 Thank you. So, good morning everyone. So, I'm Toshiyasu Nami from the Radiation Science Center of the Digital Laboratory of High Energy Accelerator Research Organization, K-E-K, that's in Japan. And it's shown here that we also operate some of these graduate schools for the graduate students. And then my talk is the double differential cross-section measurement for charge particle production reaction by grid ionization chamber. As you may know, most of the topic is already covered by two lecturers yesterday and the day before yesterday, so I'm sorry, several overlap I have. So, the double differential cross-section measurement for the charge particle production reaction by grid ionization chamber. I will talk about this topic as an example of this, the measurement of the double differential cross-section heading production, that's alpha production for the several MEB neutron induced reaction. That's one of the topics for the measurement of N-alpha reaction cross-section. And then this is a brief summary of why do we need to measure the N-alpha DDX. That's already mentioned by lecturers. So, mostly the data for high energy, I mean it's not high energy, it's a fast neutron. That's a 14 MEB, that's because we want to plan to build a DT fusion reactor design and we need data for the, as well as operation. That's because we have to estimate the damage of material due to the accumulation of gas, actually the alpha is the helium so that we have a serious damage if the accumulation of the gas. And also we have to estimate the nuclear heating, that's because we developed a fusion reactor and the fusion process, the most of the energy going out with neutrons. So, we have to estimate how much neutron deposits the energy where and when. That's the reason we need the basic data of W differential cross-section. That W differential cross-section is not only the amount of reaction also, it's the energy and also the angle distribution so we can do the full simulation. That's in our art, that one, the design is the neutronics. So, the neutron transport and then energy deposition or the reaction, that's the total design we need. So, that design, the W differential cross-section of NLP is very important. So, to measure the W differential cross-section, what item do we need? Of course we have to produce neutrons for suitable energy. Typically the 4MVB to 40MVB for example, that's because 40MVB is the upper limit of fusion, DT reaction and then the 4MVB is close to the threshold if we assume the structure material NLP cross-reaction. That's because the NLP reaction, the alpha particle when they try to go out so the alpha particle feed some of the current barrier so there is some threshold. So, the neutron production, we have to know the neutron production reaction. We already had a very nice lecture on hands-on training yesterday and then that's maybe you guys know the detail of the neutron production reaction. So, slightly repeat that part and also that we have to measure the neutron that's because we have to normalize the cross-section that is also an issue to determine the absolute value of W differential cross-section. To design the experiment, we have to estimate yield. Can we measure the particle, how much particle we're going to have or we are using our detector so the yield estimation, I talk about that. And then to design the yield, determine the yield estimation that's these two important parameters. One is the target thickness, the other is the detector's return. Then we prepare the detector. So, firstly I talk about the grid radiation chamber and then outline the electronics and analysis I will talk about. So, first the neutron production. So, the neutron production reaction measurement. So, now a facility as a very common use, sorry, three or four megabot, it's an electrostatic accelerator. So, this is the plan view of our facility. Actually, it's not our facility, that's not high energy, that's low energy facility. And then whenever the university student that play around the facility, you can see that here is accelerator tank and that's 4.5, it's dynamitron actually. And then this is analyzing magnet and we have 0 degree and 50 degree and 30, 45 and 60 degree port. So, in past the facility is mainly for the neutron interaction, neutron cross-section measurement. So, you can see it's too small, I'm sorry, that's two ports or dedicate for the neutron science. One is the 15 degree and the other is the 30 degree. And 15 degree we have the goniometer and then that one is mainly for the neutron scattering experiment. So, we also measure scattering cross-section. So, NN dash or something like that. So, that case, you have this is the vacuum tube and we put the small target in here and also the sample in here and the detector is heavily sealed inside the goniometer. And the other port for the neutron is the 30 degree. That is, you can see, it's a relatively large space, that's for the multi-purpose. So, we put several equipment and then play around to hold the neutron measurements. And also, that's a gradient ionization chamber also operate in this port. The other two, 45 and 60, that's for material radiation. So, that's neutron science. So, the helium accelerated and then injected on the material and the people take a look, the sample damage was checked, it's stability or I don't know, it's some of the thing, the material realization. And this one is for material analysis. So, the RBS port. But this one, this configuration is already gone. Nowadays, the neutron interaction is not so important at this moment. So, the operation is completely changed. So, this port is disappear and then replaced to the