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( ). *. ( ) still a conventional name !. *. Report from. A. Passeri. Expression of Interest Physics goals Detector developments Collaboration setup. http://www.lnf.infn.it/lnfadmin/direzione/KLOE2-LoI.pdf. 72 physicists. 12 institutions. Expression of Interest.

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( )


( )still a conventional name !


Report from

A. Passeri

  • Expression of Interest

  • Physics goals

  • Detector developments

  • Collaboration setup

A.Passeri: KLOE-2 Report


72 physicists

12 institutions

A.Passeri: KLOE-2 Report

Expression of Interest

  • Vast physics program both at the f peak and in the range 1< s < 2.5 GeV

  • RequireʃLdt 50 fb-1in a 34 years running period at the f peak

  • (i.e. 5 x 1010 KSKL events and 7.5 x1010 K+K- events),

  • in order to reach significant sensitivities for the study of neutral kaon

  • interferometry, KS rare decays, lepton universality test and h, h’ program.

  • Require to run also at higher energies to accomplish the multihadronic cross

  • section measurement and the gg program. Energy scan highly recommended,

  • with average L∼1032cm-2s-1 .

  • Expect to start experimental program in 2011

  • Plan to use the KLOE detector with some important upgrades

A.Passeri: KLOE-2 Report

Physics goals at the f peak

Kaon physics: KS rare decays  pen, pmn, 3p0, p+p-p0,p0l+l- …

Study neutral kaon interference: search for CPT violation,

quantum decoherence, EPR phenomena, test Bell’s inequality.

Improve, where possible, all KLOE BR measurements  Vus

Search for LFV effects in Ke2 decays

h, h’ physics: extensive cPT tests, very sensitive to hadron structure,

light quark masses and couplings: h(h’)3p , h’hpp

Radiative decays: h(h’)gg, p+p-g, p+p-e+e- , hp0gg

C,CP violation: hpp, ggg, p0p0g,p0l+l-h’l+l-h

  • Light scalars: Investigate the nature of the established scalars f0(980), a0(980)

  • measure their s-quark couplings via f(f0+a0)gKKg

  • Search for the controversial lighter scalars s(600) and K*(800)

  • via gg process.

A.Passeri: KLOE-2 Report

Physics goals in the region 1≤s≤ 2.5 GeV

Hadronic cross section: Provide R measurement for am and aem determination.

Perform an accurate energy scan. Improve by a factor

of 10 the present BABAR exclusive cross section measurements.

Afford the only inclusive shad measurement since ’80s.

Vector meson spectroscopy:

study r, , f recurrencies and their place in hadron multiplets.

Understand the nature of r(1900) (glueball?).

gg physics: Study h’, f0, a0 production and their gg width (related to the

quark structure of the hadron).

The program is wide and spread over many topics.

All together they offer a rich experimental field.

In the following I will briefly discuss mainly the kaon part.

The rest will be addressed in C.Bini’s talk.

A.Passeri: KLOE-2 Report

G(K  pℓn(g)) 

|Vus f+K0p-(0) |2 I(lt) SEW(1 + dEM + dSU(2) )

The KLOE heritage: Vus

CKM matrix unitarity test can be refined by 1 order of magnitude.

|Vud|2 + |Vus|2 + |Vub|2~ |Vud|2 + |Vus|2  1 – D = 0.9997 ± 0.0013


Vud from superallowed Fermi transition

Vus dominated by KLOE measurements of K semileptonic decays:

Precision limited by hadronic corrections

KLOE does alsoextract |Vus| from (K())/(()) ratio.

Precision limited by the theoretical uncertainity on the fK/f evaluation.

Recent progress in lattice QCDseems to open the possibility of lowering the theoretical uncertainty to ∼0.1%

Considering the actual KLOE performances and assuming that

systematics will scale with statistics, a factor of 100 more statistics

is needed to match the theoretical precision, i.e. 40 fb-1

A.Passeri: KLOE-2 Report

Lepton universality test

In extended SUSY models large contributions

to Ke2 decay are expected from LFV terms:

First studies are going on in KLOE: need to fully exploit calorimeter for

e/m separation. A reasonable guess, based on present detector, is that

50 fb-1 would push relative error around 0.5%.

But : efficiency could improve dramatically with an increased calo granularity

and with a better inner tracking stage.

A.Passeri: KLOE-2 Report

CPT violation tests

Violation expected in QG models. No obvious scale predictions.

