The last oscillation: mu2e at Fermilab
Vadim Rusu Fermilab Flavor oscillations
Maybe the most important feature of the SM
why are 3 families anyway? Quarks change flavor (CKM), neutral leptons change flavor (MNS) Do charged leptons oscillate? (CLFV)
answer:
BNL Seminar Vadim Rusu - The last oscillation: mu2e 2 Flavor oscillations
Maybe the most important feature of the SM
why are 3 families anyway? Quarks change flavor (CKM), neutral leptons change flavor (MNS) Do charged leptons oscillate? (CLFV) answer: YES
BNL Seminar Vadim Rusu - The last oscillation: mu2e 2 ✴ anomaly in muon g-2 (?)
Hagiwara et al: hep-ph/0611102
Neutrinos have mass
+ + µ µ e → e γ W˜ µ e ˜µ ˜e
6
BNL Seminar Vadim Rusu - The last oscillation: mu2e 3 ✴ anomaly in muon g-2 (?)
Hagiwara et al: hep-ph/0611102
Neutrinos have mass
+ + µ µ e → e γ W˜ µ e ˜µ ˜e
2 2 3 m1i 54 6 BR(µ e⇥) = U ⇥ U < 10 32⌅ µi ei M 2 i=2,3 W ⇥
BNL Seminar Vadim Rusu - The last oscillation: mu2e 3 ✴ anomaly in muon g-2 (?)
Hagiwara et al: hep-ph/0611102
Neutrinos have mass
+ + µ µ e → e γ W˜ µ e ˜µ ˜e
2 2 3 m1i 54 6 BR(µ e⇥) = U ⇥ U < 10 32⌅ µi ei M 2 i=2,3 W ⇥ - not going to measure this one soon
BNL Seminar Vadim Rusu - The last oscillation: mu2e 3 History
CLFV: not a new idea In fact, almost everyone looked for this
1 10-1
10-3
10-5
10-7
10-9
10-11
10-13
10-15
10-17
10-19 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030
BNL Seminar Vadim Rusu - The last oscillation: mu2e 4 History
CLFV: not a new idea In fact, almost everyone looked for this
1 μ discovered in 1936 10-1
10-3
10-5
10-7
10-9
10-11
10-13
10-15
10-17
10-19 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030
BNL Seminar Vadim Rusu - The last oscillation: mu2e 4 History
CLFV: not a new idea In fact, almost everyone looked for this
1 μ discovered in 1936 10-1
10-3 Feinberg 1958 loop calculation μ→eγ ~ 10-4-10-5 10-5
10-7
10-9
10-11
10-13
10-15
10-17
10-19 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030
BNL Seminar Vadim Rusu - The last oscillation: mu2e 4 History
CLFV: not a new idea In fact, almost everyone looked for this
1 μ discovered in 1936 10-1
10-3 Feinberg 1958 loop calculation μ→eγ ~ 10-4-10-5 10-5
-7 Non observation of μ→eγ 10 (implies two neutrinos) 10-9
10-11
10-13
10-15
10-17
10-19 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030
BNL Seminar Vadim Rusu - The last oscillation: mu2e 4 History
CLFV: not a new idea In fact, almost everyone looked for this
1 μ discovered in 1936 10-1
10-3 Feinberg 1958 loop calculation μ→eγ ~ 10-4-10-5 10-5
-7 Non observation of μ→eγ 10 (implies two neutrinos) 10-9 Best limit so far 10-11
10-13
10-15
10-17
10-19 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030
BNL Seminar Vadim Rusu - The last oscillation: mu2e 4 History
CLFV: not a new idea In fact, almost everyone looked for this
1 μ discovered in 1936 10-1
10-3 Feinberg 1958 loop calculation μ→eγ ~ 10-4-10-5 10-5
-7 Non observation of μ→eγ 10 (implies two neutrinos) 10-9 Best limit so far 10-11
-13 mu2e10 intends to improve 10-15by 10000 and then 100 more w/ Project X 10-17
10-19 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030
BNL Seminar Vadim Rusu - The last oscillation: mu2e 4 New physics
Supersymmetry Compositeness Leptoquark MLQ = rate ~ 10-15 Λ ~ 3000 TeV 1/2 2 c 3000 (λμdλed) TeV/c ~χ 0 i - µ- e- µ d ~~ - lj lj - µ e L LQ
qqq q d e-
Heavy Neutrinos Second Higgs Doublet Heavy Z’ Anomal. Z Coupling 2 -13 g(H ) ~ 10-4g(H ) |UμNUeN| ~ 8x10 μe μμ 2 MZ’ = 3000 TeV/c - N - e - µ e µ- e- H t W µ- - e tt γ,Z,Z’
qqqqq q also see Flavour physics of leptons and dipole moments, arXiv:0801.1826 and Marciano, Mori, and Roney, Ann. Rev. Nucl. Sci. 58, doi:10.1146/annurev.nucl.58.110707.171126
BNL Seminar Vadim Rusu - The last oscillation: mu2e 5 Model independent
Andre deGouvea (TeV) Λ B(μ→ e conv in 27Al)=10-17
4 10
κ << 1 κ >> 1 Mu2e B(μ → e conv in 27Al)=10-16 magnetic moment type four-fermion interaction operator MEG Upgrade µN → eN rate many µ → eγ rate ~300X MEG GOAL B(μ → eγ)=10-13 orders of magnitude µN → eN rate greater than µ → eγ rate 3 10 MEGMEGA 2011
SINDRUM II scale mass higher
EXCLUDED (90% CL)
-2 -1 2 10 10 1 10 10 loop-dominated κ contact-dominated
BNL Seminar Vadim Rusu - The last oscillation: mu2e 6 Muon to electron conversion
µ+ → e+γ
Time scale for entire process ~μs
μ
BNL Seminar Vadim Rusu - The last oscillation: mu2e 7 Muon to electron conversion
µ+ → e+γ
Time scale for entire process ~μs
μ
muons captured on target formation of atomic muon
BNL Seminar Vadim Rusu - The last oscillation: mu2e 7
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BNL Seminar Vadim Rusu - The last oscillation: mu2e γ Massiv
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part
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e
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exp