PICC. PICC means the PIXE, the proton induced X-ray emission. That is also analysis technique. So, that one is, the port is for PICC and this one is PICC. So, only one port for the multi-purpose neutron experiment. But still ongoing. So, to generate the neutrons, the following is a typical reaction. So, already explained by Rexchela. So, for the purpose of the structure material in our cross-section measurement. So, normally we use the TDN or DDN to cover the four to six. Actually, that's if our accelerator operates same as a spec. So, maybe it's reached to seven or eight. But our accelerator is very old. So, reach to the six or something like that. And TDN, normally we use the 40.1. That's because it's in zero daily. You can calculate by using the yesterday's computer program. So, you can set the 90 degree that you may have the much sharp neutron energy of 14.1 MeB at the 90 degree or 100 degree or something like that. The target is the titanium 3-cherm fall. And in DD reaction, we use the D2 gas target. So, what is the important thing is this intensity. This is, of course, it depends on the target condition. If we use the much thicker target, so maybe you have so much neutron, but the energy width is very broad. So, that's how you can adjust whether you want to measure or whether you want how much resolution you need. So, then the target thickness control is very important. So, anyway, so the order, the target and the order of magnitude is 10 to the 4 or 10 to the 5 at 10 centimeter from the target. So, you can estimate your yield based on these numbers. And this is unit. So, that's a neutron per square centimeter per microcron so that if you have one microampere, that's the typical beam current of the accelerator. So, you may have these number of neutrons. And a little bit detail about the target structure. That's because the yesterday poster that I saw, there are many, is a target structure. Our target system is very small and thin. That's because we don't want to scatter component around the target. So, here is, this one is a gas target. So, the menu for the D2 gas and DD reaction. So, our cell is roughly this 3 centimeter and this is the foil to separate the gas part and the vacuum part. This is the molybdenum foil. That may be common. That's a 5 micrometer. I'm sorry, that's not millimeter. That's 5 micrometer. And we used to use the harbor foil also. That's a 2.2. It's micro, I'm sorry. That's a micrometer foil. But beam current problem we have that we want to increase the neutron yield. So, easiest way is just increase the number of deuteron so that we increase the deuteron beam current. But it's harbor foil is not so strong. So, according to our experience, maybe 1 or 2 microampere beam is the limit for the foil. But we need more. So, in that case, we use the molybdenum foil and the 5 micrometer. That's accept for 3 or 4 microampere. That will be 2 times more. And then the other structure is here. You can see the insulator and then there's a small tip in here. That is the aperture. So, we need to make sure that all the beam going to the target that's using this aperture. So, this aperture could connect to the current ammeter and then check how much it's current we're going to have during the operation. And here is the pipe to fill the D2 gas and then this gas filling system. That's very simple. Just make a vacuum by using a pump and then fill the gas and then measure the pressure. Titanium target. This is the titanium metal foil in here. Actually, this one needs the double tube to support the titanium foil. That's because one of the tubes is a blank structure and then put the titanium foil here and then there's another tube push and hold the titanium foil. That one is also the limit of beam current. Oh, I'm sorry. I skipped that one. Here. It's cooling by air. It's air jet. That's because we don't want to throw down the neutron by water so we use only air jet. The same thing for the titanium target. But if we accelerate, inject the neutron beam too much, the case, the titanium evaporated and then go to the accelerator side. So that one is also some of the limit up to four microampere. That's our experience, actually. So this is a typical spectrum of the 15 MAB case and 5 MAB case. Of course, that's a radius. It depends on the target condition. If we put so much neutron gas inside the target, so maybe the radius is broader. This one needs one atom case and a typical case. You can see the sum of the structure in here. That's because this one is a DT, so the deuteron hitting the trechium and then produce a zero degree, the 15 MAB neutrons. But we also have the DD reaction. That's because the deuteron injects to the target hole and then accumulates it. So the titanium also has a deuteron. That's because of the old target. So in that case, we also have the DD component. So every time we have to measure the deuteron spectrum by time-over-flight technique to ensure the energy and also the low-energy component. How to measure the deuteron spectrum we normally use, the NE213, that's very old, actually. Now it's a BC501AA, or let's say EJ301. Anyway, the recipe is the same. So the rigidity since you're done two-inch diameter and two-inch length are typically we use. That's because the simulator provides the deuteron gamma separation. That's very important. And then we put the simulator six meters or five meters away from the target and then the accelerator operates by pulse mode and then we do the time-over-flight to check the deuteron spectrum. So here is another idea to obtain the deuteron but it's a different energy. The one is the nitrogen 15 and deuteron and nitrogen 14, the deuteron. This