  • The f-factory environment provides a unique opportunity to test the

  • existence of such effect, in 3 different ways:

  • The comparison of KS and KL semileptonic decay charge asymmetries

  • Via the Bell-Steinberger relation

  • By studying the quantum interference between entangled kaon pairs

  • produced in f decays. This is also allow to perform tests of quantum

  • coherence, EPR paradox and Bell’s inequality.

A.Passeri: KLOE-2 Report

Cptv i k s semileptonic decay asymmetry
CPTV I : KS semileptonic decayasymmetry


G(KS,L  p-e+n) - G(KS,L  p+e-n)

AS,L =


G(KS,L  p-e+n) + G(KS,L  p+e-n)

CPT in


CPT in


S Q

and CPT


AS  AL  0



AS= 2(ReK ReK Re b/a Re d*/a)

AL = 2(Re K Re K Re b/a Re d*/a)

Present results:




KLOE 400pb-1

With a 50 fb-1 sample: s(AS)∼10-3

But:acceptance can be increased up to

a factor of 2 just by lowering the B field

A.Passeri: KLOE-2 Report

CPTV II : Bell-Steinberger relation

From unitarity conditions:

Im(d) ≠ 0 can be only due to CPTV, unitarity violation or exotic states.

After KLOE measurement of BR(KS3p0) : Im(d) = (1.2 ±3.0) 10-5

The next limiting inputs to B.S. are h+- and h00

A.Passeri: KLOE-2 Report







Dt=t1- t2


CPTV III :Quantum interference

  • interference pattern I(Dt) for different final

  • states f1,f2 give access to different parameters

  • a good vtx resolution is required: s(Dt)<tS

  •  quest for an improvement of inner tracking!

  • several QG models predict CPTV terms in the

  • interference time evolution


f1,f2 = p±l∓n

large Dt:

Semileptonic decays

give access to dK

small Dt:


A.Passeri: KLOE-2 Report

  • In the EHNS model the interference pattern contains 3 CPTV parameters:

  • a, b, g∼ o (MK2/MPlanck) ∼ 10-20 GeV KLOE measurements still worse than CPLEAR

KLOE2 figure of merit:

constant line is CPLEAR

VDET means svtx∼tS/4

  • in BMP model CPTV modifies the concept

  • of antiparticle and KSKL state deviates from

  • Bose statistics via a parameter :

Preliminary KLOE measurement is already at 10-4

level. KLOE2 can go up to 10-5

A.Passeri: KLOE-2 Report

Rare K introduced viaS decays

BR(KSpen)is still the limiting factor in the test of DS=DQ rule

by 3 error reduction on Re(x+)provided systematics scales with stat

BR(KSpmn) same as the above, but more difficult. Expected error at 0.4%.

BR(KSgg) test of cPT at o(p4). NA48 measurement 30% apart from calculations.

Current error is 2.7%. KLOE2 can go below 1%

BR(KSp+p-p0) another test of cPT, predictions around 10-7. KLOE2 expected

precision around 15%. Would benefit from B field reduction.

BR(KS3p0) CP and CPT test. Expected at 10-9, present limit at 10-7.

KLOE2 can aim to observe the signal.

BR(KSp0l+l-) very important to evaluate the CPV via mixing contribution to the

rare analogous decay of KL. Present NA48 measurement based on

7+6 events. With conservative efficiency estimate KLOE2 expects to

perform a measurement at the same level.

A.Passeri: KLOE-2 Report

R measurement and energy scan introduced via

Hadronic contribution to aem(MZ) is very important in the region 1<s<2.5 GeV

If not measuredat few % levelis going to be the limiting factor

for future precision calculation (linear collider physics).

B factories are already doing it !

Radiative return

with 2 fb-1 at 2.4 GeV

Energy scan

20 pb-1 per point


BABAR full stat


A.Passeri: KLOE-2 Report

The kloe detector
The KLOE detector introduced via



Lead/scintillating fiber

4880 PMTs

98% coverage of solid angle

4 m diameter × 3.75 m length

90% helium, 10% isobutane

12582/52140 sense/total wires

All-stereo geometry

E/E = 5.7% / E(GeV)

t = 54 ps / E(GeV)  50 ps

(finite bunch-length contribution subtracted)

p/p = 0.4 % (tracks with  > 45°)

= 150 m

z = 2 mm

solenoidal 0.5 T magnetic field

A.Passeri: KLOE-2 Report

The kloe concept

Calorimeter: introduced via

Drift Chamber:

Full angular coverage

Good momentum resolution

Large tracking volume

Exceptional timing capabilities

Minimization of materials

Large lever arm

The KLOE concept:

Excellent e/ separation based on t.o.f.

