected ready for beam time

Beam Upstream Side
Properties Vmax 200kV Dplates 19cm Leff
70cm
2371 mm
April 2005
May 2005
June 2005
9
Component Status BTS

• Beam Transport Solenoid BTS
• Schedule delayed by 7 weeks
• 5 weeks delay during manufacture
• 2 weeks transportation (papers stolen at
  Russian border)
• nevertheless
• !!! Novosibirsk Crew did a Very Good Job
  !!!
• BTS arrived PSI 8th July

Coil Manufacture - epoxying
Performance Tests Novosibirsk
End March 2005
End May 2005
10
BTS Performance Tests - Novosibirsk

• Performance Tests
• BINP Novosibirsk 21-29th May 2005
• Tested
• maximum Design Current (300 A)
• Quench Detection / Protection Systems
• (fast switch 30 ms 0.7? Shunt Resistor 90
  power load)
• Linearity Response (max. dev. 0.4)
• LHe Consumption Rate (3.6 l/hr)
• Magnetic Field Measurements

• Flexible Cryogenic Design via
• dedicated transfer lines (PSI)
• dewar operation (BINP)
• both (emergency)

All measurements tests successful
except Bfield measurements which were
influenced by steel support
structure
0.7? Shunt Resistor
11
Results BTS Performance Tests - Novosibirsk
Main Specifications LCryo 2810 mm DBore
380 mm DCoil 469.5 /
466.2 mm LCoil 2630 mm BMax
lt0.55 T Imax 300 amps LMax
0.98 H EStored 44 kJ

• Coils
• double layer
• cable dia. 1.23 mm
• 1865 / 1980 windings
• 40 NiTi
• RRR 100

BTOT deviates from expected due to Steel support
structure !!! Needs to be re-measured at PSI
!!! Acceptance Tests
Linearity (B vs. I) better 0.4 up to 300 A
12
BTS Preparations PSI

• Preparations for BTS Installation in
  ?E5
• cryogenic lines for LHe LN2 ready for
  connection
• valve chamber ready for mounting on BTS
• power supply tested ready

Valve Chamber Couples BTS to LHe transfer Line
contains Joule-Thompson Valves for control
LHe Transfer Line
Refrigerator unit Above ?E5
LHe line
13
BTS arrival PSI
8th July 2005
14th July 2005 ?E5

• BTS arrival PSI
• 8th July
• Acceptance Tests
• assembly / survey ?
• vacuum / leak tests ? ?
• cryogenic installation ?
• electrical installation ?
• cool-down
• quench detection /
• protection tests
• Bfield measurements

On route PSI 6500 km Novosibirsk - PSI

• !!! Problems !!!
• welding joint tower / cryostat
• damaged in transport
• ? Re-welded OK
• cryogenic connection valve-
• chamber / LHe transfer line
• not compatible
• ? To workshops
• Use dewar system LHe

Dmitry Reports 18th July 1100 coil
superconducting 2000 283A reached
(nominal 200A)
On route ?E5
14
He-Bag Target System Status
15
He-Bag / Target System - General

• (I) Desired Beam
  Characteristics
• transport maximum number µ to the target
  (vacuum / He, large ?P)
• maximize µ stopping-rate in the target
  (small ?P, vacuum /He)
• minimize beam spot size multiple
  scattering (vacuum / He, degrader close to
  target)
• minimize background from decays or
  Bremsstrahlung (degrader far from away, vacuum /
  He)
• (II) Desired
  Target Requirements
• depolarizing target (isotropic e, non-metal)
• minimum target size (low-Z)
• minimize material traversed by decay e ?
  (slanted target)
• minimize generation of annihilation photons
  (large X0, low-Z e.g. CH2)

?
?

• Consequences
• vacuum window interface to COBRA
• He-atmosphere inside COBRA
• slanted, non-metallic, low-Z, large X0 target

16
COBRA-Environment

• (III) COBRA Environment
  Requirements
• thin vacuum window at entrance COBRA (190µ
  Mylar)
• safety measures against vacuum window rupture
  (safety seals !!!)
• must maintain DC TC dimensions insertion
  concepts
• stringent constant differential He-pressure
  between DCs COBRA (few µb)
• no He-leakage to TC PMs (N2-Bag)
• frequent / less frequent access to Downstream
  side for calibration
• monitoring purposes (
  e.g. Cockroft-Walton, ?- CEX)
• possibility to exchange targets ( LiF, LH2, CH2
  etc.)

• Consequences
• Thin beam line Vacuum Window
• COBRA End-Cap Flanges HE-seals (US,DS)
• Target Insertion Tube support
• system (separate He-environment) (TISS)
• Target System (TS)
• ?
• PSI staged Engineering Design Project
• started design construction
• (i)US-flange, (ii) DS-flange, (iii) TISS, (iv)
  TS
• design Construction ready Feb. 2006

17
End-Cap Flanges He-Bag seals
Engineering Design Concept Upstream End-Cap

• Design
• Allows open
• access to TCs
• withdrawal
• without affecting
• He-environment
• Mounting
• N2-Bag
• TC-rails
• End-Cap
• He-Bag
• TCs
• Beam pipe
• with BTS
• Couple He-
• Bag rings to
• vac. window

He-Bag composition Sandwich CH2/EVAL/CH2
He-Bag inner sealing rings
18
Target Optics - momentum
Momentum-Spectrum Data whole Beam Line
optimized for each data point 2-D Scan for
each point !!! Theory ?-Kinematic Edge (29.79
MeV/c) Theoretical func. P3.5 folded with
Gaussian ?P/P Const. Cloud µ contribution ?
Fitted to data
Goal maximize stop-density (min. target
size) Question optimum beam momentum? Answer
28.2 MeV/c