provides the neutrons of 11.5 or 77.7 MeV. That's because our accelerator has not so high terminal voltage. So in that case, we cannot obtain the neutrons between 60, 6 and 14. So we can change the reaction. Of course, that one is not mono-energistic. That's because of the residual nuclei for example, 15, nitrogen, Dn. So we're going to have the 16 oxygen. So this is the level scheme of 16 oxygen so we can see the sum of the excited level. But the important point is the discrepancy between two levels. There's a large energy difference. It's a 6 MeV. So this is the time of flight spectrum for the 15 nitrogen, Dn reaction. So you can see the 11.5 MeV neutrons and then we have some space and then there's a much lower energy neutrons. So for application of the NRH reaction cross-section as I told you, the reaction cross-section has some of the threshold. If the threshold is higher than this energy so the neutron is no impact. So that source could be mono-energistic for that reaction measurement. But some of the case we have a small amount of reaction cross-section here. It's a 4 MeV or 5 MeV so we have to correct the effect by using the DD source. The DD source can provide the 5 MeV neutrons. But anyway, so this is one of the ideas to have the missing region, the 6 to 14 MeV. So 7.7 and also there's some of the structure. So let me talk about the easy estimation so the talk of the time of sickness and so on. So as the lecturer says yesterday so if we need the information only the total production so the activation method is one of the effective methods to measure an alpha reaction. But of course the residual should be radioactive and most of the case starts the material so residual is not radioactive so that case we can apply this one. And the other method is the helium accumulation which is the structure material sample packed the heavily and then it's irradiated by neutrons for a long time. I don't know the weeks or something like that. Then it's a accumulated helium measured some way. That's a helium accumulation method. These two can provide only total production. But we need the W differential cross-section so that case normally we use the counter-telescope method to measure the W differential. That's because the counter-telescope easily defines the angle and energy. So here is the schematic drawing of the experimental setup. So we have some beam from accelerator and then we can have the neutron production target. So the neutron production target provides neutrons and then we put target in some way away from this target, neutron production target and then the neutron induced alpha particle measured some of the detector. So when we want to know the W differential cross-section we can set the detector position around the angles and then it's so we can measure the W differential cross-section by using this small detector. But this experiment is a neutron experiment so we have to care the background. So always the neutron experiment we have to care the background. So the one is proton also produced and then emitted and then entered the detector and also the neutron is not collimated and then the directed heat detector or gamma also produced and affected the detector. Normally we use the detector for counter-telescope case so we use the detector as a semiconductor detector or this combination combined with a simulator. And we have to think about the solid angle that's because the detector size is too small and it's a bit far away. So how much particle can we measure by using this solid angle? That's an important factor. So first we have to think about the target. That the target means the sample to be measured for energy reaction so what we have to think about is one is the production rate. Of course we have to measure production rate so we don't know but we have some data to estimate the production rate so first we have to know the production rate and then it's energy resolution, what we need. That's because if we use the very thick target so the alpha particle emitted and then energy loss inside the target and then distort their own energy so that case we need to think about energy resolution what we need and also the background we have to take care and try to minimize the background. Once we use the thin target of course the counter-telescope should be low but energy resolution is high that's because of the energy loss within the target is minimized that's because of the thin target and also we need some backing foil so we have to think about the effect of backing foil that's because the thin target normally we use we prepare some of its backing foil and then put on by the vacuum evaporation some of the techniques and the very thin layer we build and then we're going to use so we have to take care of what backing foil we use and contrast the thick target that thick target is relatively thick that's not totally stopped but anyways that's a thick target case so that's a high counter-telescope we have but of course that's a degrade energy resolution and that's a thick target that self-supposed sample is available that's you can choose what we need the energy resolution, the production rate and the background we need to balance the parameter so yield estimation that's a very simple equation that's yield, multiply that number of atoms and cross-section and flux so let me think about the cross-section, the one band for example and neutron flux, we assume the DD neutron so that's at 10 cm for the target we have the order of 10 to the 4 neutron per square centimeter per second for example and the target thickness, in this case let's assume the one micrometer so that you can calculate how much atom