The performance of the LHCf detector 16 Nov 2009 Kentaro KAWADE - - PowerPoint PPT Presentation

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The performance of the LHCf detector 16 Nov 2009 Kentaro KAWADE - - PowerPoint PPT Presentation

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The performance of the LHCf detector 16 Nov 2009 Kentaro KAWADE M1 Nagoya University Solar Terrestrial Environment Laboratory for the LHCf collaboration

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SLIDE 1

The performance of the LHCf detector

16 Nov 2009 Kentaro KAWADE M1 Nagoya University Solar Terrestrial Environment Laboratory for the LHCf collaboration

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SLIDE 2

What is the LHCf experiment?

UHECRs (Ultra high energy cosmic rays) are observed by many

  • experiments. (Auger,HiRes,AGASA)

But, there is the uncertainness of the model of cosmic ray and atmosphere interaction.

LHCf will give calibration data for such interaction models by measuring in CERN LHC.

空気シャワー 図 宇宙線シャワーの概念図 図 電磁シャワーとハドロンシャワー

LHCf physics goal is to provide critical calibration data for the hadron interaction model used in cosmic-ray physics and to understand the essence of high energy cosmic rays.

宇宙線 図 宇宙線のエネルギースペクトル

←LHC energy LHC:7TeV + 7TeV

  • >10x1017eV@Lab Sys
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SLIDE 3

LHCf Detector

 LHCf has two independent

  • detectors. (Arm1 and Arm2)

 two towers of sampling imaging

calorimeter, and Front Counter.

Arm1 Arm2

Arm1 Detector 20mmx20mm+40mmx40mm 4 XY SciFi +MAPMT Arm2 Detector 25mmx25mm+32mmx32mm 4 XY Silicon strip detectors

Longitudinal size (mm)

50 100 150 200

Vertical size Detector#1 Scintillator Tungsten SciFi 20, 40 mm Longitudinal size (mm)

50 100 150 200

Vertical size Detector#2 Scintillator Tungsten Silicon 25, 32 mm

16 Scintillators & Tungstens 4 SciFi or Silicon total 44r.l.,1.7 λ Front counter

Arm2 Arm1 SciFi & Silicon detector

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SLIDE 4

Location of Detector

 LHCf experiment located

near IP1.

 Detectors are installed in

both sides of IP1 covering the 0 degree of collisions, 140m away from IP1.

Arm1 Arm2

→IP1

←beam beam→

Interaction Point Arm1 Detector Arm2 Detector 140m 140m

TAN TAN 96mm

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SLIDE 5

Beam test @ CERN SPS

We tested The performance of LHCf @CERN SPS (North Area T2-H4 beam-line ) in 24 Aug - 11 Sep 2007

Beam enters along the red arrow.

Trigger by two trigger scintillators.

Particle incident position was measured by Silicon tracker (ADAMO)

0mm 730mm 1050mm

}

silicon tracker (ADAMO) LHCf detector Movable stage trigger scintillator Beam Setup of the SPS test

Beams used in the test Electrons; 50-200 GeV Hadrons; 150 and 350 GeV Muons; 150 GeV

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SLIDE 6

Result

 The energy and position

resolution are confirmed with the beam test. →good agreement with the MC simulation.

Arm1 Arm2 ΔE <5% <5% Δx <200um <60um linearity <5%@7TeV <5%@7TeV trigger threshold >100GeV >100GeV pseudo-rapidity ∞>η>8.4 η>8.4

[Energy] [Position]

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SLIDE 7

Front Counter

The Front Counters (FC) are inserted in front of Arm1 & Arm2 calorimeter.

To reduce background event from beam & gas collisions, FC are installed.

Beam & Gas BG is generated by the collision between Proton beam & residual gases in the beam pipe.

検出器

!"#$ !#$ %&'()&*+,&- .#/'(/**0(&)+%012 3345#$

図 の外観 図 シンチレーターの配置

4x Scintillators & a copper plate aperture = 64cm2

s as

5*6*06 716%8*6*06

)*+,%9%.+/%:; /*0148+<=%>+<6302*/ )*+,-.+/%01223/314

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SLIDE 8

The performance of FCs

Beam-gas BG particles emitted one side of IP1. So beam-gas BG can be reduce by coincidence

  • f both calorimeters

But detection effjciency decreases, because the aperture of calorimeter is limited. ←use Front Counters. We calculated the performance of the FC by MC simulation.

p-p p-gas S/N Arm1 1.37x10-1 3x10-4 4.5x102 Arm2 2.07x10-1 3x10-4 6.9x102 Arm1*FC2 8.8x10-2 3.8x10-6 2.3x104 Arm2*FC1 1.2x10-1 3.8x10-6 3.2x104 Arm1*Arm2 2.6x10-2 3.8x10-6 6.8x103 <detection effjciency & S/N ratio>

!"#$%&'&" () *+$,%-"."/.0+ *+$1%-"."/.0+ !"#$%&'&" () *+$,%-"."/.0+ *+$1%-"."/.0+

beam & gas collision beam & beam collision

60% 1/100 ×50

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SLIDE 9

summary

 The performance of LHCf calorimeter was tested at CERN

SPS in 2007. For electron of 50-200 GeV, the energy and position resolution are confirmed, & these are in good agreement with the MC simulation.

