The ”mature” target (2000-2005)
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Transcript of The ”mature” target (2000-2005)
P. Lenisa 1
The ”mature” targetThe ”mature” target(2000-2005)(2000-2005)
P. Lenisa – Università di Ferrara and INFN
Hermes End of Data Taking - Hamburg, 01.07.07
P. Lenisa 2
Data taking:Data taking:longitudinal runlongitudinal run
P. Lenisa 3
Deuterium 2000Deuterium 2000The “wonder” targetThe “wonder” target
• No T dependence of and Pa
•No recombination
•No wall depolarization
(SEC negligible)
• 8 months of perfect running
•HERA (no beam dumps)
•HERMES (no vacuum breaks)
•TARGET (no hardware failures)IDEAL target → no drawbacks from use of storage
cell
P. Lenisa 4
Measured in the polarimeter
Avera
ge v
alu
e in
th
e
cell
The enemies of a bad cell:The enemies of a bad cell:Sampling correctionsSampling corrections
P. Lenisa 5
Measured in the polarimeter
Avera
ge v
alu
e in
th
e
cell
The enemies of a bad cell:The enemies of a bad cell:Sampling correctionsSampling corrections
No recombination and no depolarization
“The polarization we measure is exactly what the beam sees”
P. Lenisa 6
The beauty secret: waterThe beauty secret: water
• Excellent initial performance
• Improved with aging thanks to D20 covering
P. Lenisa 7
2003 reanalysis of 1997 hydrogen 2003 reanalysis of 1997 hydrogen datadata
“Now we understand our target”“Now we understand our target”
• 4 different data periods
• Use of limit for sampling corrections
• Use of measured value for molecular polarization (=Pm/Pa)
P. Lenisa 8
Summary of target performance.Summary of target performance.Longitudinal running.Longitudinal running.
Target/year H||(1997) D||(2000)
Pt 0.851 ± 0.033 0.845 ± 0.028
r 0.055 0.003 (absent)
PSE 0.035 ≤0.001 (absent)
PWD 0.02 ≤0.01 (absent)
PBI - -
t(1014 nucl/cm2)
0.7 2.1
FOM (P2t) 0.5 1.5
P. Lenisa 9
Data taking:Data taking:transverse runtransverse run
P. Lenisa 10
Fourier analysis of e-bunch:–Resonance condition:
n
fi
h
EE
Depolarization
Longitudinal holding field
Transverse running: Transverse running: beam induced depolarizationbeam induced depolarization
P. Lenisa 11
Transverse running: Transverse running: beam induced depolarizationbeam induced depolarization
Transverse holding field
P. Lenisa 12
Field intensity: 297 mT– B along z: 0.05 mT– B along y: 0.18 mT– B along x: 0.7 mT
(requested: B 0.15 mT)
Transverse magnet Transverse magnet
P. Lenisa 13
Cell correction coilsCell correction coils
P. Lenisa 14
Hydrogen 2003/04Hydrogen 2003/04The “hidden” beautyThe “hidden” beauty
• No recombination
• Minimal depolarization for an H target
• Target reached the FOM limit
P. Lenisa 15
Period 10/2003-03/2004
04/2004-07/2004
01/2005-04/2005
04/200511/2005
cell1 1 (warm-up) 2 3
Pt 0.786 ± 0.036
0.721 ±0.059
0.62 ±0.09
0.73 ±0.06
r absent absent 0.24 0.035
PSE 0.055 0.055 0.055 0.055
PWD 0.055 0.12 0.17 0.12
PBI ≤0.01 ≤0.01 ≤0.01 ≤0.01
t(1014nucl/cm2)
1.1 1.1 1.1 1.1
FOM (P2t) 0.7 0.6 0.4 0.6
Summary of target performance Summary of target performance Transverse running.Transverse running.