we have this is also typical number, 10 to the 18 or 19 that's a typical sample number of atoms so you can multiply these three factors and then you have the yield so that case, the 0.2 alpha particle per square centimeter per second this number is not so large, you see that's 1 second, 0.2, but 4 pi so if you measure the alpha particle, the entire alpha particle but even in that case, it's 0.2 alpha particle per second which means the 720 event per hour so this is the typical condition of an alpha measurement so anyway, the problem is statistics so the solid angle, we have to take into account the solid angle, that's because now it's a 4 pi emission rate it's 720 per one hour experiment that's, you see, for example, so it's a silicon detector the typical area is 500 square millimeters that's commercially available it's either Ultec or Canberra or they provide the commercially available semiconductor detector with the area of 500 square meters that's the one inch diameter, corresponding to one inch diameter of course, the solid angle angular resolution, the trade-off if you want to maximize the solid angle so very close position, you have to put the detector and then that's the most of the particle you can measure but you may lose the angular resolution, totally so let's think about, that's a 10 cm away from the target and assume a 500 square meter so the solid angle is roughly 0.05 Stratian, for example this is the typical setup and then let's, angular radius is plus minus 7.2 degree that's not so small, right? your 30 degree data have with this, plus minus 7, right? in that case, we have the counting rate 36 count per hour, that could be acceptable maybe it's not so large, but it could be acceptable so how much, and then let's think about the energy loss in target so you may know that's very famous in the beta equation and our target is alpha particle measurements so up to 10 MeB, so beta is very small so we can neglect this part and then let's say the energy loss is proportional to G square and inverse proportional to V square but actually we don't need to calculate this the equation simply takes the data from data table where you can use the stream code, that's a famous code you can download and use this one the code says the alpha particle range in nickel for example, so 4.5 MeB, alpha particle the range is 8.04 micrometer in nickel so the 8.4 micrometer in nickel is enough to stop the 4.5 in other words or 5 MeB, that's 9.2 something, right? so which means if we enter the 5 MeB alpha particle in the nickel file and the thickness is 1 micrometer so let's take a look at the difference, it's 8 and 9 so we're going to have the 0.5 energy loss within the file it depends on what you need actually, so if you want to measure 5 MeB alpha particle with the 0.5, it's a 10% resolution so the 1 micrometer sample thickness will be acceptable but if not, so we have to reduce the target file thickness it depends on what you need so later I can show some of the examples for the 3 micrometer result and 0.3 micrometer result that's a significant difference between 2 and how much cross section we're going to have this is the condition, horizontal axis corresponds to the Newton energy that's 20 MeB, 10 MeB, 5 MeB cross section start and 3 or something like that and this is the cross section in burn so you can see most of the, this is evaluated data ENDF, Jeff and China data and Japanese data and there is some difference but anyway this cross section reach to 0.1 which means the 100 MeB the previous estimation I assume the 1 burn so it should be 10 times smaller so we need to improve the early estimation so the cross section goes to the 0.1 but the Newton flux we can increase that's because we can use the 3 micrometer beam for example so the 3 times smaller but target thickness the 2, 6 I think because of this 0.5 MeB, 10% is not acceptable that's because typical grid ionization chamber provides energy resolution of less than 2% or something like that we lose the sum of the information because of the target thickness we don't want so let's say 0.25 or something like that so if now for 4 pi per second is 0.015 and then let's assume the telescope so the 0.05 straight angle so the other result the ease should be 0.2 counts per hour that's not acceptable absolutely that because most of the event is background and nothing about the new alpha particle so this fact is main motivation to use the grid ionization chamber I think that's because the grid ionization chamber provides 4 pi straight angle so the count rate increase the multiple 4 pi so means that 54 counts per hour count rate that will be acceptable so everyone most of the person to measure the alpha particle by using grid ionization chamber that's because of the straight angle and in addition to that we measured alpha particle with 4 pi straight angle but we can distinguish the energy and angle at the same time that is also advantage of grid ionization chamber the other solution is just prepare the intense neutron source that's also good and this also works so for example the RANS group by using the counter telescope but they prepare much intense neutron beam and combine with the time of flight and then they provide very nice experimental data so let's start about the detector section so we have already done the yield and also neutron production and then we need to prepare the detector so first this is the typical as a counter telescope setup prepared by Los Alamos group they produce the intense neutron flux by using the RANS it's a WNR source and then the source is somewhere here actually as you can see it's 9.12 meter from the source here is the sample