K - Tohoku University

NKS2
Upgrade Project
Masashi Kaneta
for the NKS2 collaboration
Department of Physics
Tohoku University
NKS2 in 2005-2007
Deconstruction of NKS
680 Magnet installation
04
gas window (20mm EVAL film)
breaking
FY2005
CDC design
FY2006
FY2007
construction performance repair and
check
check
repair and
check
Analysis
SDC design
construction
IH design
construction frame re-design
and construction
OH
design
construction
EV design
construction
Data taking
LD2 target design, test, construction
Commissioning run
for Tagger and OH
Carbon target run
LD2 target run
• Similar K 0S statistics to NKS
• Now a time to focus analysis and think
about what is the next
Masashi Kaneta, Tohoku Univ.
特定領域研究会於秋保緑水亭 2007/Nov/28
Upgrade Project
• Physics motivation
– K+Y coincidence measurement
• No Fermi motion correction
• Differentials cross section
• Lambda polarization
• Detector upgrade
– Replacing inner detector
• Replace straw drift chamber by a 3D tracker
– increase the acceptance
• Two-side-read-out hodoscope
– increase TOF resolution to have better particle
separation
Masashi Kaneta, Tohoku Univ.
特定領域研究会於秋保緑水亭 2007/Nov/28
L Polarization Measurement
Transverse polarization
measurement
pL
t = pg×pL
qK
pg
Longitudinal polarization
measurement
LCM
pN
q
lab
pL
pp
pK
q
pp
pp
reaction plane
in CM
LCM
Masashi Kaneta, Tohoku Univ.
dN
 N 0 A(cosq ) 1   PL cos q 
d (cos q )
pp
Acceptance
as a function of cosq
特定領域研究会於秋保緑水亭 2007/Nov/28
polarization
decay parameter
0.642(PDG)
Model Predictions: L Polarization
g+n  K 0+L
L Polarization
SA1
(P. Bydzolvski)
KaonMAID
SLA
(rKK=-2.087)
g+p  K ++L
q of Kaon in CM [degree]
Masashi Kaneta, Tohoku Univ.
特定領域研究会於秋保緑水亭 2007/Nov/28
Chamber
Design
NKS2 detectors
• Two Drift Chambers
– Cylindrical Drift Chamber (CDC) and
Straw Drift Chamber (SDC)
• Two Hodoscope
– Inner and Outer Hodoscope (IH and OH)
• Electron Veto
OH
CDC
630 mm
EV
IH
SDC
Masashi Kaneta, Tohoku Univ.
特定領域研究会於秋保緑水亭 2007/Nov/28
• New inner
detectors should
be fit in
630H x f110-400
tube
Detector Alignment
• Current
– IH and then SDC from center
• New detectors
– The chamber and then IH
• Considering rescattering effect
– [S. Kiyokawa’s talk in 2007 Autumn JPS meeting]
– New 3D tracker: Vertex Drift Chamber (VDC)
– Capability of lower momentum tracking
• track of p<75 MeV/c does not reach to OH
– Increasing solid angle
• want to have at least >±45°in vertical
– How large can we have?
– Relating how to set read-out card
Masashi Kaneta, Tohoku Univ.
特定領域研究会於秋保緑水亭 2007/Nov/28
Vertex Drift Chamber Design
•Requirements
– As possible as small cell
• but limited by feedthrough
(f3mm)
– At least 6 layers with stereo
wires
•Decision
– Trapezoid (almost square)
cell shape
– Half cell size: 4 mm
– 8 layers
– uu’ vv’ uu’ vv’
• increasing stereo angle with
radius:6.0 - 11.1°
vv’ uu’
– Drift gas =
Ar:Ethane(50:50)
Masashi Kaneta, Tohoku Univ.
特定領域研究会於秋保緑水亭 2007/Nov/28
vv’
uu’
Chamber Height Dependences
• Simple kinematical calculation
–
–
–
–
generate K0+L events from SLA model
considering Fermi motion for d
taking care decay in flight
not included energy loss and tracking efficiency effect
• Test: Yield as a function of condition
– (a) efficiency for K0S and L, respectively
• No cut, that is, all of K0S+L ( p+p- pp-) events
• Any two tracks pass through OH and two daughters are in the
new chamber acceptance
• Two daughters (from K0S or L) pass through OH
– (b) efficiency for K0S+L event (4 charged tracks)
• No cut, that is, all of K0S+L ( p+p- pp-) events
• Any two tracks pass through OH and four daughters are in the
new chamber acceptance
• Four daughters (from K0S and L) pass through OH
Masashi Kaneta, Tohoku Univ.