  • > Energy resolution :<5% for gamma ray
  • > Position resolution : <200um for gamma ray

 By using the FC in coincidence, 60% of signal event can

survive & can reduce the background to 1/100. This corresponds to the improvement of the signal to BG ratio by a factor of 50.

 LHCf detector is already installed in the LHC tunnel and

ready to take data once LHC restarts in this winter.

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SLIDE 10

Thank you

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SLIDE 11

The performance of FC

We calculated the performance of the FC by MC simulation.(Table1)

It is conclude that by using the FC in coincidence, 60% of signal event can survive & can reduce the background to 1/100.(Table2)

Minimized the bias of coincidence in analysis.

Because it is assumes that the vacuum level of the beam pipe get worsen by 100t imes, it can be said that the FC is useful.

coincidence condition Arm1 Arm2 W/O coincidence 13.7% 20.7% Arm1 & Arm2 2.6% 2.6% Arm1 FC & Arm2

  • 8.8%

Arm1 & Arm2 FC 12.0%

  • <Table1. The detection effjciency for p-p collision>

p-p p-gas S/N Arm1 1.37x10-1 3x10-4 456.6 Arm1*FC2 8.8x10-2 3.8x10-6 23157.8 <Table3. S/N ratio before & after coincidence> 50.7 times improved <Table2. Detection effjciency of beam & gas BG> single detect coincidence detect Start up 3x10-4 3.8x10-6 Stable 7x10-5 3.7x10-7

table1,2いらない

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SLIDE 12

S/N of beam-pipe BG

 We calculated the signal to

BG ratio by using MC simulation.

 Setting the threshold

energy to 150MeV, we can reduce the ratio to 1.2%.

第 本番実験のシミュレーション

Trigger threshold [MeV] 50 100 150 200 250 300 350 400 BG/Gamma Ratio

  • 2

10

  • 1

10 1

BG/Gamma Ratio

図 検出器の カロリメー タにおける、ディスクリレベル毎のバックグラウンド 粒子 線イベントの比。トリガー条件は、 層連続 コインシデンスであり、シンチレータでのエネルギー 損失相当でディスクリレベルを設定している。例え ばディスクリレベルを 相当に設定した場合、 バックグラウンド粒子 線イベントは となる。 図 検出器の カロリメー タにおける、ディスクリレベル毎のバックグラウン ド粒子 線イベントの比。例えばディスクリレベル を 相当に設定した場合、バックグラウンド 粒子 線イベントは となる。 いる。バックグラウンド粒子 線イベントの比で、約 相当のディスクリレベルにて折れ曲がり が見られるのは、ちょうど約 の 線を境にイベントのカットが行われるからである。 図 は、 検出器の つのカロリメータで検出される、全ての粒子に対する検出レートをディ スクリレベル毎にプロットした図である。 のルミノシティを仮定し、 陽子同士の非 弾性衝突断面積を と想定している。図より約 相当のディスクリレベル以上では、検出レー トはなだらかに推移し、 以下のレートで検出できることがわかる。 検出器側の システ ムの限界処理レートである に対しては、 以上相当という低いディスクリレベルで下回る ことが出来る。上記と同じく、例えば 相当にディスクリレベルを設定した場合、 の検出 レートが得られる。しかし、検出レートはルミノシティの値にそのまま比例するため、加速器の運転状況 により柔軟に判断する必要がある。この理由により、私は実験前よりディスクリレベルを つに絞り、最 適化することは容易にすべきではないと判断した。その代りに、運転中にバックグラウンド粒子 線の比 及び検出レートを参照できるテーブルを作成することとした。これは、ディスクレベルを現場で柔軟に変 更するための重要な情報となる。 ここで、 検出器も含めた つのカロリメータに対して同様に行った、残りの解析結果を載せる。 図 は、 検出器の カロリメータのエネルギースペクトル及びトリガー効率であ る。図 は、それぞれ 検出器における 及び カロリメータに おける、ディスクリレベル毎のバックグラウンド粒子 線イベントの比である。図 は、 検出 器におけるディスクリレベル毎の検出レートである。図 は、それぞれは 検出器の 及び カロリメータにおける、ネルギースペクトル及びトリガー効率である。各図 の表記の仕方は、図 と同様である。 検出器においては、図 から分かるように、検出レートが 検出器側よりも大きい。こ れは第 節で説明したように、 検出器の方が 検出器に比べ、粒子の入射位置分布に対す

1.2% 省く

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SLIDE 13

The beam pipe background

 By collision between

secondary particle from p- p collision and beam-pipe inner wall, the background are generated.