so that's because their source is not monolithic so the time of flight they need to analyze what neutron induced the reaction so here is the window and this is the vacuum chamber and here is the sample it's a target they say and you can see it's a 5 centimeter square it's a collimator and then it's 8.9 the diameter target but it has an angle and then here is the detector system they have 1,2,3,4 detector system and then each detector has the raw pressure the proportional counter and then silicon surface barrier detector and in addition to that it's not described but they have the CSI that's CSI simulator it's a three stage telescope and for neutron production they use the 800 MAB proton on tungsten targets so that's not monolithic and their course is 90 degree and the course provides 1 to 50 MAB neutrons with time of flight so this is the typical output of the detector system for example, so here the horizontal axis corresponds to the energy and the vertical axis corresponds to the energy loss so you can see that once we fix the energy but we may have several energy loss events that's because the different particles provide different energy loss so this is the typical particle identification of delta E and P methods so they only choose this alpha event and then make a spectrum and then make the cross section alright so let's move to the grid identification chamber so what is grid identification chamber you may already know, I'm sorry, it's an overlap section actually so the grid identification chamber is the parallel plate and the path mode identification chamber with grid so the ionization chamber you may know that the output signal depends on the position of the interaction later I will explain detail and then let's grid the ionization chamber just add the grid but we can remove the dependency by introducing the grid and then let's apply the grid ionization chamber for double differential cross section measurement so we're going to instill the sample it's a target on the cathode and then let's combine the anode and the cathode signal to deduce the energy and the angle that's already mentioned by the lecturers so this is the schematic diagram of ionization chamber so you can see here is the anode and the cathode that's a parallel plate and we have the voltage so we're going to have the electric field here for simplicity just ion comes from this direction parallel to the plate that's not real actually in any direction we're going to have but we assume the parallel ion beam so we have the capacitance and also we have the voltage and the number of ion pairs here that's because of the ionization and then there's the electric field here and here is the velocity and time for the electron and ion so we'd like to understand what kind of output from this setup so the easiest way is to think about the energy conservation law so the initial energy of this is a parallel plate we have the C and the applied voltage and then after it's a movement of the electron and ion to reduce the stored energy the remaining stored energy here and then it's the energy used for the electron drift the electron movement and also the ion movement this is a proportion to this the traveling distance so finally we have this equation that's a vr is the output so this is the voltage it's a transition the schematic view of the voltage transition here is the time and here is the voltage so first the electrons start moving that's because the electron drift velocity that's famous that's a microsecond per centimeter so one microsecond we need to travel one maybe opposite so the velocity the point is the ion velocity is a thousand times more so thousand times more is during the electron traveling the ion almost stops and not contributes to the signal so the first we have the electron contribution and then it's a thousand times later we have the ion contribution but the millisecond traveling time is not acceptable for us that's because the detector limited or the millisecond time response that's the counting rate determined by the traveling time so the millisecond traveling time means the kilo cps that's the counting rate is one thousand per second that's because the inverse of the millisecond so normally we operate the chamber with this mode that's we call the electron sensitive mode so that we can change the time constant of the leader to the electron system and then pick up the electron contribution only so the case you can see that the voltage caused by electron we have the x here x means the incident position of ion so it depends on the incident and the outside depends on the incident position of ion that's because the traveling distance could be changed so if we introduce the grid just before the anode so the situation needs to change of course we can the grid should be it's a we actually that's a several requirement we need so the add grid in front of the anode plate and then what happens is but before do that so yes that's a grid is said to be one is the transparent to electron we can choose the parameter which is the grid diameter and also spacing and also this electric field and then make transparent to electron and also the grid should shield the electric field between castle and grid to anode and grid so the grid should separate the ionization chamber to two space the different ionization chamber but same electron we use so that case the electron drift to the grid and then the grid is transparent to electron so the old electron pass through the grid and the tower to the anode so let's think about the between the grid and anode so the electron always travel from the grid to anode either x is 0 or x is called d that's