• ? range vs. P
• (fixed ?P/P 7.7 FWHM)
• straggling 11
• characteristic P3.5

P3.5
straggling 11
Rel. ? stops

• ? Stopping Rate vs. P
• (fixed ?P/P 7.7 FWHM
• fixed 400? CH2 target)
• as p gt relative stop rate lt
• as p gt beam rate gt
• Optimal Stop Rate
• at P28.2 MeV/c

Norm. ?-stops
?2/dof 0.94 Pcent (28.16 ? 0.02) MeV/c ?P/P
(7.7 ? 0.3) FWHM Pbeam (28.2 ? 0.9)
MeV/c
P3.5
19
Target Optics - degrader
Many solutions studied 2 main categories
BTS
DMN

• (1) DNM Solution
• (190? Mylar Window)
• BTS / COBRA unlike
• polarities
• BBTS -3.55 kG
• degrader 480? CH2 at
• centre BTS
• beam ? 12.5 mm

COBRA
BTS
?P 4.2 MeV/c
? Beam envelope (cm)
?P 2 MeV/c
?P 4.5 MeV/c

• Transmission
• Efficiency
• TBTSDeg 98
• TBTSdegCOBRA 88
• TSepTIIClli 86.5
• Expected Stopping Rate
• R? 9.6107 ?/s
• at 1.8mA 4cm Tg
• (1.7108 ?/s at 1.8mA 6cm Tg)

Momentum Profile (MeV/c)
BTS
COBRA
? Beam divergence (mrad)
20
Target Optics degrader cont.

• (2) SNM Solutions ( no
  degrader in BTS)
• 
  (125? Mylar Window)
• either combine Degrader Target (asymmetric
  stop distribution)
• or move degrader slightly upstream of target
  (e.g. use as end-wall of target insertion tube)

• Conclusions SNM (no BTS degrader)
• Combined Soln gives ? 10 mm for 125? Mylar
  Window
• with 190 ? Mylar ? 11.5 mm
• no straggling loss only 3 decay loss
• Expected Rate R? 1.06108 ?/s at
  1.8mA 4 cm Tg.
• BUT annihilation radiation potential worse -
  needs to be simulated
• Upstream Soln gives similar results to DNM ?
  12.5 mm
• annihilation radiation potential worse - needs
  to be simulated

upstream Deg. 15 cm
Combined Tg Deg
21
Target Insertion Tube

• Target Geometry ( for beam ? 10mm)
• LPROJ 150.4 mm, ? 21.8, a 60.3 mm, LTRUE
  161.9 mm
• material CH2 Rohacell / Mylar
• Slanted Target must be thicker multiple
  scattering loss
• on downstream-side !!!
• Target Simulation underway
• check of optimum angle ?
• dependence on target thickness (multiple
  scattering,
• background, acceptance, timing, resolution)
• material considerations
• decay particle hit distributions on end-cap
  materials
• associated background acceptance

22
Target Insertion Tube survey

• Target Insertion Tube Support System (TISS)
• Material
• Rohacell (PMI) closed cell foam, maybe EVAL
  foil?
• wall thickness probably 2 mm Rohacell 31
• length 1500 mm
• dia. 150 mm
• ? Weight 51 g
• simulations concerning background from
• e interactions in TISS underway

Target Insertion Tube

• Survey aspects
• target plane determined outside wrt. survey
  markers
• on rohacell support rings (laser tracker)
• possible temporary thin cross-wires on support
  rings
• for axial radial alignment (break
  afterwards)
• radial adjustment made with TISS end-flange
• axial position set by TISS (self-positioning)

?-target system
Flange lateral vertical move- ment
23
Schedule 2005

• Critical Path
• Commissioning Part 1 too short for BTS/COBRA
• phase space measurements ? Dec. Part 2
• final Target measurements ? first beam 2006

• Changes 2005 (compared to previous schedule)
• Separator schedule 8 weeks
• BTS Schedule 7 weeks
• COBRA end-cap target design manufacture
  extended

24
Summary Critical Path

• Summary
• beam transport system up to COBRA defined
• COBRA Platform surveyed into position
• All beam transport elements now manufactured
• MEG Separator being conditioned
• BTS successfully tested in Novosibirsk
  delivered PSI (8th July)
• BTS reached current of 283A during commissioning
  at PSI (18th July)
• All cryogenic lines installed to zone
• all vacuum system available
• engineering project for COBRA end-caps target
  Insertion support system underway
• manufacture to be completed Feb. 2006

• Critical Points
• COBRA phase space measurement delayed until Dec.
  2005 (delays Separator BTS)
• Final measurements with target delayed until
  first beam 2006

25
?-Beam Results (re-cap)
Provisional Results ?- Integral Spot
Rates MHz for 1,8mA Proton Current 4cm Target
E Normalized to Momentum Slit Settings
FS41L/R 250/280 FS43L/R 240/220

• First ?- Beam Studies with MEG Beam
• for calibration purposes in the experiment
• ?-p??0n, ?-p??n
• 55 ? 83 MeV ?s and 129 MeV ?s
• Data taken from
• P-spectrum measurements 25-33 MeV/c
• ?s detected above 30 MeV/c (pulse-ht. RF tof)
• dedicated ?- runs at 56 MeV/c 103 MeV/c
• 56 MeV/c interesting since max. momentum
• that can be transported to COBRA with
• good optics SNM in BTS
• dedicated CEX run at 112 MeV/c

e-
µ-
56 MeV/c R? 7.6 106 ?-/s slits open
R? 7.2 105 ?-/s slits70/70
?-