Good 0 reconstruction capabilities

Full kinematical reconstruction of events

The focus in KLOE design was mainly on efficiency for long-lived particles (K± ,KL), but the detector provides as well acceptable efficiency and resolution for prompt particles.

A.Passeri: KLOE-2 Report

KLOE detector “weaknesses” for DAFNE2 physics: introduced via

  • KLOE ( K LONG Experiment) was not fully optimized to detect low momentum tracks coming from IP (KS, h decay products)

  • Tracking starts at 25 cm from IP: both tracking and vertex efficiency affected

  • Calorimeter readout granularity does not prevent cluster merging and is not sufficient for a a shower-shape pid.

  • at f peak, gg physics impossible without small angle e± tagger

  • Physics and background rate could be an issue for DAQ and trigger

Proposed upgrades:

  • Lower B field from 0.5 T to 0.3 T (at least at f peak)

  • Add an inner tracker at 10< R < 25 cm

  • refine calorimeter readout granularity

  • Small Angle Tagger for gg events placed downstream

  • Trigger and DAQ upgrades

A.Passeri: KLOE-2 Report

5 KGauss introduced via

4 Kgauss

3 KGauss

Muon momentum in K± CM (MeV)


B field (KGauss)

B field: from 5  3 KGauss ?

  • Increase acceptance for low momentum tracks

  • coming from I.P.

  • Reduction of spiralizing tracks  less tails in

  • momentum resolution


Simulated Km2 events

Drawback:sp worsening for tracks at

higher pT (>150 MeV/c)

  • However:other effects, depending on the

  • channel, may partially compensate

  • According to simulation 40% B field

    reduction produce only a 15% sp increase

    in Km2 events

A.Passeri: KLOE-2 Report

Inner tracker: requirements introduced via

  • It must start at R≥ 20 tS , to avoid spoiling the KSKL interference path

  • To maximize acceptance it must extend up to q=30o

  • It must be able to provide independent tracking, i.e. must measure at least

  • 4 or 5 3D-spatial points.

  • It must be very light, not to spoil sP: a total material ∼1% X0 is acceptable

  • hit resolution: lS is only upper limit from physics… but for independent

  • tracking we must ensure that contribution to sP is better than M.S.

  •  shit∼200 mm is enough for 10 cm track length

  • it must sustain a very high rate: extrapolation from KLOE machine

  • background monitors yields a pessimistic figure od 3040 hits /plane/ms

  • easy: using straw tubes layers. Very light.

  • Electronics and mechanics “standard”.

  • challenging: cylindrical GEM. Expertise exists at LNF,

  • but detector shape is totally new.



A.Passeri: KLOE-2 Report

Courtesy of introduced via


Conversion &

Principle of operation of a GEM detector

The GEM (Gas Electron Multiplier) (F.Sauli, NIM A386 (1997) 531) is a thin (50mm) metal coated kapton foil, perforated by a high density of holes (70 mm diameter, pitch of 140 mm)  standard photo-lithographic technology.

By applying 400-500 V between the two copper sides, an electric field as high as ~100 kV/cm is produced into the holes which act as multiplication channels for electrons produced in the gas by a ionizing particle.

Gains up to 1000 can be easily reached with a single GEM foil. Higher gains (and/or safer working conditions) are usually obtained by cascading two or three GEM foils.

LHCb GEM configuration

A Triple-GEM detector is built by inserting three GEM foils between two planar electrodes, which act as the cathode and the anode.

A.Passeri: KLOE-2 Report

LNF Detector Development Group introduced via

F.Anulli, G.Bencivenni,

D.Domenici, G.Felici, F.Murtas

Cylindrical GEM development

  • The basic cylindrical structure can be realized with the straw-tube technology

  • The cylinder is obtained winding a parallelogram-shaped kapton foil. A helicoidal

    joint line (~3 mm wide) is left:

  • Two consecutive cylindrical electrodes have opposite

    “helicity” in order to reduce the overlap of joint lines

    to only one point (~3x3 mm2).

  • A detector layer is composed by five concentric cylindrical structures:

  • the cathode, the 3 GEM foils, the readout anode.

  • Anode and GEM3-down (where only electron fast signals are

  • present) are equipped with U-V strip readout for stereo view.

  • Strip pitch is 400 mm.