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γ CLFV erimen
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t new
y m the
- trapp
e
e
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neutrinos
e discussed pro
+ en ersion
to
the
nature
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that ounds
v
+
existence
including
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pla
exp
48 til
e
the
→
will
deep →
γ
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→
to
e
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b
the
of giv - trapp kly
e
violating neutrinos
concurren e discussed
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the
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hes
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or
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masses.
v
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ely
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imp
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transitions
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],
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for
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reac × of
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while µ
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transitions
1 stand
ev
k
distinct
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titanium),
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13
,
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lepton-fla
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orts
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in
rule
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e
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matter
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reac ×
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of
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−
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titanium),
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and
[21
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ph
µ
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4 immediate
that
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µ,
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its
=
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times of
than
e
e
ab ones,
is ].
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connection
een con
in
results
is
the its e, v
nature
erts subsection.
3 of
either
lepton
v
Muon to electron conversionα 12
of
CLFV
. t. in is
new
b
m
it
ratios v
electromagnetic
→
new
rare
−
driv e
ultimately
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, 4
that
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that
ha
its
=
times
in
than
eral
less
lifetime: k
e
e
es
cesses, cesses
than
+ + uons
con
µ
10
α
is
the
its v
erts subsection.
of
either
→ lepton
→
con α γ
e 12
of
CLFV
µ e γ the PSI, in factors,
ts
next
ratios v
×
m
U →
and
uons
rare
yp −
e
e
X Rays sev significan
b
,
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that hing
ha
t
pro
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0
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less
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of
at
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→
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than
while
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m
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of
at branc
process ~μs .
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→
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and h eren t
o
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whic
data
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rate
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harged tly
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e subsection, ff
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c
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m
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than rapp
nature the as ab while exp
uon
most
curren
the
of
sup di
v
erimen in branc hannels,
establishing sources,
T
and
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scale, e uon o
these
c whic
op data
el, m t
rate with
larger
harged
to
rare
subsection,
ff
to to
mass b
ely
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Among
next m erior
far
osal
rapp nature γ the the as ab exp
Pr
curren
of di lev
taking
eV hannels, one
atoms,
T
to
+
scale,
e
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c constrained
op
el, t with
standard ratios
larger capture
T as
discussed e
rare
sup
mass b
the
“feel”
ely
y
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eigenstates,
tribution on next
m erior far matrix.