because it's an electron this traveling distance still we have the difference between castle and grid but all the electron goes to the anode and the pass passing through the grid and then this distance is fixed to the situation that is the point of why we introduced the grid so what happened that is let's think about this part and then the ion injected in the grid ionization chamber and then ionization but we don't have any signal at this part that's because the electron start from here the tower to the grid that's the no influence of this part that's because the electric shield then the electron passing through the grid so the start signal and then always travel the same distance dAz so we can measure the number of electrons without considering the x value that's the point so to apply the method to the neutron cross section measurement so that case the neutron comes from this direction and then the red line that's the target and then here is the castle and this is the anode so just before the anode we put grid so the as I told you if the particle that's the alpha particle between the castle and grid so the produced electron always go passing through the grid and then reach to anode and then travel same distance dAz so that's a power side anode that's anode output is nearly equal to their energy but for castle they have some dependency that's because of the castle is a traveling distance as a function of the emitted angle if the same length, same energy so which means the same length of this range but the angle is small so it should be the travel distance is very short but the angle is very large so the travel distance nearly equal to d so the high output so that's dependency combine these two signals and then estimate their energy and angle so this is the actual instrument measure the newton ddx so you can see here this gas target and this one is connected to the accelerator so the d2 beam coming here and then produce a newton we put one collimator to collimate the newton and then irradiate this chamber so here is a sample so this one is a castle so here is anode but this one is a double sided that because we want to measure not only forward and also the backward angle then here is a grid and we have some of the structure to change the sample gear structure that's because we don't want to open the grid ion chamber to measure the background as I told you that we are going to use the same sample the same sample needs some backing so we need to subtract the backing effect so we measure not only the sample itself also the backing measurement and then subtract during the procedure we don't want to open the grid ion chamber so we need some structure to change the sample remotely from outside you can see the one more electron here that we called sealed that's because we applied the high voltage or anode plate and then this structure should be ground so we have the additional electron feed between anode and body so that makes signal so that we need to avoid the effect so we applied one of the electrodes which called sealed and then it has the same potential or anode so we don't actually we don't have any electric field between the shield and anode and reduce the avoid effect of this electric field this one is a little bit sick that's because we need to apply the counting gas with the positive pressure that's because the distance between the castle the grid is 2.5 cm 2.5 cm the normal gas pressure is not enough to stop the alpha particle what we want to measure so we put the pressurized gas up to 10 atom and then stop the proton so here is the vacuum line that's because we have to use the pressurized gas so we have to shield the vessel so before shield the vessel we need to pump out and make a vacuum and to avoid the contamination and then close the valve and introduce the gas from outside that is the structure so this is the sample changer mechanism here is the gear and we can set the three samples at the same time so the one is for example nickel 58, the other is natural nickel and one is the backing itself and then repeatedly change and do the experiment measurement but sometimes the position hold the situation we put the small amount of magnesium here and check the position to the rotating where we are and also this magnesium is alpha emitter 5.48 5.5 MED alpha is used for calibration so this is the cross section so this is the this part that is corresponded here and we have some of this difficult structure that is a bit problem that is because we cannot measure the exact 90 degree alpha part that is because of this structure but anyway this is the sample changer so our detector parameter distance between the electrodes electrode means the cathode and grid so effectively distance to stop 75mm and diameter of electrode is 75mm and distance between grid and anode is 5mm we can calculate the shielding efficiency that is described by using this equation as a function of the wire spacing and the wire radius and distance between anode and grid so typically we can fill the glass with 10 atom that is the reason is simply that Japanese regulation we need to have some of the inspection if we want to exceed 10 atom so that 10 atom is the limit that is because of the regulation and then later I can show you the drift velocity and then we applied high voltage of 6kV and 9kV and anode we have some of the drift velocity and then that is the power shaping determine so here is the feeling talking about the feeling gas so feeling gas as you may know we use the noble gas typically with a few percent of molecular gas that drastically improve the electron drift velocity so normally we use the argon krypton avenid