 We can reduce that, by

setting the threshold level

  • ver 100GeV.

!"#$%&'&" ()*$%+,+%-*..'/'*0 1"#$%&'&"%!#-23)*405

100 GeV Full MC Simulation

<Fig.1 Energy Fluence>

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SLIDE 14 B.Beam & gas background The beam & gas background is the particles generated by the collisions between the proton beam and the molecules of residual gas in the beam pipe. In these collisions, because the protons have high energies and the gases are almost at rest, the secondary particles are emitted along the beam direction. Therefore, by taking coincidence between the Arm1 and Arm2 detectors, these background could be reduced. However, because the aperture of the calorimeters is limited, the efficiency for the coincidence events will be small and it will result a bias in the
  • analysis. To solve the problem, we made additional detectors
having larger aperture. That is Front Counter. The Front Counters are inserted in front of the Arm1 and Arm2 detectors. The definition of detection at Front Counter is that the energy deposits exceed 0.302MeV in both layers. A.The beam pipe background One of the backgrounds is the particles generated by the collisions between the secondary particles of p-p collisions and the beam pipe inner wall. It is called the beam pipe background.

Energy resolution Position resolution

The performance of the LHCf detector

Kentarou KAWADE STEL Nagoya Univ. for the LHCf collaboration

What is the LHCf experiment? The LHCf Detector

Interaction Point Arm1 Detector Arm2 Detector 140m 140m

The ultra high energy cosmic rays(UHECRs) are the key to understand the mechanism of propagation, direction and acceleration of cosmic rays. Therefore, they are observed by many air shower experiments, for example, Auger, HiRes and AGASA. The UHECRs are observed at surface as secondary cosmic ray. The way to know the information
  • f primary is reconstruction with a hadron interaction model by MC simulation. But, there is the
uncertainness of model. And it causes systematic errors of air shower simulations in high energy
  • region. To solve the problem, the LHCf experiment measures energies and transverse momenta of
neutral particles emitted in the forward region of 7TeV+7TeV proton-proton collisions at LHC. LHCf will give a crucial calibration point for the hadron interaction models used in the cosmic-ray physics.

The performance of the LHCf detector

LHCf has two independent detectors named Arm1 and Arm2. Both detectors have two sampling imaging shower calorimeters. Detectors are installed either side of IP1 covering the 0 degree of collision (pseudorapidity !>8.4). The performance of the LHCf detectors were tested at the CERN SPS North Area T2-H4 beamline from 24 Aug . 11 Sep 2007. The designed energy and position resolutions of <5% and <200!m, respectively, at >100GeV, were confirmed with the beam test. These performances are well explained with the MC simulation.