γ the
e is tly ratios Pr
three
CLFV
lev Curren
taking
eV
small one
→
atoms,
ysics.
in
b an out orbital.
to
+
constrained
the
t
future standard ratios
the
capture
the
T Mu2e
as con discussed e
Negativ
role
hing promising
sup
muons captured on target the
“feel”
y
s
eigenstates, uonic tribution
on e
all
uclear-captured matrix.
ph
cess +
e is tly
ratios
three in
1
mass v CLFV
Curren
n
small µ hing
of gold
to
→
formation of atomic muon m
ysics.
in b an out orbital.
o
will
the
eren t
tal of
future
the
the
curren
Mu2e
CLFV,
con
mixing
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a
role
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hing promising
pro
turns
s
ff
uclei. immediately (~ps) falls to 1s (X rays) → uonic detail
e
all confidence
uclear-captured
ed
in
ph
cess tense
+
ab
el,
new
branc ],
in
1
n
mass v
most
normalization m
n e
of
µ hing of gold to m di
o in
eral will
v
eren
tal of
curren
branc CLFV,
mixing
neutrino
e
a
en lev
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the Bohr radius is 20fm → muon sees o pro
[24
turns
in
ff uclei. detail
confidence
ed
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tense
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e ab
el,
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ysics.
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nucleus (~4fm) n the most
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e
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ab
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ph
o
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examples
v in + or
to
fundamen
b
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the
ysics. the 90% are
normalized the
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the
neutrino
three
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ab
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ersion
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con
of
ph
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v
examples
v at + or
to
fundamen
Ti
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is part
the
the
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e
.
ts the
−
confidence
exploration
at
i
7 ersion
BNL Seminar Vadim Rusu - The last oscillation: mu2e γ Massiv
1.1:
con
e
con
of
ysics
ν e v in
at
Ti
+
part
Among Concrete
e
.
ts
ph
→ confidence
γ
1.1: con
ysics
e in elemen
µ
Concrete Figure
ph →
elemen
µ Figure
the
field
form
e
in
the
the
the
γ field
t
more
where
ery is e
form
v of
to
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in and prob
in
→ the n
the
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uclei.
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and prob
erimen
listed
in t new
y m
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e
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pro of
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v
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including
µ
ed
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exp
48
e
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deep
γ CLFV erimen
listed
→
t new
y m the
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e
e
pro
neutrinos
e discussed pro
+ en ersion
to
the
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that ounds
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including
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pla
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will
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→
to
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of giv - trapp kly
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h are
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3 of
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that
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10
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is
the
its v
erts subsection.
of
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con α γ
e 12
of
CLFV
µ e γ the PSI, in factors,
ts
next
ratios v
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m
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and
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eral
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uons
of
at
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long
c
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α ersymmetric (
→
h t
→
con
γ
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to
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uon the PSI,
factors,
the
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significan
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than
while
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most µ
the
m
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v erimen
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process ~μs .
long
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(
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and h eren t
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these
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data
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rate
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larger
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taking
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atoms,
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standard ratios
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discussed e
rare
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mass b
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“feel”
ely
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eigenstates,
tribution on next
m erior far matrix.
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lev Curren
taking
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small one
→
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in
b an out orbital.
to
+
constrained
the
t
future standard ratios
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capture
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T Mu2e
as con discussed e
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role
hing promising
sup
muons captured on target the
“feel”
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s
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on e
all
uclear-captured matrix.
ph
cess +
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ratios
three in
1
mass v CLFV
Curren
n
small µ hing
of gold
to
→
formation of atomic muon m
ysics.
in b an out orbital.
o
will
the
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tal of
future
the
the
curren
Mu2e
CLFV,
con
mixing
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a
role
ending uon’s
hing promising
pro
turns
s
ff
uclei. immediately (~ps) falls to 1s (X rays) → uonic detail
e
all confidence
uclear-captured
ed
in
ph
cess tense
+
ab
el,
new
branc ],
in
1
n
mass v
most
normalization m
n e
of
µ hing of gold to m di
o in
eral will
v
eren
tal of
curren
branc CLFV,
mixing
neutrino
e
a
en lev
Dep ending uon’s
the Bohr radius is 20fm → muon sees o pro
[24
turns
in
ff uclei. detail
confidence
ed
in
tense
b
e ab
el,
new
branc ],
ysics.