  • The cylindrical electrodes are glued at the ends on circular

  • frames, by which the detector can be hung to the beam

  • pipe, avoiding any internal support frame

First prototype for mechanical test

successfully produced

A.Passeri: KLOE-2 Report

GEM vs KLOE2 requirements : introduced via

  • Cylindrical GEM can be assembled in 5 detector layers at 10<R<25 cm

  • providing 3D spatial measurements for a total surface of 33000 cm2and

  • 27000 readout channels (for a 400 mm pitch).

  • Hit resolution around 170 mm.

  • Thickness grand total for 5 layers: between 0.92% and 1.57% X0

  • (depending on copper coat thickness).

  • Sustainable rate up to 50 MHz/cm2 (measured in planar GEM).

  • Time resolution ∼45 ns.

A.Passeri: KLOE-2 Report

introduced via


MC KS 30












Calorimeter readout granularity: why refine it ?

Avoid cluster splitting….

…and merging

…and on top of that..

Improve e/m/p

separation via

cluster shape


6 g events

After kinematic

fit c2 cut

Started a detailed calorimeter simulation based on FLUKA mc:

  • lead foils, including 5% Bi

  • glue Bicron BC-600ML, in all components

  • individual fibers:

  • polystirene core + PMMA cladding

A.Passeri: KLOE-2 Report

Standard KLOE calorimeter behaviour well reproduced for photons:



Energy and spatial

resolutions compared

to measured ones



Data resol

Eg (MeV)

Eg (MeV)

Cluster depth and rms

compared to

p+p- g events

centroid rms (cm)

centroid depth (cm)

Eg (MeV)

Eg (MeV)

A.Passeri: KLOE-2 Report

planes (depth) photons:

Columns ()

Granularity tests with 1000 events with two 200 MeV electrons



Digitized cells

KLOE granularity

Generated energy release




KLOE granularity x 16

KLOE granularity x 4

A.Passeri: KLOE-2 Report

planes (depth) photons:

Columns ()

Granularity tests with 1000 events with two 200 MeV muons

Digitized cells

KLOE granularity



Generated energy release




A.Passeri: KLOE-2 Report

Calorimeter granularity refinement: how to implement it ? photons:

  • Still a lot of work to do with simulation and comparison to KLOE data

  • Light readout could be performed with multi-anode PM tubes, like

  • Hamamatsu R7600-00M4 or 00M16, having very good risetime and

  • QE similar to present PMs.Sample of such devices already purchased,

  • to be tested very soon.

  • Light guides should be replaced with smaller ones: not an easy job !

  • Prototyping and testing is mandatory

  • Granularity could be refined only on first 1 or 2 planes, and eventually only

  • in the barrel region.

  • FEE should be redesigned for the new cells, while old cells FEE boards can

  • be used as spares for the remaining ones.

A.Passeri: KLOE-2 Report

Trigger considerations photons:

Simple rate scaling

shows that KLOE2

Must work well above

10 KHz total rate,

depending on machine bckg


  •  events300 Hz2500 Hz

  • Good Bhabhas600 Hz5000 Hz

  • Residual cosmics600 Hz600 Hz

  • Machine backgr.500 Hz ?

  • If machine bckg does not increase dramatically, present minimum bias

  • trigger strategy (2 hw lvls + 1 sw) can be mantained, with Bhabha prescaling ON.

  • The 3rd level filter must become more selective, to minimize the fraction of

  • non-interesting events on tape.

  • Most of the present trigger custom boards (11 diferent types) need to be

  • designed, for lack of spares and components obsolescence

  • DC trigger need to be reconsidered: actual thresholds are not easily under

  • control, and may change trigger conditions unexpectedly.

  • A gg physics trigger must be included

  • At high energy multiplicity will increase: trigger should be even more efficient.

  • However threshold tuning will be necessary.

A.Passeri: KLOE-2 Report

DAQ at KLOE2 photons:

  • KLOE DAQ was designed to sustain 50 Mbyte/s and was tested up to

  • 80 Mbyte/s , divided between 10 similar acquisition chains.

  • Its architecture can be kept, provided we overcome 3 bottlenecks :

  • VME block transfer from 2nd lvl concentrator to CPU, limited at 20 Mbyte/s

  •  VME64x protocol, together with the new 2eSST block transfer (Double-edge

  • Source Syncronous Block Transfer) can transmit up to 320 Mbyte/s !

  • FDDI data transfer from 2nd lvl CPUs to onlinefarm, limited at 12.5 Mbyte/s

  •  can be replaced by Gigabit Ethernet

  • 2nd lvl CPUs (old DEC) data framing, limited around 8 Mbyte/s

  • Motorola MVME6100 implements both VME64 and Gigabit Ethernet

A tester board has been realized to test the

full environment.