特定領域研究会於秋保緑水亭 2007/Nov/28
Current/Future Inner Detectors Position
• Current trigger
– more than two hits on OH && more than two hits on IH && EV
• Track reconstructed
– should have a hit on OH
Liquid Deuterium target holder region
766
OH
712
286
232
VDC
SDC IH
300
IH
78
100 55
65
200
210
1200
Masashi Kaneta, Tohoku Univ.
800
特定領域研究会於秋保緑水亭 2007/Nov/28
630
160
760
17.6º
530
X
CDC
OH
VDC
OH
VDC
OH
VDC
OH
VDC
OH
VDC
OH
VDC
OH
VDC
OH
VDC
OH
VDC
OH
VDC
OH
VDC
OH
VDC
OH
VDC
OH
VDC
OH
VDC
NhitOH≥2
Combinations
of Tracks
4 track
current
4
VDC
trackinevent
Figure of Merit for K 0S and L
(1):
all events
(2)-(6): the two daughters pass
through VDC of which height =
±20,19,18,17,16 cm
(7):
two daughters pass through OH
Any two track hits are required for (2)-(7)
NO decay volume cut (~40(~20)% loss for K 0S(L))
Masashi Kaneta, Tohoku Univ.
L
K 0S
(1)
(2)
(3)
(4)
(5)
(6)
(7)
ratio to (7): FoM
ratio to (1)
• FoM increases about
1% step with
increasing 1 cm step
in VDC height
特定領域研究会於秋保緑水亭 2007/Nov/28
Figure of Merit for K 0S + L Event
L
K 0S
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(1):
all events
(2)-(6): the four tracks pass through
VDC of which height =
±20,19,18,17,16 cm
(7):
four tracks pass through OH
Any two track hits are required for (2)-(7)
NO decay volume cut
Masashi Kaneta, Tohoku Univ.
ratio to (7): FoM
ratio to (1)
• FoM increases about
3% step with
increasing 1 cm step
in VDC height
特定領域研究会於秋保緑水亭 2007/Nov/28
• Acceptance
as a function
of qK
– No drastic
change
FoM
Figure of Merit for K 0S + L Event
four tracks
pass through VDC
(h=19cm)
four tracks
pass through OH
qK in CM [degree]
Masashi Kaneta, Tohoku Univ.
特定領域研究会於秋保緑水亭 2007/Nov/28
Calculation of the Intensity (1)
Distortion
max: 471mm
Safety factor
min: 2.4
• 0.5TH CFRP pipe with hole and 2TH mm board
• end-cap f160, 426 height of pillar
Masashi Kaneta, Tohoku Univ.
特定領域研究会於秋保緑水亭 2007/Nov/28
Calculation of the Intensity (2)
Distortion
max: 456mm
Safety factor
min: 2.5
• 0.5TH CFRP pipe with hole and ] shape pillars
• end-cap f160, 426 height of pillar
Masashi Kaneta, Tohoku Univ.
特定領域研究会於秋保緑水亭 2007/Nov/28
Calculation of the Intensity (3)
Distortion
max:182mm
Safety factor
• 20Lx40Wx0.5TH rectangle CFRP pillar
• end-cap f160, 426 height of pillar
• This design has the most large safety factor
Masashi Kaneta, Tohoku Univ.
特定領域研究会於秋保緑水亭 2007/Nov/28
min: 6.2
Chamber Cross-section
ASD card
for CDC
40
160
65
53
30 20
55
13
165
315
35
pillar
68.7
Inner
Hodoscope
253
190
•ASD cards
will be set in
77 mm height
Masashi Kaneta, Tohoku Univ.
10
7
PMT
62
50
– Wire height =
38 cm
15
105
72
•Considering
space for ASD
card
10
Magnet pole
62.5
a surface made
from wires 特定領域研究会於秋保緑水亭 2007/Nov/28
200
Summary
• The detector upgrade project is on going
– Goal: K+Y coincidence measurement
– Increasing acceptance of tracking
– Increasing start time resolution of TOF
• better p/K/p separation toward K++Y measurement
• Vertex drift chamber
– Design and specification is fixed
• Rectangle cell
• uu’vv’uu’vv’ layers
– Expecting ~9 times K0S+L events
Masashi Kaneta, Tohoku Univ.
特定領域研究会於秋保緑水亭 2007/Nov/28

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