90%
nucleus (~4fm) n the most
sev
m
e
lepton ev of the
neutrino
three with
di
ab
in eral
observ v
ersion
branc
neutrino
e
en lev Dep
conversion electron ~105MeV ph
o
[24
examples
v in + or
to
fundamen
b
e
e
is
the
ysics. the 90% are
normalized
the
sev
lepton ev
the
correct for recoil and BE neutrino three
the with
ab
−
observ exploration at i ersion
Massiv
ersion
e
con
of
ph
ν
v
examples
v at + or
to
fundamen
Ti
+ e
is part
the
the
Among are normalized
e
.
ts the
−
confidence
exploration
at
i
7 ersion
BNL Seminar Vadim Rusu - The last oscillation: mu2e γ Massiv
1.1:
con
e
con
of
ysics
ν e v in
at
Ti
+
part
Among Concrete
e
.
ts
ph
→ confidence
γ
1.1: con
ysics
e in elemen
µ
Concrete Figure
ph →
elemen
µ Figure But what really happens...
Muon decay in orbit Nuclear muon capture
BNL Seminar Vadim Rusu - The last oscillation: mu2e 8 Muon decay
μ decay in orbit spectrum 27Al
2 2 mµ + me Ee(max) = 52.8 MeV 2mµ
Michel spectrum from free decay
BNL Seminar Vadim Rusu - The last oscillation: mu2e 9 Muon decay
μ decay in orbit spectrum 27Al
BNL Seminar Vadim Rusu - The last oscillation: mu2e 9 Nuclear muon capture
μ+A(Z,N)→ νμ+A(Z’,N’)+an+bp+cγ For Al: a≈1.5, b≈0.1, c≈2 protons protons are easy to reconstruct but hitting the 20-30x more ionizing → high charge spectrometer spurious hits neutrons are not a direct tracking problem but high fluences affect detectors can knock out electrons, photons γ’s can convert into e+e-
Rates in the tracker are dominated by neutron induced processes
Highest rate in the live window < 300kHz
BNL Seminar Vadim Rusu - The last oscillation: mu2e 10 ...and other processes
Muon decay in orbit Nuclear muon capture and others: radiative pion captures beam electrons, antiprotons in flight μ and π decays more onlater! all those cosmic rays
BNL Seminar Vadim Rusu - The last oscillation: mu2e 11 Current state ofSINDR the UMart II @ PSI
W. Bertl et al., Eur. Phys. J. C 47, 337–346 (2006) SINDRUMII at PSI Class 1 events: prompt forward removed e- measurement 3 10 e+ measurement Final Run on Au at PSI MIO simulation 10 2 µe simulation -13 Rμe<7×10 10 Final result on mu - e 1 event past the end of the conversion on Gold spectrum 1 target is being prepared 80 90 100 events / channel radiative pions, CR? Class 2 events: prompt forward for publication
PSI has a DC beam - more on 10 this later -13 1 < 7 x 10 90%CL
80 90 100 momentum (MeV/c)
BNL Seminar Vadim Rusu - The last oscillation: mu2e 12 A textbook mu2e experiment
BNL Seminar Vadim Rusu - The last oscillation: mu2e 13 A textbook mu2e experiment
BNL Seminar Vadim Rusu - The last oscillation: mu2e 14 A textbook mu2e experiment
Lots of muons 50000000000/s ×1000 compared to last Total: 5×1019 → 100× less than the number of grains of sand on Earth beaches
BNL Seminar Vadim Rusu - The last oscillation: mu2e 14 A textbook mu2e experiment
Lots of muons 50000000000/s ×1000 compared to last Total: 5×1019 → 100× less than the number of grains of sand on Earth beaches No beam contamination <10-10 out-of-pulse/in-pulse 10-3 -10-4 typical
BNL Seminar Vadim Rusu - The last oscillation: mu2e 14 A textbook mu2e experimentMu2e Proposal