P. Lenisa 16
The cherries on theThe cherries on the (target) cake… (target) cake…
P. Lenisa 17
Measurement of polarization of Measurement of polarization of recombined moleculesrecombined molecules
• Recombination on cell walls
• Impact on target polarization
• No measurements existing on recombination on an insulating surface (like Drifilm)
• Delicate measurement of surface physics
P. Lenisa 18
Tcell set to 260 K
(recombination increased)
Measurement’s principleMeasurement’s principle
=Pm/Pa
P. Lenisa 19
ResultsResults
HERMES = Pa/Pm= 0.68±0.09stat±0.06syst
Pm=Pa=0.34±0.22 -> atoms on Drifilm surface are polarized (r ~ 14s)
P. Lenisa 20
First measurement of the spin-exchange First measurement of the spin-exchange collision cross-section in the low collision cross-section in the low
temperature regiontemperature region
• Spin-exchange collision:
two body process in which two atoms exchange their spins (conserving total angular momentum)
• Control of the cell temperature allows for variations of atomic gas temperature
• HERMES target unique tool for precision measurement of atomic polarization
P. Lenisa 21
• Pz+ injected (|1>, |4>)
spin-exchange collision |4> → |2> (Pz)
• Pz- injected (|2>, |3>)
spin-exchange collisions |2> → |4> (Pz)
↓spin exchange collisions
cause nuclear depolarization of the sample (Pz)
A measurement of Pz gives access to SE
Measurement’s principle IMeasurement’s principle I
P. Lenisa 22
• Two depolarization mechanisms active in the cell
•Wall depolarization (density independent)
•Spin-exchange (density dependent)
Measurement’s principle IIMeasurement’s principle II
Decoupling of the two effects by intensity variation of the atomic beam
Pz=Pse
Pz=Pse
)21(
)1(2 2
sed
sese PnL
xP
P. Lenisa 23
HERMES data
ResultsResults
P. Lenisa 24
Numbers…Numbers…
P. Lenisa 25
Years Target DIS (Milion) Polarization
1996-1997 H|| 3.5 0.851 ± 0.033
1998-2000 D|| 10.2 0.845 ± 0.028
2001-2005 H ~6 0.74 ± 0.06
DataData
Best existing world sample
Only existing world sample
P. Lenisa 26
Label No. Size Installed Last
3 1 29.8x9.8 04/96 12
4 2 “ 04/97 5
4 2 ” 12/97 4
5 3 “ 08/97 5
6 4 “ 04/98 11
8 5 19.8x8.0 01/99 1
7 6 29.8x9.8 02/99 9
11 7 “ 10/99 1
13 8 21.0x8.9 11/99 11
Fe1 9 “ 05/01 9
Fe2 10 “ 01/02 16
Fe5 11 “ 05/03 18
Fe6 12 “ 09/04 8
Fe4 13 “ 04/05 8
• 13 cells used • 9 months average last (1 min, 18 max)
• 20 produced• 50 man-months
CellsCells
The “innocent” victim
P. Lenisa 27
RecordsRecords
2004
5 broken dissociator tubes
1999
4 beam dumps
(Total: 9 bad dumps)
P. Lenisa 28
• 10 PhD thesis
• 7 diploma thesis
• 3 Collaboration papers
• 7 dedicated target papers
• (3 possible additional papers)
PapersPapers
P. Lenisa 29
B. Braun, C. Baumgarten, I. Brunn, M. Capiluppi, V.Carassiti, G. Ciullo, G.
Court, P. Dalpiaz, D. Fick, A. Golendukhin, E. Garutti, G. Graw, W.
Haeberli, M. Henoch, R. Hertenberger, N. Koch, H. Kolster, H. Marukyan, R. Mussa, A. Nass, S. P. Pod’yachev, M.
Raithel, D. Reggiani, K. Rith, C. Simani, E. Steffens, J. Stenger, J.
Stewart, P. Tait, S. Tessarin, S.Wang, H. Ye, Y. Ye, T. Wise
22 senior physicists
10 PhD students
7 Diploma students
Manpower (1996-2005)Manpower (1996-2005)
(> 70 man years)
P. Lenisa 30
Target awardsTarget awards
P. Lenisa 31
The best piece of artThe best piece of art
02.03.02 – TGA chamber opened after 8 years of operation
P. Lenisa 32
The most original DESY aquariumThe most original DESY aquarium
07.02.03 – ABS flooded (50 liters of water)
P. Lenisa 33
The most insane (realized) The most insane (realized) suggestionsuggestion
19.05.04 – 1680 minutes of uninterrupted TGA chopper wheel observation
P. Lenisa 34
The biggest pig which entered East The biggest pig which entered East HallHall
15.08.05 – Spin and pork seminar
P. Lenisa 35
15.08.05 – Spin and pork seminar
The biggest pig which entered East The biggest pig which entered East HallHall
(dead)(dead)
P. Lenisa 36
The most courageous (crazy?) The most courageous (crazy?) intuitionintuition
“We will install an polarized internal target in HERA (with a storage cell) and measure its polarization with
3% absolute error”
Beginning 1988:
P. Lenisa 37
but up and running for but up and running for PAXPAX
(since 21.05.07)(since 21.05.07)
P.S.P.S.The HERMES target is not dead…The HERMES target is not dead…