Backgrounds

We studied these backgrounds by means of MC simulation. The software and the hadron interaction model used in this study are EPICS and DPMJET3, respectively. The structure of the LHC beam pipe, the dipole magnets and the LHCf detectors are considered in the simulation. There are two backgrounds, "A.The beam pipe background" "B.The beam & gas background". "#$%&'('# )*+%&,-,&.+//(0(+1 2#$%&'('#&"$.34*+516 Trigger threshold [MeV] 50 100 150 200 250 300 350 400 BG/Signal Ratio
  • 3
10
  • 2
10
  • 1
10 <BG7 to Signal7 Ratio> 1.2% 100 GeV Full MC Simulation <Fig.1 Energy Fluence> <Front Counter> 40m 80m Scintillators (2.0mm thick) Copper plate (0.5mm thick) Light guide beam-gas collision Detect Not detect beam & gas BG secondary particles Thus, by setting the threshold energy at 100 GeV, we can expect effective collection for the collision events and rejection for the background events. The trigger is issued when more than 3 successive calorimeter layers record signals over a certain threshold level. We tested the background to signal ratio as a function of this threshold level(right down figure) by full MC simulation. In the LHCf operation, this threshold level is set at 150MeV that realizes a sufficient efficiency for 100 GeV incident gamma-rays. At the threshold level of 150MeV, the background to signal ratio is 1.2%. This is a robust result for the fine tuning at the actual operation because the background to signal ratio has a weak dependence on the threshold level. Furthermore, because these background events concentrate in the lowest energy, the effect of the beam pipe background is negligible in the final LHCf analysis. The experimental target is gamma-rays >100GeV and neutrons >1TeV Detector = SAMPLING CALORIMETER scintillaor:16layers 89Arm1 20mm:&40mm:;&Arm2 25mm:&32mm: tungsten: 16layers (total 44 radiation) We calculated the detection efficiency of each detector and coincidence condition by full MC simulation. The results are showwn in Table1. By using the Front Counter in coincidence, 60%
  • f the single side events can survive and we can minimize the
bias of coincidence in analysis. The right figure shows Energy fluence of the beam pipe background and photons from IP at the calorimeter. The fluence of beam pipe background peaks below 100GeV and rapidly decreases over that energy while the gamma- rays from p-p interactions distribute above 100GeV. 0.007% 0.03% Single detect 0.00037% Stable 0.0038% Start up Coincidence detect <Table2. The detection efficiency for the beam & gas BG> 12.0%
  • Arm1 Calorimeter & Arm2 Front Counter
  • 8.8%
Arm1 Front Counter & Arm2 Calorimeter 2.6% 2.6% Arm1 Calorimeter & Arm2 Calorimeter 20.7% 13.7% Without coincidence Arm2 Arm1 Coincidence condition <Table1. The detection efficiency for p-p collision> We estimated the detection efficiency of the coincidence between the calorimeter and the Front Counter for the beam&gas background by Full MC simulation(Table2). By the results, we confirmed the coincidence detection can reduce the beam&gas background to 1/100.
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SLIDE 15

What is the LHCf experiment?

UHECRs(Ultra high energy cosmic rays) are observed by many experiments. (Auger, HiRes and AGASA.)

The UHECRs are observed at surface as secondary cosmic ray. The way to know the information of primary is reconstruction with a hadron interaction model by MC

  • simulation. But, there is the uncertainness of

the model. And it cause systematic errors of air shower simulation in high energy region.

To solve the problem, the LHCf experiment measures energies and transverse momenta

  • f neutral particle emitted in the forward

region of 7TeV + 7TeV proton-proton collisions at LHC.

LHCf will give a crucial calibration point for the hadron interaction models used in the cosmic-ray physics.

宇宙線 図 宇宙線のエネルギースペクトル

空気シャワー 図 宇宙線シャワーの概念図 図 電磁シャワーとハドロンシャワー
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SLIDE 16

Construction of detector

 The experimental target is gamma-rays > 100GeV

and neutron > 1TeV.

 We have two towers of sampling-calorimeters

%%

検出効率の算出 表 コインシデンス条件 検出器 検出効率 %

Arm1 calorimeter 13.7% Arm2 calorimeter 20.7% Arm1 Front Counter 63.7% Arm2 Front Counter 64.3%

表 5.3: 検出効率

検出効率の算出

の検出効率、 カロリーメーターの検出効率、 また両 での コインシデンスイベント、 とカロリーメーターとのコイン シデンスイベントの検出効率を算出する。検出の条件は以下である。 カロリーメーター 層のシンチレーターのうち一層でのエネルギー損失が三層連続で を超える。 一層目のどちらかのシンチレーターと二層目のどちらかのシンチレー ターでのエネルギー損失が 。 一層目のどちらかのシンチレーターと二層目のどちらかのシンチレー ターでのエネルギー損失が 。 コインシデンスをとる場合は各検出器の検出条件を合わせる。コインシデンス の条件は表 にしめした。 は と のカロリーメーターによるコイ ンシデンスであり、 は カロリーメーターと とのコイ ンシデンスである。また は カロリーメーターと との コインシデンスであり、 は と の のコインシデンスで ある。以下でコインシデンス条件はこの表の番号で呼ぶことにする。 全 回の衝突のうち検出された事象数の比を各検出器単体で表 に示し た。この結果によるとカロリーメーターについて と では検出効率に の差がある。これはカロリーメーターの有効面積の差であると考えられる。

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SLIDE 17

Detectors

Arm#1 Detecor Arm#2 Detector

90mm 2 8 m m

slide-18
SLIDE 18

The running plan

 2009 Nov Beam commissioning  2009 Dec collision 450GeV & 1.1TeV  2010 Feb 3.5TeV collision & upgrade detector  2011 5-7TeV collosion?

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SLIDE 19

Discrimination of hadron interaction model

 Statistical error bars are

assigned assuming corresponds to about 103 seconds at the luminosity of 1029/cm2/s.

 This is achieved at the very

early phase of LHC.

 only with a short operation,

the existing models are clearly discriminated.

expected energy spectra of single gamma-rays at LHC 14TeV collisions.