Lots of muons 50000000000/s ×1000 compared to last Figure 1.4: µ e conversion rate for different nuclei, normalized to that for µ e → → Total: 5×1019 → 100× less than the numberconversion in aluminum. The different curves represent the contribution of different types of grains of sand on Earth beachesof higher dimensional operators. See Ref. [27] for details. No beam contamination <10-10 out-of-pulse/in-pulse the rate for µ e-conversion in different nuclei, since different nuclei are sensitive to new physics→in distinct ways, as depicted in Fig. 1.4 [27]. This flexibility is not 10-3 -10-4 typical shared by µ eγ (where one can only hope to measure, in principle, the final state Target with high Z and long lifetimephoton or electron→ polarizations [28]). In the case of a positive signal in µ eee, some detailed information regarding the underlying physics can also be obtained→ by analyzing in detail the kinematics of the three final state leptons. See, for example [29–31].
BNL Seminar Vadim Rusu - The last oscillation: mu2e 14 1.2.2 CLFV and new physics at the TeV scale By the end of 2009, we expect the LHC experiments to start accumulating data that will reveal the mechanism of electroweak symmetry breaking and explore the physics of the TeV scale. Several theoretically motivated scenarios predict the existence of new degrees of freedom with masses at or below 1 TeV and, if this is the case, one expects some of these new states to be discovered at the LHC. New degrees of freedom at the TeV scale are expected to mediate CLFV processes. Expectations are model-dependent, but detailed computations in specific models lead to CLFV rates very close to current experimental bounds, as will be discussed in more detail shortly. We first conservatively assume that the new physics will predominantly induce flavor-violating magnetic-moment type effective interactions at the one-loop level. A concrete example is depicted in Fig. 1.5. In this case, CLFV is given by Eq. (1.5) (potentially augmented by similar oper-
8 A textbook mu2e experiment
Lots of muons 50000000000/s ×1000 compared to last Total: 5×1019 → 100× less than the number of grains of sand on Earth beaches No beam contamination <10-10 out-of-pulse/in-pulse 10-3 -10-4 typical Target with high Z and long lifetime Perfect resolution spectrometer in vacuum with zero mass
BNL Seminar Vadim Rusu - The last oscillation: mu2e 14 A textbook mu2e experiment
Lots of muons 50000000000/s Too hard!!!!! ×1000 compared to last Total: 5×1019 → 100× less than the number of grains of sand on Earth beaches No beam contaminationmaybe is time to look at etomu? <10-10 out-of-pulse/in-pulse 10-3 -10-4 typical Target with high Z and long lifetime Perfect resolution spectrometer in vacuum with zero mass
BNL Seminar Vadim Rusu - The last oscillation: mu2e 14 mu2e collaboration
Boston University Brookhaven National Laboratory University of California, Berkeley University of California, Irvine California Institute of Technology City University of New York Duke University Fermilab University of Houston University of Illinois, Urbana-Champaign University of Massachusetts, Amherst Lawrence Berkeley National Laboratory Northern Illinois University Northwestern University Istituto G. Marconi Roma Institute for Nuclear Pacific Northwest National Laboratory Research, Moscow, Russia Rice University Laboratori Nazionale di Frascati JINR, Dubna, Russia University of Virginia Università di Pisa, Pisa University of Washington, Seattle INFN Lecce and Università del Salento Gruppo Collegato di Udine ~130 collaborators