xenon you can see there are many curves I am sorry this one is too small to take a look but normally we use CH4 that is a metan or CO2 this case also CH4 and CO2 so what is interesting is here the horizontal axis correspond to the electric field strength and vertical axis correspond to the velocity of the electron so once we increase the electric field so of course the direct velocity is also increased but some of the point the velocity is saturated so the point what we want to use that is because we don't need to apply much more electric field that is because there is a high voltage limitation also there is a chance to discharge there are many problems we are going to have so we can use this as a saturated point so that one is for example so here is 0.2 a few percent of the metan or a few percent of CO2 the case 0.2 or 0.3 that is a typical number of the required electric field so if we use the one atom gas and also the drift distance 5 cm our case is 2.5 but let's assume 5 cm so that's a one atom 5 cm multiplied so we need 1 kV high voltage and then this one provides 3 cm per microsecond the drift, electron drift velocity that's a typical number so that's a few cm it's an ionization chamber you apply the kV and then the correction time is microsecond ok so the gas pressure how to determine the gas pressure that's not so difficult just adjust the thickness which you need thickness means the function of the half vertical energy so let's assume for example the energy of the half vertical is 10 MeB so we choose the krypton gas that's because of the background and then that's how much length we need is 69.85 mm that's more than 25 mm which is the spacing of our chamber so what should we do is just increase the gas pressure to fit the range of 2.8 atom for example we need so the important thing is this the nickel irradiated by neutron and then produced alpha but also the proton also and the proton under this condition the proton can stop 2.5 MeB proton could be stopped under this pressure so naturally we can discriminate the high energy proton even that's because of detector thickness so we can measure the 10 MeB up to 10 MeB alpha particle but we cannot measure more than 2.5 MeB so that we can reduce the effect from proton by using the gas condition but of course we can apply much more high pressure so that case let's say 10 atom is the 10 MeB alpha particle or more but the proton energy also increased that's 5.5 for example so under this condition there's 2.8 atom so we have the clean area from the 2.5 to 10 MeB for alpha particle but that area region is reduced so the important thing is the minimum gas pressure should be chosen for measurement ok so here is the gas filling system as I told you before here is the graded ionization chamber so before filling the gas we make the vacuum to remove the impurities of gas or air inside the graded ionization chamber it takes dates actually and then let's close the valve and fill the gas from the gas bottle and one of the important thing is the contamination of gas so we use the oxygen trap to remove the oxygen that is the electronegative gas so that easily attach the electron and then reduce the power size signal and here is the electronics that's really old actually now normally connected to the pre-amplifier and then it's a spectroscopy amplifier and the ADAC for power site analyze these three parameters that's anode and cathode and then it's because of the neutron experiment we have so many background and also the noise so to reduce the noise count we need some of the conditions between the cathode and anode and then it's a gate the signal that's not special so before taking the data we need to check the detector condition by taking the saturation that's because we need to make sure all electrons should be corrected so we need to check the power side or instead a machine alpha particle and then changing the electric field and then check the saturation and determine the applied voltage it slightly depends on the gas pressure so every time we need to check the kind of saturation and also that's a we have to correct think about geometrical inertia that's because we installed the sample change mechanism but the mechanism provide some of the difficulty that's because of the angled the alpha particle cannot measure that because of this structure so we do the Monte Carlo calculation and then here is the horizontal axis the emission angle and this is the probability so that the angled particle cannot measure that's because of this structure and this is the experimental data radar I will explain how to take a look at this one but actually this one is confirmed by experimentally by using the sixth regime and thermal T-alpha reaction for counting gas so there are several choices for counting gas the one is argon or krypton and even for xenon several here is one of the examples so this is horizontal axis corresponding to the power height and then vertical corresponding number of counts so the power height is equal to the energy so once we use the argon plus 5% CO2 gas as a counting gas so the dot corresponds to the sample that's the sample at this moment is a nickel sample so the nickel alpha we can observe there are the significant the background because of argon and alpha reaction and also the oxygen and alpha reaction so that situation is not preferable so we change the gas to the krypton so the krypton case the reaction channel is closed that's because of the Q value and also that's only that we have the oxygen and alpha reaction peak in here if you don't want the oxygen and alpha peak in some of the case some of the case means we have to measure the low