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1 B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNFINFN) for the KLONE Group XXXIII LNF Scientific Committee Open session 27 November 2006

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Page 1: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

1B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Neutron detection efficiency of the KLOE calorimeter

B.Sciascia(LNFINFN)

for the KLONE Group

XXXIII LNF Scientific CommitteeOpen session

27 November 2006

Page 2: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

2B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

OutlineThe KLONE (KLOe Neutron Efficiency) group measured the neutron detection efficiency of a KLOE calorimeter prototype, at The Svedberg Laboratory (TSL), Uppsala.

• Reasons behind the formation of the KLONE group.

• Characteristic of the neutron source at TSL.• Experimental setup.

• Measurements: Method Neutron detection efficiency for a 5 cm thick scintillator. Calorimeter neutron detection efficiency, preliminary results. Neutron energy spectrum from Time of Flight, preliminary results.

• Monte Carlo: Some comparisons between data and “fast” Monte Carlo. Detailed beam line and calorimeter simulation. Physical processes behind the test beam results.

Page 3: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

3B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

The reasons behind KLONE • Preliminary measurement with KLOE data and MC (neutron are produced by K interactions with the beam pipe and inner DC walls) showed an efficiency of 40%, larger than the expected 10% if only the amount of scintillator is taken into account. (B. Sciascia, www.lnf.infn.it/kloe/kloe2/memoneueff.pdf)Thumb rule: efficiency scales with scintillator thickness (1%/cm).

• Several works in literature mention an enhancement of neutron detection efficiency for fast neutron in presence of high Z materials, particularly lead (e.g. see M.Pelliccioni et al., NIMA 297 (1990) 250-257).

• KLOE calorimeter has very good time resolution, good energy resolution, and high efficiency for photons. With high neutron detection efficiency, could be also the first of a new kind of neutron detectors.

• High neutron detection efficiency is relevant for the future experiments at LNF: AMADEUS: study of deeply bound kaonic nuclei. DANTE: measurement of nucleon timelike form factors.

Page 4: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

4B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

KLONE group

• Funding: Use as much as possible already existing material. Got some INFN funds: CSN5, DR LNF, KLOE, AMADEUS. Got CEE funds via TARI projects.• A lot of help for: Mechanic: G.Bisogni, U.Martini et al. Electronics: A.Balla et al. Detector support: M.Anelli, A.DiVirgilio et al. Transports: M.Rossi, P.Caponera.• Interesting and useful interactions with TSL group.

Page 5: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

5B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Neutron source (TSL)• Neutron beam from 178.8 MeV protons on 7Li target.• 42% of neutrons at max energy.• Calorimeter at 5 m from target.• Absolute neutron flux in the peak measured after the last collimator by 3 beam intensity monitor: better accuracy 10%.

EKIN (MeV)

Page 6: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

6B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Experimental setup and data set

(1)

(3)

(2)

1. Old KLOE calorimeter prototype, 3×5 cells (4.2×4.2cm2), 60 cm long, read out at both ends by Hamamatsu/Burle PMTs.2. Beam position monitor: array of 7 scintillating counters, 1 cm thick.3. Reference counter: NE110, 5 cm thick, 10×20 cm2.A rotating frame allows for vertical (data taking with n beam) and horizontal (for calibration with cosmic rays) positions.

• 3 large data sets collected with different beam intensity: low (1.5 kHz/cm2), medium (3.0 kHz/cm2), and high (6.0 kHz/cm2)• For each configuration, several trigger threshold scans.• Typical run: 0.5-1.5 Mevents, 1.7 kHz DAQ rate.• Cosmic rays run (beam off) for calibrations with MIPs.

Page 7: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

7B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Method of measurement

fLIVE

Thr (mV)

= RTRIGGER

RNEUTRON × fLIVE ×

RNEUTRON: From beam monitor via neutron flux intensity measured by TSL. RTRIGGER: use coincidence between sides.• Scintillator: T1 = Side 1×Side 2.• Calorimeter: use the analog sum of 12 PMs/side (first four planes); sum are first discriminated and formed: T1 = A×B

fLIVE: live time fraction : for preliminary measurement, assume full acceptance and no background.