BNL Seminar Vadim Rusu - The last oscillation: mu2e 15 Fermilab complex
Booster: 4×1012 p/batch every 1/15s Nova: 12 stacked in the Recycler and then to MI MI cycle 1.33s 8 batches available 2 used by mu2e Recycler RF manipulation into 4 bunches ~200ns each Transfer to Debuncher Debuncher period 1.7μs Resonant extraction from Debuncher → beam to muon production target
6×1012 p/s delivered to muon production
3.1×107 protons/bunch
BNL Seminar Vadim Rusu - The last oscillation: mu2e 16 Fermilab muon campus
Reuse as much as possible the current collider g-2 complex Mu2e
Small changes to the existing antiproton rings
Allow mu2e and g-2 this decade (8GeV muon program)
No interference with the 120GeV neutrino program (Noνa)
BNL Seminar Vadim Rusu - The last oscillation: mu2e 17 Experiment
π from p in PS - π→μν μ’s spiral down in S shape solenoid (TS) μ’s end on the conversion target in DS
Production Solenoid Detector Solenoid
Transport Solenoid 10-4 Torr vacuum throughout
BNL Seminar Vadim Rusu - The last oscillation: mu2e 18 Production
Protons leave through 4.6T Proton Target thin window (extinction (W rod 160 × 3 mm) measurement after) Target Shielding 2.5T Pions (captured in gradient B) Protons enter here (opposite to outgoing µ’s)
4m x 0.3m
BNL Seminar Vadim Rusu - The last oscillation: mu2e 19 Transport
2.0T Curved solenoid eliminates line of sight No neutrals transport Sign selection S shape solenoid + collimator
2.5T 13.1m x 0.25m
BNL Seminar Vadim Rusu - The last oscillation: mu2e 20 Detection
Calorimeter Tracker ~1024 3.5 x 3.5 x 12 cm Transverse geometry PbWO4 or LYSO 21600 straws 2% resolution 18 stations Magnetic mirror increases 1.0T acceptance beam dump 2.0T
shielding and cosmic veto
p absorber
10 m × 0.95 m Al foils
Tracker hits → Radius → p (=qBR) Calorimeter charge → Energy
BNL Seminar Vadim Rusu - The last oscillation: mu2e 21 mu2e calorimeter
Vane (baseline) electron tracks spiral into flat faces neutrons from stopping target hit edge Disk (new idea) facing neutrons, so potentially more accidental activity worsening resolution charge-symmetric!
BNL Seminar Vadim Rusu - The last oscillation: mu2e 22 mu2e calorimeter
Trigger the detector
Confirm the track
Separate measurement
BNL Seminar Vadim Rusu - The last oscillation: mu2e 23 mu2e Tracker
Tracker 21600 straws in vacuum • ~39 hits/track • <0.25 X0 for a typical track Electronics at straw end All support at large radius
Self supporting panels assembled into planes Planes assembled into stations Rotating 60º for improved stereo
BNL Seminar Vadim Rusu - The last oscillation: mu2e 24 mu2e Tracker
Tracker 21600 straws in vacuum • ~39 hits/track • <0.25 X0 for a typical track Electronics at straw end All support at large radius
Self supporting panels assembled into planes Planes assembled into stations Rotating 60º for improved stereo Tracking at high radius only ensures operability (beam flash!)
BNL Seminar Vadim Rusu - The last oscillation: mu2e 24 mu2e straw
15 microns Mylar
2x6.25μm Mylar spiral wound
500Å Al
200Å Au on inner surface
5mm diameter straws
25 μm W sense wire (Au covered)
334-1174 mm in length
ArCO2 (80/20) at HV<1500
BNL Seminar Vadim Rusu - The last oscillation: mu2e 25 A mu2e event
Single proton pulse
particle hits in 500-1695ns window
good timing helps (±50 ns around C.E.)