energy alpha particle that case we don't want huge oxygen peak so we can use the CH4 to remove the oxygen we don't have any peak component here but we have huge component of recoil proton in here it's a trade-off we also take care about the background from the chamber itself and electrodes as I show you the structure the chamber is totally shielded by electrodes and electrodes made from heavy metal which has the high coolant barrier to prevent the alpha particle emission that is a special for neutron cross-section measurement so here is the two-dimensional plot of the anode output and castle output as I told you that's anode output correspond to the energy and once we fix the anode output distribution correspond to the emission angle so this one is with target and without target and here is the alpha area so you can see almost nothing here that's a very nice condition for example and then let's we use the 300 microgram Pascal centimeter as a nickel for the measurement so that one needs enough thin to resolve the several the component you can see this straight line so this point is correspond to 0 degree and this point is 90 degree so how to analyze the data by using the 2D sorting so that one is correspond to the 0 degree the cosine is 1.0 and cosine is 0.8 and 0.6 and 0.4 and 0.2 and 0 and make a slice and then it's 3 of 1D spectrum we have to normalize this energy this energy spectrum by using the target thickness and the number of neutron so the target thickness provides the number of target atom and then this one is the later I will explain that's the number of proton, nickel proton convert to the neutron flux and then normalize so after normalization we have the double differential cross section in rubber to system so we change and convert the rubber to system to CM system and then it's integration as a energy according to the energy and then it's the angular differential cross section the angular differential cross section integrated concerning the angular angular angles by using the Roussian and then there's the production cross section finally we have so how to measure the neutron flux is very simple so just put on this is a telescope which is here is the poly etching film and here is the surface barrier detector that's a very simple structure we have to make a vacuum inside so once irradiates the system for neutron so we have this kind of spectrum so after that we remove the poly etching and then take the background so we have some of the differences here it's correspond to the proton event from the poly etching so you know that's a HNP that's a cross section in the standard we have data so using the cross section we estimate the neutron flux from this structure so you can see there's a several peak structure that's because of the interaction inside the silicon detector so silicon detector also that's have an alpha cross section and then this one is an alpha 0 an alpha 1 or something like that but in this energy it's not significant so we can subtract the effect by using the background measurement but if you don't want to subtract the system so in that case we may put some of the transmission detector and the required consistency so totally disappear the event so this is the example of the alpha particle W dihilation cross section so horizontal axis correspond to the energy MEV and vertical axis the cross section the neutron energy is 5 MEV and this is for 32 degree and this is the background angle 148 degree so this spectrum you can see only the difference is the sample thickness this one is 0.3 milligram per square centimeter and this one is correspond to the 3 millimeter it's a 10 times thick so you can see in the same sample some of the structure that's because the residual nuclei of energy reaction we have 55 iron that's the grand state and the first excited state is the 400KB difference to observe such difference we need to use same sample 6 sample 3 milligram per square centimeter the residuals in the sample reach to the more than one MEV so we cannot observe this structure by using 6 sample ok here is the one of the example of the double differential cross section for different energy this is the 5.2 MEV and this is the 6.2 MEV and the angle is the 32 degree and 63 degree so with increasing the energy we can observe much higher state component in here still keep alpha 0 and 1, 2, 3 and the line is just theoretical calculation for the statistical decay model and the fairly agreement some of the difference in here in the animation so by integrating the energy so we can obtain the angle distribution for example for each component this alpha 0 and alpha 1 and more than alpha 2 so that's some of the difference according to the component here is the angle and this is the cross section by integrating this point and then we have the cross section for the alpha 0 and alpha 1 and alpha 2 and more and the line is again the theoretical calculation and it's really difficult to take a look but this one is a triangle and obtained by the Obnitz group and it's a very good agreement between our data for alpha 1 and alpha 2 and more but alpha 0 is some of the difference we observe one is the final slide I think that's a total that's an exciting function of 58 nickel and also that's a natural nickel that's a X alpha reaction cross section so we have several data and still scattered out but maybe the difference is within the factor so let me summarize the first talk about the neutral induced alpha produced W-harassian cross section measurement so the first talk about the neutral production and then let's talk about the EDU estimation and the detector itself that's all I have for today so thank you