MVME6100 running Linux with a custom

vme driver and the KLOE online sw.

Measured sustained rate is 180 Mbyte/s


A.Passeri: KLOE-2 Report

Setup of the collaboration photons:

For the moment : 72 physicists in 12 institutions

Out of which: 44 are italians 4 are italians

41 are also in KLOE 7 are also in KLOE

Doors are open to newcomers

who share the same physics program

  • By end of june a KLOE2 full meeting is planned to:

    • start giving the collaboration a governing structure

    • define together the next milestones and start sharing working items

A.Passeri: KLOE-2 Report

Conclusions photons:

A sizeable group of experimental physicists has expresses interest in

a wide physics program to be performed at the next Frascati e+e-

collider, both at the f peak and at higher energy

We plan to use the KLOE detector with some important upgrades,

for which we have already started developments.

A.Passeri: KLOE-2 Report

Spare Slides photons:

A.Passeri: KLOE-2 Report

V us from kloe results br s and t l

Slopes photons:

l+ = 0.02534(30)

l+ = 0.00128(3)

(Pole model: KLOE,

KTeV, and NA48 ave.)

l0 = 0.01587(95)

(KTeV and Istra+ ave.)

From unitarity

  • f+(0)=0.961(8)

  • Leutwyler and Roos Z.

  • [Phys. C25, 91, 1984]

  • Vud=0.97377(27)

  • Marciano and Sirlin

  • [Phys.Rev.Lett.96 032002,2006]

Vus×f+(0) = 0.2187(22)

Vus from KLOE results (BR’s and tL)

c2/dof = 1.9/4

A.Passeri: KLOE-2 Report

V us and unitarity

V photons:us f+(0)

plot: F.Mescia courtesy

From unitarity

  • f+(0)=0.961(8)

  • Leutwyler and Roos Z.

  • [Phys. C25, 91, 1984]

  • Vud=0.97377(27)

  • Marciano and Sirlin

  • [Phys.Rev.Lett.96 032002,2006]

Vus×f+(0) = 0.2187(22)

Vus and Unitarity

  • tL = 50.99(20) ns,

  • average KLOE-PDG

  • Including all new measurements

  • for semileptonic kaon decays

  • (KTeV, NA48, E865, and KLOE)

<Vus×f+(0)>WORLD AV. = 0.2164(4)

A.Passeri: KLOE-2 Report

The v us v ud plane
The V photons:us- Vud plane


Vus = 0.2254  0.0020

Kl3 KLOE, using f+(0)=0.961(8)

Vud = 0.97377  0.00027

Marciano and Sirlin

Phys.Rev.Lett.96 032002,2006

Vus/Vud = 0.2294  0.0026


(K())/(())  |Vus|2/|Vud|2fK2/f2


Fit results, P(c2) = 0.66:

Vus = 0.2246  0.0016

Vud = 0.97377  0.00027

Fit result assuming unitarity, P(c2) = 0.23:

Vus = 0.2264  0.0009

A.Passeri: KLOE-2 Report

Ke2 momentum distribution
Ke2 Momentum distribution photons:

Red = MC

blu = ke2

black data

  • We use as starting point a sample of 80000 K+e2 corresponding to 2fb statistic. (IB+SD)

  • MC 2005 was used with the new charged kaon noise inserted

  • The K+ decay must be reconstructed with vertex in FV

  • The electron momentun ranges in 200-300 MeV/c region. Same as the muons from K2

Lab momentum



A.Passeri: KLOE-2 Report

Multiple scattering vs thickness





Silicon 1.5mm


Silicon 1.5mm


silicon 1mm

silicon 1mm





P (MeV/c)

P (MeV/c)

Multiple scattering vs thickness

Comparison between MS induced by 2 reference value of silicon thickness (1mm and 1.5 mm) wrt a KLOE-like:≈ 700m of carbon fiber.

A thickness larger than 1mm of silicon equivalent (≈ 1% of X0) can be a limiting factor for the momentum mesurement of low momentum particle coming from IP .

Problem can also be given by the conversion of photons from machine

A.Passeri: KLOE-2 Report

R photons:













Level 2

Level 1

16 DAQ FEE boards





AUX bus






Trigger lines


VME bus

VME bus

Vic bus



















Trigger lines

DAQ Chain

AUX bus

A.Passeri: KLOE-2 Report

In KLOE the link and the switch between fee and farm is based on


A.Passeri: KLOE-2 Report