Global (no energy dependency) efficiency measurement:

Page 8: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

8B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Scintillator efficiency - 1Good check of the measurement method, even if the live time fraction is high in almost all acquired runs.Calibration of the energy scale with a 90Sr source.10% accuracy for both vertical () and horizontal (Threshold) scales.

Thr (MeV e equiv. energy)

(%)

Page 9: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

9B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Scintillator efficiency - 2The comparison with previous published measurements in the same energy range, by scaling them to our thickness, is good within the errors. Agrees with thumb rule (1%/cm): 5% for 5 cm thick scintillator (with a threshold of 2.5 MeV electron equivalent energy)

Thr (MeV e equiv. energy)

(%)

Page 10: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

10B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Calorimeter efficiency - 1

• Energy scale set using the conversion factor from KLOE.• 10% uncertainty on both horizontal and vertical scales.

• Stability wrt very different run conditions: a factor 4 variations of both live time fraction (e.g. fLIVE=0.2 0.8) and beam intensity (1.5 6.0 kHz/cm2).• Small efficiency decrease with high beam intensity; possible pile-up effects, have to be studied.

(%)

Thr (MeV e equiv. energy)

Page 11: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

11B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Calorimeter efficiency - 2

• Very high efficiency, about 4 times larger than the expected if only the amount of scintillator is taken into account: 8% for 8 cm of scintillating fibers.

• Compare with our scintillator efficiency measurement, scaled by the scintillator ratio factor 8/5

(%)

Thr (MeV e equiv. energy)

Page 12: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

12B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Neutron spectrum from ToF - 1

n

a) b) c)

d)For the 3 cells of first calorimeter plane:• Correct raw spectra (a) for T0 (b) and convert into ns (c)• TDC spectra of single cell show a 41 ns time structure (from phase locking). • Has to be corrected for wrong clock association (d).• At 5 m from target, rephasing needed for n kinetic energies less than 50 MeV.

Page 13: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

13B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Neutron spectrum from ToF - 2e) f)

EKIN (MeV)

• From ToF spectrum obtain velocity spectrum (e).• Assuming neutron mass determine kinetic energy spectrum (f).Compare with the input theoretical n spectrum.

The “per cell” exercise has to be repeated for the whole calorimeter after the cluster procedure definition.

Page 14: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

14B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Data – fast MC comparison

For the central cell of the first plane, compare data with fast MC.

Assume a n efficiency as function of the kinetic energy.

Data-MC comparison of time, velocity, and kinetic energy distributions (dots are Data, line is MC).

Other shapes of the efficiency curve have been tested, obtaining a worse agreement between Data and Mc.

EKIN (MeV)

EKIN (MeV)

ns

(EKIN)

Page 15: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

15B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

MC: detailed simulation

7Li Target

Shielding(concrete and steel) Calorimeter

Using Fluka code, simulate a detailed description of the main elements of the beam line (source, collimator, shielding,…) and of the calorimeter:• KLOE simulation: lead-scintillator layers.• New simulation, using lattice tool, design the fiber-lead structure.

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B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Don’t interact: 14 %

Elastic (%) Inelastic (%)

Lead 32.6 (1.5) 31.4 (1.5)

Fiber 10.4 (1.0) 7.0 (0.8)

Glue 2.3 (0.5) 2.2 (0.5)

From the simulation of a sample of 1000 monoenergetic (180 MeV) neutrons: 10% elastic processes within the scintillator: could produce the “expected” efficiency. 31% inelastic processes within lead: produce the “unexpected” efficiency rise.The energy is deposited by photons and protons. Also low energy neutrons contribute because of the rise of n-p cross section for low energy neutrons.

In average, 5.4 secondary particles per primary n are generated in inelastic interactions, counting only neutrons above 19.6 MeV.

The interactions of low energy (En<19.6 MeV) secondary neutrons produce, in average, 97.7 secondary particles per primary neutron.