Problem: find the red track Pattern recognition very hard
BNL Seminar Vadim Rusu - The last oscillation: mu2e 26 Measuring the 3’rd coordinate
z along the straw obtained at high precision after the fit (stereo) Crucial for pattern recognition Time division (read both ends of the straw)
BNL Seminar Vadim Rusu - The last oscillation: mu2e 27 Time Division
Achieved 3.5cm with mu2e straws
Limited by noise → could improve (performance already to spec)
BNL Seminar Vadim Rusu - The last oscillation: mu2e 28 Electronics
ASIC%(1) Discrete%(1) FPGA
Preamp
TDC
Straw
TDC DAQ PCB'transmission'line
∫ Readout'Controller & & Output'Control'&'Buffer ∑ '
ADC Preamp
BNL Seminar Vadim Rusu - The last oscillation: mu2e 29 Tracker performance
Studied with full G4 simulations Realistic background rates included
Crystal ball function for intrinsic tracker resolution Core σ=115keV/c Tail σ=176keV/c Signal simulation FWHM~1MeV/c ~2/3 resolution = straggling before tracker Al foils Proton absorber
BNL Seminar Vadim Rusu - The last oscillation: mu2e 30 DIO (why we need to know resolution)
~100k events with P>80MeV well understood calculations (very important) Czarnecki, Tormo, Marciano 2011 (Phys. Rev. D 84, 013006 (2011))
Nbkg = Theory ⊕ Resolution add effect of changing reso here Special runs varying target foils, field, location of targets Monoenergetic line from π+→ eν ~70MeV e+ New ideas being looked at electrons from cosmic muons
BNL Seminar Vadim Rusu - The last oscillation: mu2e 31 Cosmic muons (why a cosmic veto)
scintillating counters read by SiPMs The easiest way to make a 105MeV electron (silicon photomultiplier) Hermetic around the detector 99.99% efficient <5ns time resolution resist neutron flux
In some regions neutron flux too high
Solution: cathode strip chambers → neutron blind
BNL Seminar Vadim Rusu - The last oscillation: mu2e 32 Pions (why track positrons)
((abs([2]-x))**[0])*exp(-(abs([2]-[5]*x))/[1])*([3]+[4]*x)
Fit
Entries 17475 1200
Entries Mean 114.9
RMS 12.27
Radiative Pion Captures 2 χ / ndf 236.8 / 25 1000 p0 ± - 1.909 0.029 π N → γN’ γ momentum can p1 9.855 ± 0.203 p2 135.7 ± 0.1 - + extend to mπ peak at 800 γN → e e N p3 -18.21 ± 3.66 ~110MeV p4 0.6085 ± 0.0417 p5 0.9408 ± 0.0058 Fortunately, τπ <<τμ 600
waiting helps 400 e+ ≃ e- 200 measure e+ (use P 0 sidebands for 40 60 80 100 120 140 extrapolation) Energy (MeV)
BNL Seminar Vadim Rusu - The last oscillation: mu2e 33 Late arriving particles (why 10-10 in between beam)
Beam electrons, μ and π decays in flight
potential backgrounds
Extinction between pulses < 10-10
e = Np out-of-pulse/Np in- pulse
requirement based on simulations
AC dipole + collimators
We also need to measure this
Fast response measurement upstream
Integrate (~1hours) for a statistical significant number of secondary tracks
BNL Seminar Vadim Rusu - The last oscillation: mu2e 34 Signal and Backgrounds
3 years of 1.2 × 1020 p/ year (8kW beam power) DIO Signal
-15 For Rμe=10 ~40 events
BNL Seminar Vadim Rusu - The last oscillation: mu2e 35 A look (far) ahead
intense proton source that provides beam to MI (neutrino program) mu2e signal? 8 GeV physics program Rich muon physics YES NO mu2e μ → e γ Change target Repeat - higher sensitivity muonium-antimuonium oscillations Higher rates, need to reduce backgrounds Prompt backgrounds others redesign muon beamline, detector, cosmic redesign muon beamline and detector veto
BNL Seminar Vadim Rusu - The last oscillation: mu2e 36 mu2e schedule
Solenoids drive the schedule
Start detector construction in 2 years
Expect to start cosmics run in 2019-2020
BNL Seminar Vadim Rusu - The last oscillation: mu2e 37 Conclusions
mu2e is a discovery experiment 10000× more sensitive than last In the light of first LHC data it is even more important now to look for effects of new physics from scales >>LHC mu2e is capitalizing on a large existing infrastructure at Fermilab A very challenging experiment (where would be the fun if not) with very advanced understanding of the problems and how to address them
http://mu2e.fnal.gov
BNL Seminar Vadim Rusu - The last oscillation: mu2e 38