MC: physical processes

Secondary (%) (En>19.6MeV)

Secondary (%) (En<19.6MeV)

n 62.2 94.2

26.9 4.7

p 6.8 1.1

Page 17: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

17B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Conclusions and future plans

• The preliminary measurement of the neutron detection efficiency of the KLOE calorimeter, done using KLOE data, has been confirmed by the test beam at TSL.• The preliminary results show an efficiency 4-5 times larger than the expected if only the amount of scintillator is taken into account.• For comparison the efficiency of the 5 cm thick NE110 scintillator has been measured, and turns out to be about 5% as expected.• The results are in agreement with recent simulations based on Fluka. Complete simulations of the calorimeter and the beam line will allow to better understand the efficiency increase.• Apparently the inelastic interactions of the neutrons on lead produce a large amount of secondary particles. The high sampling frequency of the calorimeter allows the detection of such particles.• We plan to complete the analysis of TSL data in the next months.• A new test beam is foreseen (summer 2007) at Louvain (Belgium) to extend the investigation to lower kinetic energies (down to 10 MeV) and to improve the knowledge of the energy dependency of the neutron efficiency.

Page 18: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

18B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Spare slides

Page 19: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

19B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Neutron source details (TSL)Both TSL (Uppsala) and Louvain source look reasonable.Louvain could not be used before 2007 (TMAX=68 MeV)

• No beam extraction signal.• n are produced with proton on 7Li target, 3 m collimator, sweep magnet.• n energy peaked at cyclotron energy; low energy tail.• n timing phase-locked to main cyclotron RF with narrow pulse duration: TOF=1.53 ns.• Beam spot increases linearly with distance from target: use a circular collimator 2 cm diameter at 3 m.• Approved on 18 May 2006: code F183 assigned• Allocated beam time: 16-27 October 2006, 8 shifts of 8 hours assigned.• Cost: 400 Euro/hour (half paid on TARI)

Page 20: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

20B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Details on DAQ• Scintillator trigger: Side 1 – Side 2 coincidence (T1=S1×S2)• Calorimeter trigger: based on analog sum of the signals of the first 4 plan out of 5 (T1=A×B).• Trigger signal is phase locked with RF signal (T1 free).• Vetoed from retriggering by a 5-35 s busy signal and by the DAQ busy.• The final trigger signal is: T2 = T1free.AND.NOT(BUSY).

• T1free, T2, and the n monitor signals are acquired by a scaler asynchronous from DAQ.• Fraction of live time: T2/T1free; essential for the efficiency evaluation.

T2/T1FREE

Thr (mV)

• Neutron rate proportional to neutron monitor via neutron flux intensity (I0) and peak fraction (fP)• An absolute rate calibration should be provided by scintillator counter.• Calorimeter scintillator efficiency rate is almost independent from beam monitor.

Page 21: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

21B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Time structure

4.2 ms

2.4 ms

40 ns41 ns

5 ns FWHM

RF Macro structure

Calorimeter Trigger signal

Page 22: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

22B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Test of phase locking

Beam RF

T1(Free)

Test done with a random trigger at 60KHz

Page 23: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

23B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

S1(ADC counts)

Thr (mV)

1.15 count/mV

1.02 count/mV

S2(ADC counts)

Thr (mV)

Trigger threshold calibration: mV to ADC counts

Scintillator calibration source to set the energy scale in MeV: 90Sr endpoint 0.564 MeV; 90Y endpoint 2.238 MeV.Fit of the b spectrum, with ADC counts to MeV factor as a free parameter.

0.021 MeV/count

0.023 MeV/count

ADC counts

S1

S2

ADC counts

Page 24: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

24B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Calorimeter calibration

A 1.6 count/mVB 2.0 count/mV

AD

C c

ount

smV

• Cell response equalized: MIP peak at 600 ADC counts.• Trigger threshold calibration: - HP attenuators used for A and B not to exceed the dynamic range of the ADC; different attenuation factors: fA=2.0, fB=1.7. - Threshold in counts studied with different methods.• Energy scale set with MIPs using the conversion factor from KLOE: a MIP in a calorimeter cell corresponds to an electron of 35 MeV.

Page 25: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

25B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Raw TDC spectrum, no T0

Page 26: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

26B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Raw TDC spectrum, T0 corr.

Page 27: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

27B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

TDC spectrum, not rephased

Page 28: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

28B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

TDC spectra, RF rephased

Page 29: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

29B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Velocity spectrum

Page 30: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

30B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Kinetic energy spectrum

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31B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Data – fast MC comparison - 2

Worse agreement if we assume an efficiency increasing with energy.

EKIN (MeV)

EKIN (MeV)

ns

(EKIN)

Page 32: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

32B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Clustering

For each side: group adjacent cells in “side

cluster”.

For event with at least a “side cluster” on each side, compute

“event cluster” information.

Page 33: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

33B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Weighed energy average on cell:

cellecella

cellecellacella

clu E

EXX

0X

Side A: x and z coordinates

0

Z

cellecella

cellecellacella

clu E

EZZ

Page 34: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

34B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

cellecella

cellecellacella

clu E

ETT

Weighed energy average on cell:

celle

cellaclu EE

Sum of cell energies:

Side A: time and energy

Page 35: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

35B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

n BCLU

ACLUFclu TTvY

2

1

Cluster: coordinates

SideSide

SideSideSide

clu E

EXX

SideSide

SideSideSide

clu E

EZZ

Y

XZ

0

0

Page 36: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

36B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

F

CALO

SideSide

SideSideSide

clu v

L

E

ETT

2

Side

Sideclu EE

Cluster: time and energy

Page 37: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

37B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Signal development time - 1

n

Time difference between a cluster in one of the first four plans (trigger) and one in the fifth plane.As a reference, KLOE expected time resolution for 5-20 MeV photons is 0.8-0.3 ns.

ns

Page 38: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

38B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Signal development time - 2

nsns

Difference between the cluster time (computed as energy weighed average) and the time of the cell making up the cluster itself.As a reference, KLOE expected time resolution for 5-20 MeV photons is 0.8-0.3 ns.

Page 39: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Energy response

Side

Sideclu EE

180 MeV neutrons

• MC energy distribution is too broaden and no energy direct measurement can be done.• Little correlation between released and incident energies.• Data energy distribution peaked at 20 MeV.

Page 40: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

40B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Calorimeter details

1.2 mm

1.35 mm1.0 mm

• 1 mm diameter scintillating fiber (Kuraray SCSF-81, Pol.Hi.Tech 0046), emitting in the blue-green region, Peak<460nm.• 0.5 mm lead grooved layers (95% Pb and 5% Bi).• Glue: Bicron BC-600ML, 72% epoxy resin, 28% hardener.• Core: polystyrene, =1.050 g/cm3, n=1.6• Cladding: PMMA, n=1.49• Only 3% of produced photons are trapped in the fiber. But: small transit time spread due to uni-modal propagation at 21, small attenuation (=4-5m), optical contact with glue (nGLUEnCORE) remove cladding light

TR = 21 TR = 21

cladding

core 36

Page 41: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

Details on calorimeter simulation• Old simulation: lead-scintillator layers (GEANT3)• New simulation: with FLUKA, using lattice tool, the fiber-lead structure has been designed and replicated 200 times.• Active material (fibers + cladding): polystyrene C2H3 homogeneous material with =1.044 g/cm3 (average between cladding and core).• Passive materials: lead foils, 95% Pb and 5% Bi homogeneous compound.• Glue: 72% epoxy resin C2H4O, =1.14 g/cm3, 28% hardener, =0.95 g/cm3, hardener details:

GLUE FIBRES LEAD

Base module (198 fibers):

200 layer replicas:

Polyoxypropylediamine C7H20NO3 90%

Triethanolamine C6H15NO3 7%

Aminoehylpiperazine C6H20N3 1.5%

Diethylenediamine C4H10N2 1.5%

Page 42: B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee1 Neutron detection efficiency of the KLOE calorimeter B.Sciascia (LNF  INFN) for the KLONE

B. Sciascia 27 November 2006, XXXIII LNF Scientific Committee

without Birks effect

• Birks effect is important for neutron detection: the energy is released essentially by protons.• Birks parameters highly dependent from the scintillating material• Can be measured on KLOE data using protons from Dane machine background (photo production on beam pipe and quadrupoles), see: C. Bini, www.lnf.infn.it/kloe/private/memo/km330.ps

MC details: Birks parameters